The Southern Sky Guide, 3rd Edition

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The Southern Sky Guide Thi r d Ed i t i o n

Both novice and advanced skywatchers will value this comprehensive and easy-to-use guide to the brilliant and ever-changing sights of the southern sky by night. Readers are introduced to the many and varied objects in the sky and their movements and changing appearances, as well as the ancient myths and legends entwined around the ­groupings of stars. Featured in this book are two groups of sky charts, designed so that readers can move easily between them.The 24 Skyviews show the appearance of the whole night sky every two weeks (or at each hour of sidereal time). The 20 Sky Charts show particular areas of the night sky in detail and are accompanied by explanatory text. This new edition features: • digitally re-drawn Skyviews, Sky Charts and map of the surface of the Moon • a table of planet positions up to 2017. David Ellyard is an award-winning freelance science writer and broadcaster with a life-long passion for astronomy. Wil Tirion is a Dutch celestial cartographer and is widely regarded as the leading exponent of his art in the world.

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The

Southern Sky Guide

T hir d E dit io n David Ellyard and Wil Tirion

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CAMBRIDGE UNIVERSITY PRESS

Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521714051 © David

Ellyard and

Wil Tirion 2008

This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published in print format 2008

ISBN-13

978-0-511-47858-1

eBook (EBL)

ISBN-13

978-0-521-71405-1

paperback

Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.

contents the panorama of the night sky

Starting with the stars Star stories The stars by name Brighter and fainter stars How far away are the stars? Stars of many colours Sizes and distances in the sky More than one at a time Stars that change The heavens in motion Mapping the sky The line around the middle The grid of the sky: (a) declination The grid of the sky: (b) right ascension Sun and Moon The ecliptic and the zodiac Sky change throughout the year The moving Moon Eclipses The face of the Moon The planets The movements of the outer planets The movements of the inner planets Which planet? The waltz of the planets Satellites, comets, meteors, minor planets A variety of sights Stars get together The Milky Way Nebulae, dark and bright Nebulae beyond

1 the skyviews

1 1 6 6 6 7 8 8 8 9 9 9 12 12 12 12 13 13 14 14 14 14 16 16 16 17 17 17 18 18 18

Using the Skyviews The Skyviews 1–24

21 21 23

the night sky in detail

47

Appendixes

89

INDEX

97

Using the Sky Charts The Sky Charts 1–20

A: Using binoculars and telescopes B: Planet positions 

list of tables

Table 1. The 88 constellations Table 2. The 25 brightest stars Table 3. Main meteor showers Table 4. Choosing the right Skyview Table 5. Planet positions 2008–2017

47 48

89 90

2–3 7 17 21 91–95

list of illustrations

Constellations 4–5 Whole-sky map 10–11 The main features of the surface of the Moon 15 The Skyviews 23–46 The Sky Charts 48–87

v

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THE PANORAMA OF THE NIGHT SKY

When the night sky is dark and clear, it presents a daz­zling spec­ta­cle. Myriads of stars, glowing patches of gas, a planet or two, the Moon in its phases, perhaps a meteor shower, an eclipse of the Moon or even a comet, all such sights are there for the taking by anyone who cares to look up. Even when dimmed by city lights and smog, the night sky is worth a long look. The pano­rama is con­stantly chang­ing, with the view never quite the same, even on suc­ces­sive nights. There is always some­thing of inter­est, some sight to appre­ ciate, whether you are viewing with binoc­u­lars, a small tele­ scope, or just with your unaided eyes. Astronomy, the science of the stars, is perhaps the most ancient form of method­i­cal human knowl­edge. To track the paths of the celes­tial lights today is to retrace the steps of the first observ­ers many thou­sands of years ago.

Starting with the stars Most of the things we see in the night sky are stars, vast balls of glowing gas similar to our Sun but so far away from us that they are reduced to mere points of light, scat­tered mostly at random across the heavens.The unaided human eye can detect about 6000 stars under dark, clear con­di­tions, but less than half of those are visible at any one time. For thou­sands of years, sky­watch­ers in various cul­tures have been group­ing the stars together into unchang­ing pat­terns know as constellations or ast­er­isms (both expres­sions come from Greek or Latin words for ‘star’). These change their posi­ tions and orien­ta­tions in the sky through­out the night and the year, but their shapes do not vary notice­ably.You can always pick them out and together they (and the brighter stars in them) form a grid of famil­iar ref­er­ence points across the night sky. Nowadays, 88 con­stel­la­tions are offi­cially rec­og­nised. Many other con­stel­la­tions have been devised over the cen­tu­ries but have now fallen into disuse. All con­stel­la­tions have names, and the older and more spec­tac­ul­ar ones have myths and legends asso­ciated with them in many cul­tures. The best known of these stories are drawn from the mythol­ogy of ancient Greece and Rome, tales of gods, mon­sters, heroes and great deeds.

Star stories For example, the story of Andromeda, the maiden chained to the rock, is recounted in no less than six con­stel­la­tions. Among the stars we find Andromeda herself, the monster Cetus sent to devour her, her rescuer Perseus, her parents

Cepheus and Cassiopeia, and the won­der­ful winged horse Pegasus (even though it was only periph­eral to the Andromeda story). The leg­en­dary quest of the Argonauts for the Golden Fleece has many memo­ri­als in the sky. In addi­tion to their ship, the mighty Argo itself, now broken into its Keel (Carina), Sail (Vela), Poop (Puppis) and Compass (Pyxis), we also find the won­der­ful ram that pro­vided the fleece (Aries), some of the Argonauts (Gemini the Twins, Hercules and Orpheus the Musician, through his harp Lyra), and even the centaur Chiron (Centuarus) who tutored the expe­di­tion leader Jason. There are still more, if you take the figure of Ophiuchus, the man holding a serpent, to be Aescalepius, the ship’s doctor on the Argo, or the north­ern figure of Draco to be the serpent that guarded the sacred grove where the Fleece hung, or Taurus to be one of the fire­breath­ing bulls with horns of brass that Jason had to tame. Strangely, Jason himself is not on show. There are some vivid scenes. Orion the Hunter, accom­pa­ nied by his two dogs (Canis Major and Canis Minor), is in trouble with a charg­ing bull (Taurus), and is unknow­ingly tram­pling on a hare (Lepus). Ophiuchus has his hands full with the serpent.The two cen­taurs are pre­oc­cu­pied; Centaurus is fight­ing a wolf (Lupus) and Sagittarius the Archer has an arrow aimed at the fear­some Scorpion. Leo recalls the Nemean Lion slain by the mighty Hercules as one of his 12 labours, and Cancer the Crab that bit his heel while he was bat­tling with the many headed Hydra (and was crushed as a result). In the sky, Hercules has his foot on the head of a Dragon. So the ­struggle goes on. The posi­tions of some of the star groups are sig­nif­i­cant. Crater the Cup, Corvus the Crow and Hydra the Water Snake lie close together because of the story they share (see text to Sky Chart 8). Orion, so the legend goes, met his end when stung by the Scorpion. As a result, they are on oppo­site sides of the sky, one rising while the other sets. Libra the Scales, lying between Virgo the Young Maiden and Scorpius, has links to both. As the Goddess of Justice, Virgo weighed the evi­dence on the scales near at hand. But in some old lists, Libra was not its own con­stel­la­tion but the greatly enlarged claws on the Scorpion coming close behind. In one region of the sky, all the star groups have to do with water. Most likely, this served as a cal­en­dar, indi­cat­ing when the rains would come. Not all the con­stel­la­tions are so excit­ing. Many are quite dull, espe­cially those more recently named in south­ern skies which could not be seen from the Middle East in ancient times. Among these we find many sci­en­tific instru­ments! Constellations vary greatly in size and many are ­surprisingly

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large, though this is perhaps not so surprising when we realise only 88 cover the whole sky. The largest of all (though not otherwise spectacular) is Hydra at more than 1300 square degrees, six or seven times bigger than your hand at arm’s

length. Virgo is not far behind, and half a dozen are 1000 square degrees or more. At the other end of the scale, the Southern Cross is less than 70 square degrees in size, and half a dozen thumbs will hide it.

Table 1. The 88 constellations Proper name

Meaning

Size (square degrees) 25 brightest stars

Andromeda The Chained Maiden   722 Antlia The Air Pump   239 Apus The Bird of Paradise   206 Aquarius The Water-Carrier   980 Aquila The Eagle   652 Altair Ara The Altar   237 Aries The Ram   441 Auriga The Charioteer   657 Capella Bootes The Herdsman (or   907 Arcturus    Waggoner or Ploughman) Caelum The Engraving Tool   125 Camelopardalis The Giraffe   757 Cancer The Crab   506 Canes Venatici The Hunting Dogs   465 Canis Major The Big Dog   380 Sirius, Adhara Canis Minor The Little Dog   183 Procyon Carpricornus The Sea-Goat   414 Carina The Keel (of Argo)   494 Canopus Cassiopeia (mother of Andromeda)   598 Centaurus The Centaur 1060 Rigil Kentaurus (Alpha Centauri), Hadar (Beta Centauri) Cepheus (father of Andromeda)   588 Cetus The Sea Monster (or Whale) 1231 Chamaeleon The Chamaeleon   132 Circinius The Pair of Compasses    93 Columba The Dove   270 Coma Berenices Berenice’s Hair   386 Corona Australis The Southern Crown   128 Corona Borealis The Northern Crown   179 Corvus The Crow   184 Crater The Cup   282 Crux The (Southern) Cross    68 Acrux, Mimosa, Gacrux Cygnus The Swan   804 Deneb Delphinus The Dolphin   189 Dorado The Gold-Fish   179 Draco The Dragon 1083 Equuleus The Colt    72 Eridanus The River 1138 Achernar Fornax The Furnace   398 Gemini The Twins   514 Pollux, Castor Grus The Crane   366 Hercules 1225 Horologium The Clock   249 Hydra The Female Water-Snake 1303 Hydrus The Male Water-Snake   243

Month when Go to highest at 8 p.m. Chart November April July October August July December February June

13 8 3 12 19 3 13 15 17

January

1

March June February February September March

15 17 7 7, 15 11 2

May

3, 9

November April May February May July June May April May September September February

5 2 3 6 17 4, 11 18 9 8 3 19 19 1

September December December February October July December April December

19, 20 1, 6 1, 5 15 4 18 1 8, 9 1

2

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A full list of the 88 con­stel­la­tions, the mean­ings of their names, their bright­est stars, their sizes, their posi­tions in the sky and on the maps in this book is given in Table 1. Pages 4–5 provide a first look at the better-known and more spec­tac­u­lar

star groups in the form of dia­grams marking their shapes and more notable stars. More details on these (and more on the stories asso­ciated with them) can be found along­side the Sky Charts later in this book (pages 48–87).

Table 1. (cont.) Proper name

Meaning

Size (square degrees) 25 brightest stars

Indus Lacerta Leo Leo Minor Lepus Libra Lupus Lynx Lyra (Mons) Mensa Microscopium Monoceros Musca Norma (et Regula) Octans Ophiuchus Orion Pavo Pegasus Perseus Phoenix Pictor Pisces Piscis Austrinus Puppis Pyxis Reticulum Sagitta Sagittarius Scorpius Sculptor Scutum Serpens Sextans Taurus Telescopium Triangulum Triangulum Australe Tucana Ursa Major Ursa Minor Vela Virgo Volans Vulpecula

The Indian   294 The Lizard   201 The Lion   947 Regulus The Lesser Lion   232 The Hare   290 The Scales   538 The Wolf   334 The Lynx   545 The Harp   286 Vega The Table Mountain   153 The Microscope   210 The Unicorn   482 The Fly   138 The Level (and Square)   165 The Octant   291 The Man with the Serpent   948 The Hunter   594 Rigel, Betelgeuse The Peacock   378 The Winged Horse 1121 (rescuer of Andromeda)   615 The Phoenix   469 The Painter’s Easel   247 The Fish   889 The Southern Fish   245 Fomalhaut The Poop (of Argo)   673 The Compass (of Argo)   221 The Reticule   114 The Arrow    80 The Archer   867 The Scorpion   497 Antares, Shaula The Sculptor’s Chisel   475 The Shield   109 The Serpent   637 The Sextant   314 The Bull   797 Aldebaran The Telescope   252 The Triangle   132 The Southern Triangle   110 The Toucan   295 The Great Bear 1280 The Little Bear   256 The Sail (of Argo)   500 The Young Maiden 1294 Spica The Flying Fish   141 The Fox   268

Month when Go to highest at 8 p.m. Chart September September April April January June June March August February September February May July All months July January October October December November February November October February March December August August July November July July April January August December July November April

4 20 16 16 6 9, 10 3 15 19 1, 2 4 7 3 3 3, 4 10 6 4 20 14 1 1 4, 13 12 2, 7 2 1 19 11 10 5 12 10, 11 8 6, 14 4 13 3 1, 4 16

March May February September

2 9 2 19

3

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LIBRA

22h

AQUARIUS

HYDRA

12 h

h

15

0h

–30o

0o

PISCES

S

SCORPIUS

LUPUS CENTAURUS

PEGASUS

S Mimosa

LUPUS, CENTAURUS, CRUX

Hadar

Best visible: April – August

Rigil Kentaurus

+30o

VELA

CRUX

PEGASUS

–6

Acrux

0o

Best visible: October – November

CARINA

12h

0h

3h

VELA, CARINA, PUPPIS

9h

Best visible: January – May

S

+60o

ANDROMEDA

PEGASUS

VELA

CANIS MAJOR

CENTAURUS

PERSEUS

Adhara

PUPPIS

0o –3

ANDROMEDA

Algol

CRUX h

6

Acrux

+30o

ARIES

S

PISCES

CARINA

PERSEUS, ANDROMEDA Canopus

0o

–6

Best visible: December

TAURUS

ANDROMEDA

TAURUS, ARIES

Best visible: December – January

5h

+30o

VIRGO

2h

–10o

PERSEUS

GEMINI

CRATER

S Pleiades

CORVUS

HYDRA

ARIES HYDRA

TAURUS ECL

Aldebaran

IPTI

C

PISCES

–30o

HYDRA

CORVUS, CRATER

+10o

Best visible: March – June

12h Betelgeuse

S

ORION

TAURUS

CANIS MINOR, ORION, CANIS MAJOR, LEPUS

CETUS

Best visible: January – March

CANCER, GEMINI Best visible: January – March

ARIES

S

1h

3h

CANIS MINOR Betelgeuse +10o

Castor Pollux

GEMINI ECLIPT

EC

LIP

TIC

0o

ORION

TAURUS

LEO

CANCER

PISCES

+30o

Procyon

S

Mira

AQUARIUS

Rigel

S

IC Sirius

CETUS

LEPUS

CANIS MAJOR –30o

Procyon

ORION

HYDRA

9h

CANIS MINOR

7h

+10o

CETUS

Best visible: November – January

Adhara

–30o PUPPIS

6h

5h

4

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10h

12 h

S

h

12

BOOTES

CANCER

+30o

LEO

+50o

o

+20

16 h h

14

Arcturus

14h

VIRGO

S

LEO

S Regulus

EC

LIP

BOOTES

TIC

Arcturus

LEO

VIRGO

VIRGO

0o

Best visible: March – May

+20o

Spica

0o

Best visible: April – June

–2

HYDRA

BOOTES

LIBRA

+10

Best visible: May – July

VIRGO

AQUARIUS

o

CAPRICORNUS, SAGITTARIUS

–10o

Best visible: July – October

SERPENS CAUDA CAPRICORNUS EC

OPHIUCHUS

S

IPT

PT

IC

SERPENS CAPUT –30o

ECL

LI

–40o

18 h

S

IC

SAGITTARIUS

21 h

OPHIUCHUS, SERPENS SAGITTARIUS

Best visible: June – August

16 h

SCORPIUS

SCORPIUS, LIBRA

18 h

HYDRA ( + Corvus, Crater)

Best visible: May – August

12h

LEO

SCORPIUS

9h

Regulus

CANCER

Best visible: March – May –10o

OPHIUCHUS

VIRGO

LIBRA IC ECLIPT

VIRGO

Antares

E

I CL

PT

0o

IC

CRATER

Spica

SCORPIUS

HYDRA

CORVUS

S

S

15 h

h

18

LUPUS

–40o

–30o

CENTAURUS

SAGITTARIUS

23h

ANDROMEDA

21h

0o

PISCIS AUSTRINUS, GRUS

AQUARIUS

23h

2h

PISCES

Best visible: August – December

+30o

ARIES

PEGASUS

–30o

Fomalhaut

PISCIS AUSTRINUS

S

AQUARIUS

EC

LIP

TIC

CAPRICORNUS

Fomalhaut

Best visible: September – November

GRUS

S 0o

PISCIS AUSTRINUS

AQUARIUS

S

PISCES

–50o

PISCES

–30o CETUS

Best visible: October – December

23h

21 h

AQUARIUS

5

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The stars by name The night sky is a friendly place. You can greet many of the stars by name. At least 100 of the brighter stars have proper names, mostly Greek, Latin or (par­tic­ul­arly) Arabic in origin. For example, Fomalhaut means ‘the mouth of the fish’, and Rigel means ‘the foot’ (of Orion). Antares means ‘the rival of Ares’, because its red colour is similar to that of the planet Ares (now called Mars). Regulus in Leo the Lion means ‘little king’ and Deneb is ‘the tail’ of Cygnus the Swan. It is fitting that Sirius, the bright­est of the night-sky stars, has a name meaning ‘the spark­ling one’. Many of these names have become very garbled over the cen­tu­ries and their origins are hard to find. Astronomers do not use these names much, espe­cially as only the brighter stars have them. Instead they follow a prac­tice popu­lar­ised in the early seven­teenth century by the German astron­o­mer Johann Bayer, though the system dates back to Ptolemy. They attach the letters of the Greek alpha­bet (alpha, beta, gamma, delta, epsilon, and so on) to the stars in a con­stel­ la­tion in general order of bright­ness. After the letter comes the name of the con­stel­la­tion in the pos­ses­sive (or gen­i­tive) form. When the Greek letters run out (which does not take long in most con­stel­la­tions) ordi­nary Roman letters are used. For example, Antares (which marks the heart in the strik­ ing con­stel­la­tion of Scorpius the Scorpion) is offi­cially Alpha Scorpii. Rigel, Betelgeuse and Bellatrix in Orion the Hunter are respec­tively Alpha, Beta and Gamma Orionis. Regulus is Alpha Leonis and so on. The bright­est star in a con­stel­la­tion is usually called alpha, but this is not always the case. For example, Pollux in Gemini the Twins is brighter than his brother Castor but is ranked as Beta Geminorum. The ­discrepancy is some­times due to stars varying in bright­ ness over the years, as with Betelgeuse in Orion, which is now notice­ably fainter than Rigel. The two ‘pointers’ that indi­cate the way to the Southern Cross are known both as Rigil Kentaurus (‘the foot of the Centaur’) and Hadar (for ‘ground’) and as Alpha and Beta Centauri, being the bright­est stars in the con­stel­la­tion of Centaurus the Centaur. The Southern Cross itself is known as Crux Australis. Its five main stars in order clock­wise, begin­ ning at the bottom, are Alpha Crucis (also called Acrux), Beta Crucis (Mimosa), Gamma Crucis (at the top), Delta Crucis and Epsilon Crucis. The Greek alphabet            

           

alpha be¯ta gamma delta epsı¯lon ze¯ta e¯ta the¯ta io¯ta kappa lambda mu¯

           

            

nu¯ xı¯ omicron pı¯ rho¯ sigma tau upsı¯lon phı¯ chı¯ psı¯ o¯mega

Another naming system was begun by English Astronomer Royal John Flamsteed in 1725. This numbers the stars in a con­stel­la­tion by posi­tion, usually by increas­ing right ascen­ sion (see page 12), for example, 61 Cygni. Brighter stars will have several names. Betelgeuse is 58 Orionis as well as Alpha Orionis. There are other naming systems for var­i­able stars and for double stars, usually based on various cat­a­logues.

Brighter and fainter stars Not all the stars look the same. They differ, not only in their posi­tions in the sky, but also in their colours and bright­nesses. The bright­ness of a star is indi­cated by its mag­ni­tude, making use of a system going back nearly 2000 years to the Greek astron­om ­ er Ptolemy. He divided the bright­nesses of the naked-eye stars into six levels, with the bright­est stars being of the first mag­ni­tude. Those stars are roughly two and a half times brighter than the more numer­ous second mag­ni­tude stars, which are in turn two and a half times brighter than the even more plen­ti­ful third mag­ni­tude stars. This means that a first mag­ni­tude star is six times brighter than a third mag­ni­ tude star, and 100 times brighter than a sixth mag­ni­tude star, the faint­est visible without aid. Nowadays this system had been extended. Magnitudes can be sub­di­vided, so that 2.3 is just fainter than 2.2, and just brighter than 2.4. First mag­ni­tude stars are those brighter than 1.5 (there are 21 of these), second mag­ni­tude objects are brighter than 2.5, and so on. Originally, the bright­ness of stars was judged by the expe­ri­enced eye; modern instru­ments assess bright­ness to one hun­dredth of a mag­ni­tude. Very bright objects have neg­a­tive mag­ni­tudes, such as the Sun (minus 27), the Moon (minus 12), some planets (for example, Venus can reach minus 4) and even some of the bright­est stars (for example, Sirius is now offi­cially listed as mag­ni­tude minus 1.5). The system works for fainter stars as well, with the faint­est stars detect­able with the largest tele­ scopes being of mag­ni­tude 27. (That makes them more than 10 billion times fainter than Alpha Centauri, the brighter of the two point­ers to the Southern Cross!)

How far away are the stars? To be precise, what we have dis­cussed so far is a star’s appar­ ent mag­ni­tude, that is, how bright it seems to be from Earth. That depends not only on how bright a star actu­ally is but also on how far away it is. For example, the two Pointers (Alpha and Beta Centauri) look to be about equal in bright­ness. But Beta is in fact 10,000 times brighter than Alpha and 100 times further away. The common measure of dis­tance in deep space is the light year. This is the dis­tance travelled by a ray of light (cov­ er­ing 300,000 km every second) in a year, and is equal to roughly 10 tril­lion (10 million million) kilo­me­tres. The nearest bright star to us (other than the Sun) is Alpha Centauri, the brighter of the two Pointers to the Southern Cross. This is a little over 4 light years away. Sirius is 9 light years distant, Canopus 74 light years, Spica 220 light years,

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Table 2. The 25 brightest stars Name

Constellation

Apparent mag.

Distance (l.y.)

Absolute mag.

Sirius Canopus Rigil Kentaurus Arcturus Vega Capella Rigel Procyon Achernar Betelgeuse Hadar Acrux Altair Aldebaran Antares Spica Pollux Fomalhaut Becrux (Mimosa) Deneb Regulus Adhara Castor Gacrux Shaula

Canis Major Carina Centaurus Bootes Lyra Auriga Orion Canis Minor Eridanus Orion Centaurus Crux Aquila Taurus Scorpius Virgo Gemini Piscis Austrinus Crux Cygnus Leo Canis Major Gemini Crux Scorpius

1.46 0.72 0.27 0.04 0.03 0.08 0.12 0.38 0.46 0.50 (var) 0.61 (var) 0.76 0.77 0.85 (var) 0.96 (var) 0.98 (var) 1.14 1.16 1.25 (var) 1.25 1.35 1.50 1.57 1.63 (var) 1.63 (var)

8.6 74. 4.3 34. 25. 41. 1400. 11.4 69. 1400. 320. 510. 16. 60. 520. 220. 40. 22. 460. 1500. 69. 570. 49. 120. 320.

1.4 2.5 4.1 0.2 0.6 0.4 8.1 2.6 1.3 7.2 4.4 4.6 2.3 0.3 5.2 3.2 0.7 2.0 4.7 7.2 0.3 4.8 0.5 1.2 3.5

Note: var  variable.

Antares 520 light years. About 25 stars lie within 12 light years of the Sun. The most distant first mag­ni­tude stars, such as Rigel in the con­stel­la­tion of Orion the Hunter or Deneb in Cygnus the Swan, are 1400 or 1500 light years away. To be seen so clearly at such a dis­tance they must be immensely bright, much brighter in reality than our Sun. The measure of intrin­sic bright­ness is abso­lute mag­ni­tude, which means how bright the star would appear to be if it was 33 light years away. Our Sun has an abso­lute mag­ni­tude of 4.8, while Rigel rates at 8.1. The dif­fer­ence of 13 mag­ni­tudes makes Rigel 60,000 times brighter than the Sun in reality. If Rigel were as close as Alpha Centauri, it would out­shine the Moon. The varying dis­tances to the stars have another impli­ca­tion. It means that the various star pat­terns as we see them from Earth are often purely a matter of chance and depend on our viewing point. From else­where in our stellar neigh­bour­hood, the Southern Cross may not look like a cross at all. Nor are the pat­terns eter­nally endur­ing. The seem­ingly ‘fixed’ stars are actu­ally hur­ry­ing through space at many kilo­me­tres per second. Even their great dis­tances from us will not hide that move­ment if we are willing to wait a few thou­sand years.

Stars of many colours Across the sky, we find stars of many colours. Green and purple stars may be rare but many stars have a red, orange or yellow tinge, or a hint or more of blue. Nowadays, we under­ stand that colour indi­cates how hot the surface of the star is. Stars cooler than our Sun are redder in colour (for example, Aldebaran in Taurus the Bull, or Gamma Crucis), and stars hotter than our Sun are bluer in colour (for example, Sirius or Beta Centauri). We also now know the link between a star’s colour and its intrin­sic bright­ness. For at least 90 per cent of stars, the brighter they are, the hotter (and there­fore bluer) they are. Such stars are also bigger and heavier than the dimmer, cooler, redder stars. They also have shorter lives. Our Sun has been shining for over 5 billion years and has some billions of years of life left yet. In contrast, very large, hot, blue stars exhaust their fuel in only a few million years. Most of the stars redder than the Sun (and there­fore smaller than it) are too dim to be seen with the unaided eye. There are excep­tions. A class of stars known as giants are both brighter and redder (or at least yel­lower) than our Sun. This is even truer for the super­giants. Both Betelgeuse and

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Antares are cool and red (at 3000 degrees their surface tem­ per­a­tures are half that of the Sun) but they are vast in size and bright­ness, 10,000 times or more the bright­ness of the Sun and perhaps 500 times its diam­et­er. Placed where the Sun is they would engulf the inner planets, includ­ing Mars. These behe­moths are stars in old age. Another group of stars, the white dwarfs, are both hot and dim.They are also small and rep­re­sent the remains of once much brighter and bigger stars. Their inner fires have gone out.

Sizes and distances in the sky It is useful early on to find a simple way to indi­cate the appar­ ent dis­tances between stars in the sky and the sizes of the con­stel­la­tions.The usual measure is in degrees with 90 degrees from the horizon to the zenith (the highest point in the sky, directly over­head) and 90 degrees between the four main points in the compass (say from north to east). Your hands are a good rough guide to dis­tances. The hand spread out at arm’s length meas­ures about 20 degrees from the tip of the thumb to the tip of the little finger. Across the clenched fist (includ­ing the thumb) totals about 10 degrees at arm’s length. A fist plus a span makes up 30 degrees, the size of many a large con­stel­la­tion, such as Leo or Orion or Scorpius. For smaller sep­ar­a­tions, use the thumb (about 2 degrees) or the little finger (about 1 degree), again at arm’s length. It is easy to over­es­ti­mate the sizes of objects in the night sky. The Moon, for example, is only half a degree across, and is easily covered by the little finger at arm’s length. Its appar­ ently larger size near the horizon is an illu­sion, as use of the little finger will quickly show. For small dis­tances, we break down each degree into 60  minutes (of arc) and each minute into 60 seconds. The Moon is there­fore about 30 minutes or 1800 seconds of arc across. We need these small meas­ures to describe, for example, the sep­ar­a­tions of double stars (page 8), which are usually meas­ured in seconds of arc, or the sizes of nebulae (pages 18–19), which usually amount to some tens of minutes of arc. Minutes of arc are denoted by the symbol , seconds by .

More than one at a time Most stars have some addi­tional point of inter­est. For instance many are multi­ple stars, two or more stars revolv­ing about a common centre. Of the 25 stars within 12 light years of our Sun, 17 belong to double or even triple star systems. Our Sun, having no com­pan­ion, is in the minor­ity. Alpha Centauri, the nearest star to the Sun, is a triple. Two of its com­po­nent stars are close and similar, being both Sun-like. The third, a dim red star called Proxima Centauri, is suf­fi­ciently far away from the other two to be notice­ably closer to us. The most spec­tac­u­lar multi­ple stars are those in which the com­­po­ nent stars are about equal in bright­ness but dif­fer­ent in colour. To the naked eye, nearly all these multi­ples appear to be single stars, but in many cases binoc­u­lars or a small tele­scope can dis­tin­guish the sep­ar­ate stars. The closer together the stars are the larger the tele­scope needed to sep­ar­ate them.

Under ideal con­di­tions, a pair of good binoc­ul­ars with 50 mm lenses will be able to sep­ar­ate a pair of sixth mag­ni­ tude stars only two and a half seconds of arc apart (a second of arc is about 2000th of the appar­ent angular diam­e­ter of the Moon). A tele­scope of 120 mm aper­ture will sep­ar­ate a pair only 1 arc second apart. The stars are harder to split if they are unequal in bright­ness, or if they are much fainter or brighter than the sixth mag­ni­tude. There are some notable naked-eye doubles, such as Theta Tauri and Epsilon Lyrae. The latter is a good test of keen sight, while each com­po­nent is itself double, with a small tele­scope needed to resolve them. Various astron­o­mers have assem­bled cat­a­logues of multi­ ple stars. Three drawn on in this book are those of Dunlop (sig­nified by a Greek delta), Struve (Sigma) and Herschel (h). The Dunlop list con­tains many south­ern stars.

Stars that change Other stars provide fas­ci­na­tion by varying in bright­ness, by a little or a lot, reg­ul­arly or unpre­dict­ably. About 3 per cent of all naked-eye stars are var­i­ables. You can tell a var­i­able star from its name. The letters R to Z are put in front of the name of the con­stel­la­tion, and if more names are needed, the system uses the pre­fixes RR to RZ, SS to SZ and so on. For example, RR Lyrae is a var­i­able star (and a famous type of var­ia­ ble star at that). These var­i­able stars are of several types. About 20 per cent of var­ia­ ble stars are eclips­ing var­i­ ables. These are double stars so aligned that one of the pair passes first in front of and then behind the other. The way the bright­ness of the com­bined light of the two stars varies depends on their rel­a­tive bright­nesses. If one is very much brighter than the other, there will be one deep minimum in the ‘light curve’ (when the dim star hides the bright one) and  one shallow maximum (when the bright star is in front).   This is the case with the most famous such star, the ‘demon star’ Algol (Beta Persei). This varies in mag­ni­tude from 2.2 to 3.5 every three days. In the case of Beta Lyrae, the stars are more even in bright­ness and the light varies more grad­u­ally over the whole period. Far more common (more than 60 per cent of all var­i­ables) are single stars that pulsate in some way, mostly in and out. For such pul­sat­ing var­i­ables, the amount of change and the time taken cover a wide range and have a range of causes. For Mira-type stars (of which Omicron Ceti, the ‘won­der­ ful star’ is the proto­type), a typical range of mag­ni­tudes is 4 to 11 (that is, from a naked-eye object to one invis­ible even in binoc­u­lars), with the vari­a­tions taking any­thing from 80 to 1000 days. Mira-type stars are red giants or super­giants and make up one fifth of all var­i­ables. For Cepheids (of which Delta Cephei is the proto­type), bright­ness will swing by two mag­ni­tudes in between one and 135 days. Though quite rare (less than 1 per cent of all var­i­ ables) Cepheids are of par­tic­u­lar inter­est, since the time taken for the swing is directly related to the star’s abso­lute bright­ ness. This has let astron­om ­ ers use them as ‘stan­dard candles’ to plot dis­tances in the uni­verse. Cepheids are super­giant blue

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and white stars, which appear to inflate and deflate in size by about 10 per cent. RR Lyrae stars are similar to Cepheids, but the vari­a­tions take two days at most. Flare stars or novae sud­denly increase in bright­ness by a factor of a thou­sand or more, and then fade away once more into obscur­ity. Many other stars are irreg­ul­ar var­i­ables or semi­ reg­u­lar at best. Betelgeuse is an example. That makes their swings hard if not impos­sible to predict and there­fore more impor­tant to track. Amateur astron­o­mers can play a sig­nif­i­cant role here.

The heavens in motion The heavens do not stand still.Throughout the night, the posi­ tions of the stars change rel­a­tive to the horizon and the zenith, though not rel­a­tive to each other (that is, the con­stel­la­tions hold their shapes). Generally speak­ing, stars first appear some­ where along the eastern horizon and slowly move west­wards across the sky. They are highest in the sky when cross­ing the median, that is, the line north and south passing right over­ head (through the zenith). Some hours later, the stars in ques­ tion will set at some point on the western horizon. Even 10 minutes of observ­ing, using your hands to mark the posi­tion of a bright star rel­a­tive to some nearby object such as a tree or build­ing, will show that the stars are on the move. Since the heavens turn over roughly once a day, the stars shift by some 15 degrees every hour. That is about one and a half fist widths at arm’s length. This grand motion, like so many in the night sky, is only appar­ent, since it is actu­ally the Earth that is turning from west to east. For stars high in the south­ern sky, the turning of the earth shows as a steady clock­wise move­ment of the stars around a fixed point known as the south celes­tial pole (‘south pole’ for short). This point lies due south and at an angle above the horizon equal to the observer’s lat­i­tude. For an observer at 35 degrees south lat­i­tude, the pole lies 35 degrees above the south­ern horizon. For observ­ers further north, it is lower in the sky, for those further south, it is higher. The south­ern stars appear to circle the pole at the same 15 degrees per hour rate, amount­ing to a 90 degree or right angle shift every six hours. This means that, if a star such as Achernar lies due east of the pole at six in the evening, it would be above the pole at mid­night and due west of it at six in the morning. The north celes­tial pole, visible to people in Europe, North America and North Asia but below the horizon for us, is marked by a bright­ish star called Polaris (or the Pole Star), which marks the end of the tail of the con­stel­la­tion of the Little Bear (Ursa Minor). There is no southern ‘pole star’. The nearest star to the South Pole (Sigma Octantis) is quite faint (as its name would suggest), but the pole is quite easy to find using some of the nearby bright stars. A line extended through the long bar of the Southern Cross passes very close to the Pole, which lies some four cross-lengths (about 27 degrees) from Acrux. A line passing at right angles between the Pointers also finds the Pole. So the Pole lies where the two lines (through the Cross, between the

Pointers) intersect. A point on the horizon directly below the Pole marks due south. Skywatchers have no excuse for being lost if the south­ern stars are visible.

Mapping the sky To help us get to know the night sky better, skywatch­ers have been making maps and charts of the heavens for thou­sands of years, just as explor­ers and geog­ra­phers have done with the surface of the Earth we live on. The map on pages 10–11 is an example. It shows the whole sky in four pieces, with the brighter stars (down to mag­ni­tude 3) and the boun­dar­ies of the 88 con­stel­la­tions marked. The numbers in boxes refer to Sky Charts 1 to 20 in the third part of this book, which show the night sky in much greater detail. The Earth is a sphere (more or less) and the con­ti­nents and seas lie on its surface (more or less). The stars are very dif­fer­ ent. They lie at vastly varying dis­tances from us, and we can map them only by ima­gin­ing that they are attached to the inside of a vast ‘celestial sphere’ (size unknown) centred on the Earth (Indeed, until a few hundred years ago, most people thought that really was the case!). Trying to make maps on flat-plane paper of the inside of this celes­tial sphere meets the problem faced by car­tog­ra­phers on Earth. The job cannot be done without dis­tort­ing the picture, espe­cially away from the equator. Some maps show Greenland bigger than Australia, which is not the case. We have kept the dis­tor­tion down by drawing sep­ar­ate maps for the regions of sky around the north and south celes­tial poles. One aspect of the maps is puz­zling. With north at the bottom of the map, and south at the top, the right-hand end should mark the west. On a map of the Earth that would cer­ tainly be true. Instead, the right-hand end indi­cates the east. The dif­fer­ence arises from the fact a map of the surface of the Earth is drawn from the outside looking in. Sky maps are drawn from the inside of the celes­tial sphere looking out. This reverses some of the direc­tions.

The line around the middle If Map A were a map of the Earth, the line across the middle of the rec­tan­gu­lar chart (marked 0 degrees) would be the equator. On this map it marks the celes­tial equator, an imag­ i­nary line across the night sky, 90 degrees from each of the celes­tial poles (that is, running around the widest part of the celes­tial sphere). Where the celes­tial equator lies in the sky depends on where you are. For observ­ers on the Earth’s equator, it passes right over­head from east to west. If you were at the south (geo­graphic) pole, it would lie along the horizon, with the south celes­tial pole right overhead. Throughout the south­ern hemi­sphere, the celes­tial equator still cuts the horizon due east and west, but passes across the north­ern sky, missing the zenith by an amount equal to the observer’s lat­i­tude. Thus for an observer at 35 degrees south

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18h

17 h

h

CORONA AUSTRALIS

SCORPIUS

16 h

19

SOUTH POLAR REGION

20

h

h

21

15

SAGITTARIUS ARA

TELESCOPIUM

h

MICROSCOPIUM

NORMA

22 h

14

h

LUPUS

PAVO

CIRCINUS

TRIANGULUM AUSTRALE

Rigil Kentaurus

GRUS

23 h

Hadar

CENTAURUS

APUS

h 13

INDUS

Mimosa

OCTANS

0h

MUSCA

12h

Acrux –90o

CRUX

TUCANA CHAMAELEON

PHOENIX –80o

HYDRUS

VOLANS

–70o

HOROLOGIUM RETICULUM

VELA

DORADO

2

10 h

1h

11 h

MENSA

Achernar

h

CARINA –60o

ERIDANUS

Canopus

h

1h

PUPPIS

4h

h

8

5

2h

TUCANA

9

3

–50o

EQUATORIAL REGION 0h –60o

h

PICTOR

3h

4h

HYDRUS

h

COLUMBA

–40o

h

7

6h

5h

6h

RIGHT ASCENSION

7h

8h

9h

10h

11h

R

1 –60o

RETICULUM

Achernar

CARINA

DORADO

HOROLOGIUM

CENTAURUS

Canopus

PICTOR

PHOENIX

WEST

–50o

12h–60o

–50o

–50o

–40o

–40o

–30o

–30o

–20o

–20o

–10o

–10o

VELA ERIDANUS

–40o

CAELUM

PUPPIS

COLUMBA

ANTLIA SCULPTOR

–30o

FORNAX

LEPUS

CANIS MAJOR

–20o ERIDANUS

D E C L I N AT I O N

PYXIS

Adhara

Sirius

CRATER

CETUS

–10o Rigel

HYDRA

MONOCEROS

SEXTANS

Mira

VIRGO

C E L E S T I A L E Q U AT O R

0o

0o

Betelgeuse

+10o

0o

Procyon

ORION

CANIS MINOR

+10o

+10o

+20o

+20o

+30o

+30o

+40o

+40o

+50o

+50o

+60o

+60o

Regulus

ECL

PISCES

+20o

PEG

IPT

IC

LEO

Aldebaran

ARIES

GEMINI CANCER

TAURUS Pollux

+30o Castor

TRIANGULUM

LEO MINOR

+40o

WEST

ANDROMEDA

Algol

AURIGA PERSEUS Capella

+50o

LYNX

URSA MAJOR

CASSIOPEIA CAMELOPARDALIS

+60o

NOV

DECEMBER

JANUARY

FEBRUARY

MARCH

APRIL

MAY

Map A. Whole-sky map

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M

NORTH POLAR REGION

18h

19 h

17

h

16

LYRA

20 h

h

HERCULES

21

15

h

h

Deneb

CYGNUS

BOOTES

h

22

14 h

DRACO

h 23

13 h

LACERTA CANES VENATICI URSA MINOR

+90o

0h

12h

DRACO

CEPHEUS

Polaris

CASSIOPEIA

h 11

1h

+80o

URSA MAJOR

ANDROMEDA +70o

LMi

CAMELOPARDALIS

h

2h

10

+60o

LYNX

Algol +50o

8h

7h

RIGHT ASCENSION

12h–60o

12h

13h

–60o

14h

15h

16h

+40o

5h

6h

17h

18h

19h

Mimosa

CRUX

CIRCINUS

21h

22h

23h

0h–60o

TUCANA

INDUS

NORMA

–50o

20h PAVO

NTAURUS

–50o

EQUATORIAL REGION

h

4

AURIGA

ARA

PHOENIX

TELESCOPIUM

–50o

LUPUS

EAST

SION

PERSEUS

Capella

h

3

9

h

CENTAURUS GRUS

CORONA AUSTRALIS

–40o

–40o MICROSCOPIUM

SCORPIUS

PISCIS AUSTRINUS

SAGITTARIUS

–30o

–30o

–20o

CAPRICORNUS

CORVUS

ATER

–10o

EC

Spica

–10o

LI

SERPENS CAUDA

AQUARIUS

–10o

OPHIUCHUS

VIRGO

0o

0o

C E L E S T I A L E Q U AT O R

Altair

+10o

+20o

+20o

+30o

+30o

PISCES

EQUULEUS

AQUILA

+10o

–20o CETUS

LIBRA

C PTI

SCUTUM

VIRGO

0o

–30o

Antares

HYDRA

–20o

SCULPTOR

Fomalhaut

+10o

SERPENS CAPUT

DELPHINUS SAGITTA

Arcturus

D E C L I N AT I O N

–40o

PEGASUS

+20o

COMA BERENICES VULPECULA

+30o

CORONA BOREALIS HERCULES LYRA

+40o

+40o

+40o

Vega

BOOTES

+50o

LACERTA

Deneb

+50o

EAST

CANES VENATICI ANDROMEDA

+50o

CYGNUS

DRACO

CASSIOPEIA

URSA MAJOR

MAY

+60o

+60o

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

+60o

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lat­i­tude, the celes­tial equator crosses the north­ern sky 35  degrees away from the zenith, or 55 degrees above the north­ern horizon. Some notable stars, such as the ‘belt stars’ of Orion (see Sky Chart 6) or those of Virgo (Sky Chart 9), lie very close to the celes­tial equator, and can there­fore show you where it can be found. The dotted line on the map, curved so that it is some­times north and some­times south of the celes­tial equator, is the eclip­tic, which marks the annual path of the Sun against the back­ground of the stars. The eclip­tic cuts the equator in two places, known as the equi­noxes, and reaches its maximum dis­tances north and south of the equator (231 ⁄ 2 degrees) at two other points, known as the sols­tices. Along the way, the eclip­tic passes through 12 con­stel­la­tions, pop­u­larly called the Signs of the Zodiac. See pages 12–13 for more on these impor­tant matters. Also shown curving north and south of the equator (but going much further north and south than the eclip­tic does) is a broad and patchy band of light with the popular name of the Milky Way. See page 18 for more on this.

The grid of the sky: (a) declination On maps of the Earth, we find our way around by using the grid of lines marking lat­i­tude and lon­gi­tude. The same is true with maps of the sky, with a few dif­fer­ences. Distance north and south of the celes­tial equator, the equiv­a­lent of lat­i­tude on Earth, is known as dec­li­na­tion (dec. for short) and increases from zero degrees on the equator to 90 degrees at the poles. We do not speak of north or south in describ­ing dec­li­na­tion. Instead, dec­li­na­tion north of the celes­tial equator is listed as pos­i­tive, dec­li­na­tion south is neg­a­tive. On most of the star maps in this book, lines of dec­li­na­tion are spaced 10 degrees apart. Declination tells a lot about how the stars appear in the night sky. Stars lying close to the celes­tial equator (such as the Belt Stars of Orion or some of the stars of Virgo) always rise and set due east and west and are above the horizon for around 12 hours at a stretch. Stars north of the equator (that is, with pos­i­tive dec­li­na­tions) rise north of east, set north of west and are visible for less than 12 hours from rising to setting. Arcturus, Vega or the stars of Gemini are exam­ples. The further north the stars (the more pos­i­tive their dec­li­ na­tion) the lower they are in the sky (even when cross­ing the merid­ian) and the briefer their appear­ances. The most ­north­erly stars will not rise at all when viewed from south of the equator. Your lat­i­tude sets the limit. From our popular viewing spot at 35 degrees south, stars with more than plus  55 degrees dec­li­na­tion are always out of sight. These include famous north­ern con­stel­la­tions such as the Big and Little Bears. Stars south of the equator (that is, with neg­a­tive dec­li­na­ tions) rise south of east, set south of west and are above the horizon for at least 12 hours at a time. Fomalhaut, Canopus or the stars of Scorpius dem­on­strate this. The further south a star lies (that is, the more neg­a­tive its dec­li­na­tion) the longer

it stays in view. Many never set. From 35 degrees south lati­ tude, stars south of minus 55 degrees dec­li­na­tion are always in view (if the sky is clear). So we can always see the Southern Cross and the Pointers, though you will find them in dif­fer­ent parts of the sky depend­ing on the time of the night and the year.

The grid of the sky: (b) right ascension The celes­tial equiv­al­ent of lon­gi­tude, the posi­tion of an object east or west of a fixed point, is right ascen­sion (RA for short). There are some major dif­fer­ences from ter­res­trial lon­gi­tude. Right ascen­sion is meas­ured in hours, not degrees, though each hour is equiv­a­lent to 15 degrees. Unlike lon­gi­tude, which is meas­ured both east and west, right ascen­sion increases in only one direc­tion, that is, to the east, running from zero hours to 24 hours in one circuit of the sky. The start­ing point for the meas­ure­ment of lon­gi­tude (zero degrees) on Earth is the Greenwich Observatory in London. On the celes­tial sphere the meas­ure­ment of right ascen­sion starts where the eclip­tic cuts the celes­tial equator near the western end of the con­stel­la­tion of Pisces the Fish (one of the signs of the zodiac: see page 13). This point is called the vernal equinox. During its yearly migra­tion along the eclip­tic, the Sun reaches this point around 21  March, which is the start of spring in the Northern Hemisphere. A line north and south across the sky passing through the vernal equinox there­fore marks zero hours of right ascen­sion. Similar lines through the other equinox and the two sol­tices mark 12, 6 and 18 hours of right ascen­sion. On Map A and on most maps in this book RA is marked every hour. At any time only half the total sky area shown on the map will be visible, the sector cov­er­ing six hours of right ascen­sion either side of the stars then cross­ing the merid­ian. The dates at the bottom of Map A indi­cate the month of the year when the stars on each line of right ascen­sion will be on or close to the merid­ian (that is, highest in the sky) at nine in the evening.

Sun and Moon Dominating the sky by day and night are the two bright­est extra-terrestrial objects, the Sun and the Moon. Their move­ ments deter­mine how much of the rest of the uni­verse we are per­mit­ted to see. For instance, the stars are not fully visible until the rota­tion of the Earth has taken the Sun a suit­able dis­ tance (some 18 degrees) below the horizon and the sky has grown dark. At lat­i­tudes around 35 degrees, this point in time (known as the end of astro­nom­i­cal twi­light) is not reached until more than an hour after sunset.

The ecliptic and the zodiac The Sun also appar­ently con­trols which stars and con­stel­la­ tions will become visible once it sets. While the stars behind the Sun will not be visible in its glare, you can figure out

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where the Sun is among the stars by looking at the stars that rise just before the Sun rises, or set just after it sets. The yearly journey of the Earth around the Sun causes the Sun, as seen from Earth, to move against the back­ground of the stars, tracing out the eclip­tic. Astronomers long ago divided the stars along this path into 12 con­stel­la­tions, and each of these is now assigned a stretch of sky 30 degrees long. The number of these special constel­ lations equals the number of months in the year, and they make up the 12 signs of the zodiac, which means ‘the proces­ sion of the animals’. All but one of these con­stel­la­tions rep­re­ sent living things. In the order they are usually given, they are: Aries the Ram, Taurus the Bull, Gemini the Twins, Cancer the Crab, Leo the Lion, Virgo the Young Maiden, Libra the Scales, Scorpius the Scorpion, Sagittarius the Archer, Capricornus the Sea-Goat, Aquarius the Water-Carrier, Pisces the Fish. The Sun takes a month to pass through each zodiac con­ stel­la­tion, and during that month the Sun is said to be ‘in’ that con­stel­la­tion. In this regard, a slow shift is evident in the machin­ery of the cosmos, known as the pre­ces­sion of the equi­noxes. Nowadays, the Sun is among the western stars of Pisces around March 21 at the start of the north­ern spring. But 2000 years ago this impor­tant date was marked by the Sun moving into Aries, one sign to the east. The astrol­o­gers and casters of horo­scopes still allo­cate the sign of Aries to the month begin­ning 21 March. Nowadays, the summer sol­stice (Midsummer’s Day) north of the equator arrives when the Sun enters Gemini. But 2000 years ago, the sol­stice lay in Cancer (hence the now out­dated term Tropic of Cancer). Two thou­sand years earlier still, at the height of Babylonian astron­omy (and astrol­ogy), the sol­stice was hosted by Leo. This is a likely origin of the asso­ci­a­tion between the lion and royalty (for more on this see the text to Sky Chart 16).

Sky change throughout the year The move­ment of the Sun along the eclip­tic places it about 1 degree further east rel­a­tive to the sur­round­ing stars each day. Conversely, the stars are about 1 degree further west rel­a­tive to the Sun every day. Since the posi­tion of the Sun con­trols our reck­on­ing of time (traditionally, noon or twelve midday on the clock marks the time when the Sun is highest in the sky), this shift causes the stars to rise and set earlier each day (accord­ ing to the clock) by about four minutes. This difference gives rise to the concept of ‘sidereal time’. That is, time according to the stars rather than to the Sun.You can explore this in more detail on pages 21–22. The net result of all this is a slow change in the appear­ance of the night sky through­out the year, on top of the faster change which occurs hourly through­out the night. From week to week, new stars and con­stel­la­tions are found rising in the east as the Sun goes down while those near the western horizon are stead­ily swal­lowed up by the sunset. Four minutes a day makes two hours a month and six hours in three months. So stars which are rising in the east at sunset in January will be cross­ing over­head at sunset in April. In July they

will be setting with the Sun and will not be visible again in the night sky for a few months, and then only in the ‘small hours’. This move­ment also affects stars high in the south­ern sky, stars that never set. At a given time each evening, those stars will be found posi­tioned about 1 degree further clock­wise. One degree a day amounts to 90 degrees in three months. So the Southern Cross, which is high in the south-east in the early evening in May, will be high in the south-west three months later. In November it will be low in the south-west (and almost upside-down), while an early February evening will find it low in the south-east but rising.

The moving Moon The move­ments of the Moon, and the changes in its appear­ ance, are the most obvious of all the night sky hap­pen­ings. For this reason many ancient cal­en­dars were based on the Moon; the Hebrew and Islamic cal­en­dars still are, with each month (‘moonth’) begin­ning with the very first appear­ance of the Moon as a thin cres­cent after sunset. The move­ment of the Moon among the stars of the zodiac is the result of its orbit of the Earth from west to east (the same direc­tion as the Earth turns on its own axis). The monthly cycle beings with the Moon invis­ible against the glare of the Sun (the strict meaning of the term New Moon). Within a day or two it appears as a thin cres­cent (what is com­monly called ‘a new moon’) close to the western horizon after sunset. As the days go by, the Moon moves stead­ily east among the stars, along a line lying close to the eclip­tic. Each night it is posi­tioned about 12 degrees (a little more than a fist width at arm’s length) further east, taking about two and a half days to pass through each zodiac sign. At the same time, its rising occurs about 50 minutes earlier each day, amount­ing to a change of 24 hours in the full month, and its appear­ance alters as it passes through its cycle of phases. Since one side of the Moon is fully lit at any time, the chang­ing phase of the Moon is the result of a chang­ing rela­tion­ship in space between the Moon, the Sun and the Earth. This rela­tion­ ship, driven mostly by the Moon’s monthly orbit of the Earth, permits us to see a chang­ing amount of the lit face. The cycle of phases begins at New Moon when the Moon is on the sunward side of the Earth and we can see only the side in dark­ness. Day by day, the Moon moves further away from the Sun in the sky, and its cres­cent broad­ens (a waxing cres­cent). Worth looking for on a very young Moon is the effect of earth­shine. Light reflected by the Earth onto the unlit portion causes it to glow faintly (‘the Old Moon in the Young Moon’s arms’). More than a few days after New Moon this sight is lost in the growing glare of the sunlit portion After seven days, the Moon reaches First Quarter, with the left-hand half of its face lit, rising at noon and setting at mid­ night. Another seven days as a waxing gibbous moon brings it to Full Moon, rising as the Sun sets and setting as it rises. The Moon then lies oppo­site the Sun in the sky, and its lit face is fully visible. Thereafter the gibbous moon wanes, reach­ing Last Quarter after another seven days. The right-hand side is lit and Moonrise

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occurs at mid­night. Seven more days as a waning cres­cent brings another New Moon. Just before it becomes new, the Moon is visible as a thin cres­cent low in the eastern sky before dawn. The major impact of the Moon on night sky viewing comes from the light it sheds, which can dom­i­nate the light of the stars. Fainter sights such as the Milky Way are lost in its glare. The best time to view the stars is when the Moon is absent or merely a thin cres­cent. For early evening sky­watch­ ing, that means the period from a few days after Full Moon through until a day or two after New Moon.

Eclipses From time to time as the Moon orbits the Earth, it passes through our shadow. Such an eclipse of the Moon (or lunar eclipse) can occur only at Full Moon, though at most Full Moons there is no eclipse, as the Moon passes above or below the cone of shadow the Earth casts into space. If the eclipse is total (that is, the Moon passes through the centre of the Earth’s cone of shadow), the Moon darkens to a strik­ing coppery-red colour. Superstitious people in ancient times referred to the Moon ‘turning to blood’. On other occa­sions, only some of the Moon will be blacked out. Lunar eclip­ses can be seen from wherever the Moon is above the horizon at the time of the eclipse, which nor­mally lasts several hours. The equiv­a­lent pos­sibil­ity at New Moon is for an eclipse of the Sun (or solar eclipse) with the Moon passing directly in front of the Sun and cutting off its light for a few minutes. Since these are obvi­ously daytime events, they do not concern us here, other than to say that during a total solar eclipse, the sky does darken enough for the stars to appear. In any one year, up to half a dozen eclip­ses of the Sun and the Moon will occur, though few if any will be total.

The face of the Moon Even with the naked eye, the mottled face of the Moon is inter­est­ing. The view through binoc­u­lars or a small tele­scope turns the inter­est into fas­ci­na­tion. The most obvious mark­ings are large dark areas called by the ancients the mare or ‘seas’, for so they thought them to be. We now know them to be vast almost smooth plains of vol­canic rock, but the old names persist. A fertile imag­i­na­tion can turn them into the fea­tures of the face of the ‘man in the Moon’ or into other images (such as a rabbit) in other cul­tures. Though smaller, some of the craters and moun­tain ranges are strik­ing, espe­cially when close to the ter­mi­na­tor, the line divid­ing the lit and unlit por­tions of the Moon. Along this line, an observer on the Moon would see the Sun rising or setting, and the low Sun casts long shadows, greatly enhanc­ ing the relief. The high­lands are very old; the craters formed more recently by the impact of aster­oids or comets. Because the Moon spins on its axis in the same time inter­ val as it orbits the Earth, it always keeps the same face turned towards us. From Earth we cannot see most of the ‘far side’ of the Moon. However, space­craft have sent back images of the hidden side, showing it to be much like the face we see

though with many fewer mare. It is not correct to call the far side the ‘dark side’, since through­out the month, it receives as much light as the side we see. Map B iden­tifies the main mark­ings on the Moon’s surface, as revealed at Full Moon. The craters carry mostly the names of famous people, such as ancient and modern astronomers or other scientists, or philosophers. The largest of the craters are a hundred kilometres or more across. The diagram is ­oriented as the Moon is when seen high in the north­ern sky with the naked eye or with binoc­u­lars (that is, the North Pole of the Moon is at the bottom). If the Moon is rising, turn the chart clock­wise (so that north is on the left). If the Moon is setting, turn it anti-clockwise. If you are using a tele­scope (which inverts the view), turn the chart upside down.

The planets From time to time, you will notice among the stars other points of light that do not hold their posi­tions as the regular stars do, and which are there­fore not marked on any star map. The ancient Greek astron­o­mers called these ‘planetos’ or ‘wan­der­ing stars’, from which comes our word planet. Five of these were known in ancient times (Mercury, Venus, Mars, Jupiter and Saturn), and two more (Uranus and Neptune) have since been found using the tele­scope. Pluto, discovered in 1930, was long regarded as the ninth planet but recently lost that status. The ancients were puzzled by these objects and their often strange beha­vi­our. They thought they were living things, even man­i­fes­ta­tions of the Gods, and named them accord­ingly. We now know that planets are cold, rocky or gaseous spheres in orbit around the Sun, as is our Earth. Two of the planets (Mercury and Venus) are closer to the Sun than we are and orbit it more quickly (the inner planets); the others lie outside the Earth’s orbit and travel more slowly (the outer planets). Some are larger than the Earth, some smaller. Like the Moon, they shine only by the reflected light of the Sun, unlike the true stars which make their own light. A planet’s bright­ ness is a measure of its size (Jupiter is bright because it is big), its near­ness (Venus is bright because it is close) or the nature of its surface (Venus again because it is covered with highly reflec­tive cloud).

The movements of the outer planets Generally speak­ing, these planets behave as do the Sun and the Moon.They appear to move east­wards along paths that lie close to the eclip­tic, passing through the zodiac con­stel­la­tions one by one. Mars moves most quickly, taking just over two years to com­plete one circuit of the sky and spend­ing two months in each zodiac con­stel­la­tion. Jupiter, with a 12-year journey around the eclip­tic, takes a year to pass through one sign. The others travel more slowly still, with Saturn spend­ing two and a half years, Uranus seven years and Neptune 14 years. This simple picture is com­pli­cated by retrograd­ing. Over a period of some months in every year a planet ceases its usual

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S Blancanus Scheiner Clavius Vlacq

Cuvier

Pitiscus

Longomontanus Faraday

VALLIS RHEITA

Metius

Fabricius

Snellius

Langrenus

E

TAI AL

Goclenius

Mädler

Gutenberg

MONTES RIPHAEUS

Herschel

Lansberg Godin

Ritter

SINUS AESTUUM

MARE VAPORUM Manilius

Procius

Plinius Vitruvius

Macrobius

Menelaus

MARE SERENITATIS

Cleomedes Burckhardt

Reinhold

Triesnecker

Agrippa Julius Ceasar

MARE TRANQUILITATIS

TE

S

EN AP

NE NI

Marius

S

MONTES CA RPATES Aristarchus Timocharis

OCEANIS IMBRIUM

Bürg Endymion

Eudoxus

Aristoteles

ES ALP LIS AL VAL PE S

S

Pico

SINUS IRIDUM

M Plato

MARE FRIGORIS

VALLIS SCHRÖTERI

Mairan

RA

Cassini

TE

Herodotus Struve

Euler Lambert

JU

Atlas

Seleucus

Wallace

Aristillus

ON

W

Eratosthenes

Archimedes

M

Hercules

Riccioli

OCEANIS PROCELLARUM Kepler

Franklin Cepheus

Grimaldi

Copernicus

Autolycus Posidonius

Geminus

Messala

Crüger

MARE COGNITUM

Delambre Sabine Maskelyne

Mersenius

Gassendi

Bullialdus

Ptolemaeus Hipparchus

Tarantius

MARE CRISIUM

MARE HUMORUM

Alpetragius Alphonsus

Albategnius

Capella

Apollonius

Condorcet

Arzachel

Isidorus

MARE FECUNDITATIS

Firmicus

MARE NUBIUM

Vieta

Campanus

Purbach

Abulfeda Cyrillus Theophilus

Mercator

Pitatus

Playfair

Catharina Tacitus

MARE NECTARIS

Cichus

Regiomontanus G

Sacrobosco

Capuanus

Walter

Apianus

ES

Vendelinus

Fracastorius

Wurzelbauer

Werner

Aliacensis

Zugat

RU P

Santbech Colombo

Gauricus

Piccolomini

Stevinus

Schickard

Wilhelm

Stöfler

Maurolycus

Rabbi Levi

Rheita

Petavius

Tycho

Fabricius

M O N

Furnerius

Phocylidus

Schiller

.

SINUS RORIS

Bianchini Harpalus

Strabo W. Bond

N Map B. The main features of the surface of the Moon east­erly motion (that is, it becomes sta­tion­ary), moves back­ wards (that is, towards the west), stops again (becomes ­sta­tion­ary a second time) and then resumes its east­ward course. The further away a planet is, the longer retrograd­ing lasts, but the smaller the dif­fer­ence it makes to the posi­tion of the planet. For Mars, retrograd­ing lasts only two months, but the out­er­most planets spend half the year moving back­wards. However, Mars swings through a couple of constellations as it retrogrades, while Saturn rarely leaves the constellation it was in when it became stationary. This odd beha­vi­our is only appar­ent, not actual. In reality, the planets move stead­ily onwards in their orbits at an almost

steady pace. Retrograding is due to the fact that the Earth, moving more quickly in its orbit than the planets outside it, over­takes them ‘on the inside lane’, so that for a time they appear to move back­wards. You see the same thing when out driving. As you pass another car, it appears to move back­wards rel­a­tive to the scenery. Roughly halfway through its move back­wards, the planet reaches a point exactly oppo­site the Sun in the sky (that is, it comes to oppo­si­tion). At oppo­si­tion, the planet rises around six in the evening and crosses the merid­ian at mid­night. The outer planets are bright­est and appear largest in a tele­scope at oppo­si­tion, as they are then closest to the Earth, though the ­­15

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vari­a­tion is more notice­able with Mars than with the more distant planets. About six or seven months after oppo­si­tion, the planet dis­ ap­pears behind the Sun for a while and cannot be seen (that is, it reaches con­junc­tion with the Sun). Before con­junc­tion, the planet will be an evening star (that is, visible above the western horizon after sunset). After con­junc­tion, the planet becomes a morning star (visible in the east before dawn).

The movements of the inner planets The move­ments of Mercury and Venus against the back­ground of the stars are com­pli­cated by the fact that they never get very far away from the Sun (Mercury a maximum of about 27 degrees, Venus a maximum of less than 50 degrees). These planets there­fore never come to oppo­si­tion and are never visible in the mid­night sky. They accom­pany the Sun in its yearly journey through the zodiac, being some­times ahead of  the Sun in the sky (that is, with eastern elon­ga­tion), and  some­times lagging behind (that is, with western ­elongation). The inner planets have two con­junc­tions with the Sun during each orbit, one at which the planet passes the Sun on the near side (infe­rior con­junc­tion), the other with the planet passing the Sun on the side away from the Earth (super­ior con­junc­tion). Between super­ior con­junc­tion and infe­rior con­junc­tion, the planet is an evening star. Between infe­rior con­junc­tion and super­ior con­junc­tion, it is a morning star. Like the Moon, Mercury and Venus both show phases when viewed with tele­scopes, moving from thin cres­cent to full disc and back again during each orbit. This, com­bined with great vari­a­tion in their dis­tances from us, causes the inner planets to vary greatly in appar­ent size and bright­ness. Maximum bright­ness occurs close to the time of maximum elon­ga­tion east or west.

Which planet? If you find a planet among the stars but are not sure which one it is, the appli­ca­tion of a few simple rules will sort the matter out Mercury is never easy to find, since it stays close to the Sun and to the twi­light, and is there­fore rarely seen against a dark sky. The give­away is its rapid move­ment among the stars, ­shift­ing its posi­tion mark­edly from night to night rel­a­tive to nearby stars. This is appro­pri­ate. The planet was named after the fleet-footed mes­sen­ger of the gods in ancient Roman legend, and returns to the same posi­tion in the sky (say to maximum eastern elon­ga­tion, at which time it is highest in the sky at sunset) every three months. Venus on the other hand is very hard to miss, espe­cially as ‘the evening star’, blazing in the west high above the sunset. (Any planet can become an evening star, of course, but Venus is the acme.) Showings of Venus as an evening star are spaced about eight months apart. It rises up to three hours before the Sun and sets up to three hours after, and so can clear the

t­wi­light. At maximum mag­ni­tude it out­shines every­thing other than the Sun and Moon, and can cast a shadow on a moon­less night. Its naming, after the Roman goddess of love and beauty, seems most appro­pri­ate. The dis­tinc­tive red or pink colour of Mars, the result of it being covered by desert, was likened by the ancients to a drop of blood and so it was named after the god of war. Unlike the redder stars (such as Antares) with which it may be com­ pared, Mars moves among the stars, pushing east through one zodiac sign every two months. At oppo­si­tion, small tele­scopes may glimpse it as a coloured disc, with perhaps smudgy dark mark­ings and a touch of white at the poles. Jupiter is the largest planet and can get quite bright, though not as bright as Venus. It is there­fore easy to spot, espe­ cially in con­stel­la­tions with dimmer stars. Its colour is almost white, and its move­ment is stately, as befits a planet named after the king of the Roman gods. It takes a year to pass from one zodiac sign to the next. In a small tele­scope, Jupiter will show as a dis­tinct disc, with perhaps some streaky mark­ings. Saturn moves the most slowly of the naked-eye planets, so sug­gest­ing a link to the Roman god of old age. It will be found within the con­fines of a single zodiac con­stel­la­tion for almost three years. It may be found any­where along the eclip­tic, and its off-white colour is an added source of iden­tifi­ca­tion. The chief attrac­tion of Saturn is its system of rings, which can be seen in small tele­scopes. There is a fas­ci­nat­ing link between the planets and the old pseudo-science of alchemy, the fore­run­ner of modern ­chem­is­try. In ancient lore, each hea­venly object was linked to one of the seven metals known at the time, and the same symbol used for both the metal and the planet. So Mercury was linked to the metal mercury, Venus to copper, Mars to iron (its rusty redness helped there), Jupiter to tin and Saturn to lead. The Sun (gold) and the Moon (silver) were also part of this scheme. We can also con­tem­plate the way the names of the planets are imbed­ded in our lan­guage, such as in the days of the week (for example, Saturday was orig­i­nally Saturn’s Day), and in words like mer­cu­rial, vene­real, martial, jovial (Jupiter was also called Jove) and sat­ur­nine.

The waltz of the planets The move­ment of the various planets through the zodiac at dif­fer­ent speeds pro­duces an endless variety of events, easily tracked with the naked eye. Among these are numer­ous con­ junc­tions, with planets drawing close to each other (often within a few degrees), to bright stars (such as Regulus, Pollux, Spica and Antares, which lie close to the eclip­tic) or to the Moon. Conjunctions with the Moon are most ­inter­­­est­ing when the Moon is a cres­cent, and there­fore not overly bright. At times three or even four planets will be found together in the same part of the sky, and their move­ments from week to week or even night to night are fas­ci­nat­ing to watch. The Moon will some­times occult a planet or star, that is, pass in front of it. It is inter­est­ing to watch for the dis­ap­pear­ ance or re-emer­gence of the object, again espe­cially if the

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Table 3. Main meteor showers

Normal limits

Maximum

Peak rate (average) per hour

Quarantids (in Bootes) Lyrids Eta Aquarids Delta Aquarids Perseids Orionids Taurids Leonids Geminids

Jan. 1–6 Apr. 19–25 May 1–10 July 15 – Aug. 15 July 23 – Aug. 20 Oct. 16–27 Oct. 20 – Nov. 30 Nov. 15–20 Dec. 7–15

Jan. 3 Apr. 22 May 6 July 29 Aug. 12 Oct. 22 Nov. 5 Nov. 17 Dec. 13

60 15 hr 30 min/50 10 18 hr 10 min/32 35 22 hr 20 min/01 20 22 hr 39 min/17 75   3 hr 08 min/58 25   6 hr 27 min/15 10   3 hr 47 min/14 10 10 hr 11 min/22 75   7 hr 31 min/32

Moon is a cres­cent. Details of con­junc­tions, occul­ta­tions and other events (such as eclip­ses) can be found in pub­li­ca­tions com­piled by astro­nom­i­cal soci­eties (such a listing is called an ephem­e­ris) and on sale in astron­omy supply shops. You can also refer to Appendix B, which gives the posi­tions of four of the five naked-eye planets each month for the next ten years, together with details of some sig­nif­i­cant plan­e­tary events.

Satellites, comets, meteors, minor planets The solar system, the region of space con­trolled by the gravity of the Sun, con­tains much more than the planets. Many of these other objects are night-sky sights. Satellites. All the planets except Mercury and Venus have ‘moons’ orbit­ing them, though most of these are very faint when viewed from Earth (mag­ni­tude 10 or fainter). The easiest to pick out are the four largest sat­el­lites of Jupiter (Io, Europa, Ganymede and Callisto). With mag­ni­tudes at oppo­ si­tion between 4.6 and 5.7 these can be seen with the naked eye if con­di­tions are right, and are an easy target for binoc­u­ lars. They orbit Jupiter with periods of between one and a half and 17 days, pro­duc­ing a con­stantly varying dis­tri­bu­tion of bright points on either side of the planet. The pre­dicted posi­ tions of the moons are pro­vided in an ephem­e­ris. The moons of Jupiter line up on either side of the planet more often than you might expect. This is the result of the strong gravity of Jupiter locking the orbits of the three inner moons into a res­o­nance. Each time Ganymede com­pletes one orbit, Europa goes round exactly twice and Io exactly four times. Saturn’s bright­est sat­el­lite, Titan (period 16 days), is within reach of binoc­u­lars at maximum mag­ni­tude, 8.3, with Rhea (period four and half days) also a pos­sibil­ity at maximum mag­ni­tude, 9.7. Comets. Comets are icy bodies trav­el­ling around the Sun in long thin orbits, becom­ing bright and devel­op­ing the char­ ac­ter­is­tic tail when near the Sun. A few become spec­tac­u­lar naked-eye objects, but the arrival of those is unpre­dict­able. A bright comet may take thou­sands of years to return if it comes back at all.

Radiant (RA/Dec)

Of the reg­u­larly return­ing comets, only the famous Halley’s Comet is bright enough to make a real showing to the naked eye, but a number of others are worth track­ing down with binoc­u­lars. Again, you should refer to an ephem­ e­ris for details. Meteor showers. As comets orbit the Sun, they leave behind a trail of dust and small frag­ments. When the Earth passes through this trail, some of the rubble is swept up by gravity and burns up in the Earth’s atmos­phere, appear­ing as bright streaks of light across the sky. Such meteor showers (com­ monly dubbed ‘falling stars’ or ‘shoot­ing stars’) emerge from par­tic­u­lar points in the night sky (their radi­ants) at certain times of the year. A list of the main showers is given in Table 3, and ref­er­ence is made to them in the text beside the Sky Charts. At the times of year the various showers occur, the constellations hosting them do not rise until late, and so the showers can normally be seen only in the small hours. Minor Planets. Often called aster­oids, these are small rocky bodies orbit­ing the Sun. There are most likely hun­dreds of thou­sands of them, but most are small, a few hundred kilo­ me­tres at most. Most lie between Mars and Jupiter in the aster­oid belt. The largest, Ceres, is only 1000 km across. The bright­est is Vesta, which can reach mag­ni­tude 5.2 and so be a naked-eye sight on a clear dark night. More are visible with binoc­u­lars or a small tele­scope, and the loca­tions of the bright­est among the stars are given in an ephem­e­ris.

A variety of sights The night sky has more to offer than indi­vid­ual stars and planets. Many other sights may be glimpsed with the naked eye, but all benefit from the use of binoc­u­lars or a small tele­ scope (you will do even better with a large tele­scope!).

Stars get together In many areas of the sky, the stars cluster together, often pro­ vid­ing a contrast with their varied colours. Some of these are open clus­ters, with ample space between rel­a­tively small ­­17

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numbers of stars. Such clus­ters, which are com­monly only 10 or 20 light years across at most, contain from as few as 10  stars to as many as 500, all orig­in ­ ally formed together from the one gas cloud. The Pleiades or ‘Seven Sisters’ in Taurus (there are actu­ally more than 30 stars in this cluster), Praesepe or ‘the Beehive’ in Cancer, and the Jewel Box, hard by the Southern Cross, are all notable exam­ples, but this book will refer you to dozens of others. Far more thickly packed with stars are the glob­u­lar clus­ ters, with up to a million stars crowd­ing together like bees around a honey pot. These clus­ters are huge balls of stars, tens or even hundreds of light years across, and the stars within are on average about a light year apart. Globular clus­ters are in general both very old (con­tain­ing some of the most ancient stars known) and very remote (many lying 10,000 or 15,000 light years distant). Omega Centauri (again close to the Southern Cross) and 47 Tucanae near the Small Magellanic Cloud are among the finest such clus­ters in the sky. We should add that even through a telescope it is not easy to appreciate the true form of a globular cluster; most of them look like fuzzy stars.

The Milky Way The Milky Way, best seen on a clear dark night, appears as a faint band of light, winding its way around the sky and passing through or close by a number of con­stel­la­tions, includ­ing Crux,Vela, Carina, Canis Major, Orion, Auriga, Perseus, Cygnus, Aquila, Sagittarius and Scorpius. Ancient observ­ers thought it was a stream of milk from the breast of some sky goddess and used the term galaxy from the Greek for ‘milk’. Since the time of Galileo (though some Greeks 2000 years before guessed at the truth) we have known it is in fact made up of bil­lions of stars, so distant and so closely clus­tered together that the unaided eye cannot sep­ar­ate them. Binoculars or a tele­scope will quickly reveal many of those stars. The Milky Way is widest and most dense between Scorpius and Sagittarius, where the most distant observ­able stars are about 30,000 light years away. The appear­ance of the Milky Way is the con­se­quence of the Sun and its planets being located within a vast wheel-shaped con­gre­ga­tion of stars, now known as the Milky Way galaxy (or simply ‘the galaxy’). The hub of this system lies beyond the stars of Scorpius and Sagittarius, and the rest of the Milky Way is simply the con­se­quence of looking across the galaxy along its longest dimen­sion. Modern reck­on­ing makes our galaxy about 100,000 light years in diam­et­er, about 10,000 light years thick in the centre, and about 3000 light years thick out in the outer suburbs where we are (some 30,000 light years from the hub). It con­tains at least 200 thou­sand million stars, 10 per cent of which are similar in size and tem­per­a­ture to our Sun. The axis of the ‘wheel’ of our galaxy can be taken to cut the celes­tial sphere at the North Galactic Pole (NGP) and South Galactic Pole (SGP) (just as the Earth’s axis cuts it at the North and South Celestial Poles). The NGP lies in Coma Berenices, the SGP in Sculptor. The Sun and its planets lie

slightly above the plane of the Milky Way, so we see more stars (and more bright stars) looking south than looking north. That is one reason why the skies of the Southern Hemisphere are so bril­liant!

Nebulae, dark and bright Here and there along its length, the Milky Way is divided by dark lanes and broken by patches appar­ently devoid of stars, for example, in the Scorpius/Sagittarius region and in Cygnus. In truth, vast clouds of dust hanging in space block the light from the stars of the Milky Way in these regions. Other such dark nebulae (‘nebula’ is Latin for ‘a cloud’) include the Coal Sack beside the Southern Cross and the spec­tac­u­lar but elusive (for small tele­scopes anyway) Horsehead Nebula in Orion. There are also a great many bright nebulae, patches and wisps of glowing gas. Some of these are ‘star nurseries’, patches of gas glowing pink from the energy of newly born stars within them. The Great Nebula in Orion is one such star nursery, as are the Trifid and Lagoon Nebulae front­ing the Milky Way near Sagittarius. Indeed, emis­sion nebulae of this kind are mostly found along the Milky Way, espe­cially looking towards the galac­tic centre. Some nebulae asso­ciated with young stars are blue rather than pink. This is the result of blue light from the young hot stars being scat­tered by clouds of dust. The blue wisps of gas sur­round­ing the 50-million-year-old Pleiades form such a reflec­tion nebula. A warning about the colours. You will see them in photo­ graphs but, alas, not with your eye directly (even with binoc­ u­lars). At low light levels, the human eye picks up little colour, and most of the nebulae will appear white with a green­ish tinge. They are still worth seeking out. A few nebulae mark the loca­tions of stars in old age, ‘red giant’ stars which have shed their outer layers to form glowing rings of gas, some­times mis­lead­ingly called plan­e­tary nebulae (they have nothing to do with planets). The Ring Nebula in Lyra the Harp is an example. Others are ‘star cemeteries’, each marking the spot where very large stars at the end of their brief violent lives have blown them­selves to pieces as super­no­vas. The Vela Nebula and the Crab Nebula in Taurus lie in that cat­e­gory, though both are hard to resolve into anything meaningful other than in large telescopes. The Crab Nebula is the remnant of the super­nova recorded by Chinese astron­o­mers in 1054 AD.

Nebulae beyond Still other nebulae are vastly larger and more distant, since we now know that they are com­plete star systems (gal­ax­ies) lying beyond our own. The two Clouds of Magellan, which appear as faint patches of light in the south­ern sky, are the nearest of these, being some 200,000 light years away. They are rel­a­ tively small and are essen­tially ‘satellites’ of our own Milky Way galaxy. Binoculars will reveal the strik­ing Tarantula Nebula in the Large Magellanic Cloud, letting you glimpse the spidery outline that provoked the name.

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The Andromeda Galaxy, a naked-eye object in the ­north­ern sky, is the nearest of the large exter­nal gal­ax­ies, being two million light years distant. Such ‘island universes’, each con­ tain­ing bil­lions of stars, are thickly clus­tered in certain areas of the sky, most notably in the con­stel­la­tions of Virgo, Coma Berenices and Canes Venatici. Numbers of gal­ax­ies are also found in Fornax, Sculptor, Leo and Perseus. These con­stel­la­ tions lie close to the Galactic Poles. Galaxies are not found near the Milky Way as the dust clouds and thickly clus­tered stars hide them from view. The various clus­ters and nebulae have been cat­a­logued several times. The oldest such effort was by the eight­eenth-

century French comet-hunter Charles Messier, who noted over 100 fuzzy objects likely to be con­fused with comets. His list is still often used. The Crab Nebula is M1, the Lagoon Nebula M16, the Orion Nebula M42, Praesepe M44, the ‘Sombrero Hat’ galaxy M104. Most of the Messier objects are in the north­ern part of the sky. More recent and more com­pre­hen­sive is the New General Catalogue (NGC) first com­plied over a hundred years ago with thou­sands of entries. Objects listed with an N followed by a number are from the NGC. Other letter–number combina­ tions in this book indicate other catalogues.

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S_Sky_Guide_TEXT_3ed_01.indd 20

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the Skyviews

Using the Skyviews The fol­low­ing 24 Skyviews rep­re­sent the night sky at dif­fer­ent times of the year and dif­fer­ent times of the night. Since the stars on show in the night sky change noticably from hour to hour during the night and week to week through­out the year, it is vital that you choose the right Skyview to use. Each Skyview has been drawn to cor­re­spond with a certain side­real time. Sidereal time is set by the stars, rather than by the posi­tion of the Sun, as in ordi­nary solar time. Whereas a solar day is the period between two noons, that is, between two pas­sages of the Sun across the merid­ian, a side­real day is the time between two suc­ces­sive ‘tran­sits’ of the vernal equinox, or indeed of any par­tic­ul­ar star. Since the east­erly motion of the Sun along the eclip­tic causes the stars to rise earlier each day by about four minutes

by the clock, a side­real day is shorter than a solar day by four minutes. Put another way, the sidereal clock runs faster than the solar clock, gaining four minutes a day. Over the year, the difference builds up to a whole day. A year contains 365¼ solar days but 366¼ sidereal days. Put another way, the side­ real clock runs faster than the solar clock, gaining four minutes a day. To work out the side­real time cor­re­spond­ing to your day and time of observ­ing, and there­fore deter­mine which Skyview to use, you can refer to Table 4. Or you can apply the fol­low­ing simple rule: Work out your solar time on a 24-hour clock and add four minutes for each day (or two hours for each month) that has passed since last 21 September. (On 21 September the solar and side­real clocks read the same time.)

Table 4. Choosing the right Skyview (by hour and date of observation) Date 17

Local time (h)* 18

19

20

21

22

23

00

01

02

03

04

05

06

Jan. 5   0   1   2   3   4   5   6   7   8   9 10 11 12 13 21   1   2   3   4   5   6   7   8   9 10 11 12 13 14 Feb. 5   2   3   4   5   6   7   8   9 10 11 12 13 14 15 20   3   4   5   6   7   8   9 10 11 12 13 14 15 16 Mar. 7   4   5   6   7   8   9 10 11 12 13 14 15 16 17 22   5   6   7   8   9 10 11 12 13 14 15 16 17 18 Apr. 6   6   7   8   9 10 11 12 13 14 15 16 17 18 19 22   7   8   9 10 11 12 13 14 15 16 17 18 19 20 May 7   8   9 10 11 12 13 14 15 16 17 18 19 20 21 22   9 10 11 12 13 14 15 16 17 18 19 20 21 22 June 6 10 11 12 13 14 15 16 17 18 19 20 21 22 23 22 11 12 13 14 15 16 17 18 19 20 21 22 23 24 July 7 12 13 14 15 16 17 18 19 20 21 22 23 24   1 22 13 14 15 16 17 18 19 20 21 22 23 24   1   2 Aug. 6 14 15 16 17 18 19 20 21 22 23 24   1   2   3 22 15 16 17 18 19 20 21 22 23 24   1   2   3   4 Sep. 6 16 17 18 19 20 21 22 23 24   1   2   3   4   5 21 17 18 19 20 21 22 23 24   1   2   3   4   5   6 Oct. 6 18 19 20 21 22 23 24   1   2   3   4   5   6   7 21 19 20 21 22 23 24   1   2   3   4   5   6   7   8 Nov. 6 20 21 22 23 24   1   2   3   4   5   6   7   8   9 21 21 22 23 24   1   2   3   4   5   6   7   8   9 10 Dec. 6 22 23 24   1   2   3   4   5   6   7   8   9 10 11 21 23 24   1   2   3   4   5   6   7   8   9 10 11 12 * Subtract one hour from these times during periods of daylight saving.

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An example: to work out si­dereal time at 6 pm on 15 April, convert 6 pm to a 24-hour clock, which gives 18 hours. Add 13 hours (two hours for each of the 6½ months since last 21 September). That totals 31 hours, or 7 hours when reduced by 24 hours. So side­real time at 6 pm on 15 April is 0700 hours and there­fore Skyview 7 is the one to use. To make it easy to decide which Skyview is the right one to use in the early evening (a time you will often be looking at the night sky), each Skyview has a two-week period listed above it (for example, January: weeks one and two). This means that particular Skyview accurately displays the layout of the night sky at 9 pm (taking account of daylight saving if it is in operation) in the middle of the stated fortnight (and will be very close to right throughout the whole period). In other words, for each Skyview, the side­real time given is reached at 9 pm (2100 hours) in the middle of the given period (either the seventh or twenty-first day of the month). The Skyview and cal­cu­la­tion given above let you use the Skyviews at any time of the night. The turning of the Earth causes the posi­tions of the stars and other objects rel­a­tive to the horizon and the zenith to change sur­pris­ingly quickly and notice­ably. You need to be ready to move on to the next Skyview after obser­va­tion for one hour. Each Skyview shows the whole sky visible at the given side­ real time. The outer rim rep­re­sents the horizon. The Skyview should be turned so that the direc­tion in which you are looking is at the bottom. Therefore, if you are looking south, the Skyview should be turned upside-down. The Skyviews are drawn for only one lat­i­tude, namely 35 degrees south. Most of the main pop­u­la­tion centres in the

Southern Hemisphere lie close to this par­allel of lat­i­tude. Observers well to the north or to the south of this lat­it­ude will notice some dif­fer­ences in the vis­ibil­ity of stars near the north­ern and south­ern hori­zons. Each Skyview has marked the South Pole of the sky (around which the sky appears to turn) and the prime merid­ian, namely the line marking 12 hours of right ascen­ sion. Also marked are the celes­tial equator and the eclip­tic, which passes through the stars of the 12 zodiac signs. The other impor­tant feature of these Skyviews is the numbers which occur in the centres of large areas of each. These refer the user to the more detailed Sky Charts later in this book, which contain stars of higher mag­ni­tudes, together with impor­tant sights through binoc­u­lars such as double stars and nebulae. Two expres­sions are com­monly used in the text adjoin­ing each Skyview. One is ‘cross­ing the meridian’. This means a move­ment from the eastern to the western half of the sky. ‘The top of the sky’, used for south­ern stars, also refers to cross­ing the merid­ian, that is, rising as high as pos­sible above the South Pole of the sky. Reference is also made to posi­tions of stars rel­a­tive to the South Pole of the sky in terms of hourly read­ings on an ordi­ nary clock face. So ‘three o’clock’ means due west of the pole, and ‘nine o’clock’ means due east. Remember that these Skyviews show only stars. Bright star-like objects not marked on these Skyviews will almost cer­tainly be planets, espe­cially if they lie close to the eclip­tic. (See page 14.)

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Skyview 1 9 pm, November: weeks three and four Sidereal time 0100 SOUTH Mimosa S CENTAURU

12 h

S

ENT AUR U

CRUX

C

Acrux

A

AR IN

C

LA

LU

PU

3

Rigel K Hadar

CIR

S

CIN

ent

NO

US

RM

LUM GU LE AN TRI STRA AU

MUSCA

VE

A

SC

O

AR

2

APUS

NS ME N

TE

OCTA

NS

South Pole

SA

CT

SC

O

PI

VO PA

HYDR US

pu

U

M

7

ra

S

X

ERID

5

ORION

LEPUS

ANU

FOR

OR

S

NAX

6

US

AQU

ARI

AQU

aut

LPT

Rigel

ENI

PHO

alh

SCU

EAST

RU

Fom

PISCIS US AUSTRIN

CAPRICORNUS

WEST

12

MONOCEROS

Sirius

G

M

BA UM COL

M ELU

M IU OG OL R HO

ar

ern

Ach

PIU

11

CA

ANA

DU S

CO

OS

IS CAN OR J MA

TUC

DO

Ad

RA

ha

DO

no Ca

UM

UL

TIC

1

IN

MIC R

SCU TUM

RE

S

LE

s

PI

IU

C A OR U ST ON RA A LIS

IS PP PU

CHAM

OR

RP

N

AELEO

LA

VO

A

SA GI TT AR IU S

4

e

R ATO

M

EQU

PISCES

US

G

AS

ECLIP

U

TIC

S

Bet

n ra ba de

ad es

PE

Hy

HIN

es

ARIE

14

RI

13

AU

S U

S

20

A

N G

CY

iad

Ple

G

TA

19

Al

US

LP

GIT

TA U

LE

DE

SA

RU

S

UU

elg

EQ

eus

ILA

ir

Alta

ira

US

CET

LUM

NGU

TRIA

LA

CE

ol

Alg

ANDROMEDA

RT A

S

SEU

PER

Magnitudes 0h 5

4

3

2

1

0

brighter

NORTH

The grand summer pano­rama is now unfold­ing in the eastern sky. Orion the Hunter, with its bright stars blue-white Rigel and reddish Betelgeuse, is now clear of the horizon. Taurus the Bull, includ­ing reddish Aldebaran and the Pleiades, lies in the northeast. In the south-east, Sirius, the bright­est of the stars, has risen, marking the larger of the Hunter’s two dogs. A little higher in the south-east lies Canopus, second bright­est of all stars. It lies in Carina, the keel of the ship Argo. Of the other bright stars, Achernar in Eridanus is high in the south, and Fomalhaut in the Southern Fish even higher in the south-west. In the west Altair in Aquila the Eagle is setting. The Great Square of Pegasus stands in the north-west. The zodiac signs visible stretch from Sagitarrius now setting in the south-west, through Capricornus, Aquarius, Pisces and Aries, to Taurus in the north-east.

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Skyview 2 9 pm, December: weeks one and two Sidereal time 0200 SOUTH TAU

CE N

CENTAURUS

CRUX

12 h

RU S

3

Hadar

CIRC

Rigel Kent

Mimosa

INUS

SC

Acrux

OR

MUSCA

INA

CHAMA ELEON

IU

NS

NS

South Pole

SA

MEN

VO PA

IS

HYDRUS

PP PU

TU

CA

M

LU

TIC U

no

p

us

MBA

M

n Procyo

l Rige

US AN

ULE

EQU

a

Mir

CETUS

EQUATOR

CAN MIN IS OR

ER

ID

Sirius

LEPUS

NIX

OE

CA

COLU

HO

ELU

RO

PH

SCULPTOR

ut

Fomalha

CANIS R MAJO

ara Adh

R

DO RA DO

LO

G

IU

M

Achernar

US

PISCIS AUSTRIN US

ORION

NA

RE

M

GR

IU

Ca

M

OP

6

5

EAST

OP

SC

TO PIC

SC

OCTA

LA

PY

LE

S

M ICR O

IUS

AQUAR

AX

RN

FO

7 MONOCEROS

TE

A

APUS

2

IA TL AN

VE

VO

AR

M

LA

4

DU

IN

CO A RO U ST NA RA LIS

CAPRIC ORNUS

AQUILA

WEST

12

XIS

S

LU TRIANGU AUSTRALE

CAR

PIU

SA G IT TA RI US

11

1

ECL

IPTIC

U

S

20

13

NI MI

ge tel

Al

ES

AS

GE

PISC

G

Be

de

ba

ra

n

us

e

US

PE

es

ad

Hy s

iade

Ple

ARIES

S

RU

U TA

14 GA

RI

TRIANGULUM

ol

AU

Alg ANDR

OMED

Magnitudes 5

4

3

2

A

0h 1

0

S

PERSEU

brighter

NORTH

The eastern sky con­tains the great sights: Orion the Hunter marked by the ‘saucepan’ and the bright stars Betelgeuse and Rigel, and in the north-east Aldebaran and the Pleiades marking the eye and the shoul­der of Taurus the Bull. In the east Procyon in the Little Dog has risen, joining Sirius and the stars of Canis Major now well up in the south-east. Also in the south-east is Canopus in Carina, second bright­est of the stars after Sirius. Achernar in Eridanus has crossed the top of the sky, and now lies slightly south-west. Further west and higher is Fomalhaut, the mouth of the Southern Fish. In the north-west, the Great Square of Pegasus is heading for the horizon. Of the zodiac signs, Sagittarius is setting in the south-west and the first stars of Gemini are in view in the north-east. Between those con­stel­la­tions, from west to east, lie Capricornus, Aquarius, Pisces, Aries and Taurus.

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Skyview 3 9 pm, December: weeks three and four Sidereal time 0300 SOUTH S

3

CENT AURU Hadar

12

h

CRU X

AR

A

sa

S

Acrux

CE N

TE

MUSCA

A

RIN

CA

S

Mimo

RU

TA U

CIRCINU

Rigel Kent

N

AELEO

CHAM

SA

GI

OCTAN

IU

S

V

S

2

South Pole

SA

NS

MEN

8

LA

VO

HYDRUS

TU

CA

OR

T

IS PYX

PIC

NA

US

UM

ICUL

US

IS M

OR

INO

R

ION

Rig

el

LEP

HYDRA

R

AX

RN

FO

Sirius

CANIS MAJOR

Adhara

ar

X

CAEL

COLUMBA

ern

GIU M

OL O

HO

UM

Ach

ENI

ut

OR

PHO

LPT

alha

MONOCEROS

PU

O DO

D RA

no Ca

pu

S PPI

s

RET

SCU

Fom

TU

CAN

Mira

S

EQUATOR

S

S

ECL

IPT

IC

se eu lg

n

ra

ba

de

Al

te

SU

U TA

CE

Be

GA

PE

S

RU

PIS

EAST

AR TT

VO PA

GR

AUS PISCIS TRIN US

CE

CER

M

S

DU

PI

AQUARIUS

6

S

NU

IDA

ER

CAN

IU

IN

CO

S

NU

WEST

5

7

yon

OP

4

M OS

IC R UM

OR

RIC

12

Proc

SC

APUS

A EL

A TLI AN

LE

TRIANGULUM AUSTRALE

C AU OR ST ON RA A LI S

CA P

11

1

des

Hya

20

TRIAN

I IN EM

14

G

13

15

des

Pleia

ARIES

GULU

AN

A

RIG

AU

Algol

DR

0h

M

OM

ED

A ella

Cap

Magnitudes

PERSEUS 5

4

3

2

1

0

brighter

NORTH

The long faint line of stars marking Eridanus the River, ending in Achernar, lies through the zenith. In the south-east, the stars of the Argo con­stel­la­tions (Carina, Puppis and Vela) are return­ing to prom­i­nence, with Canopus in Carina leading the way. The Cross and Pointers have pushed off from the south­ern horizon. The east and north-east are the domain of the hunter Orion, with his dis­tinc­tive belt and sword. His two dogs are fol­low­ ing him up the sky: the Lesser Dog with its bright star Procyon and, further south, the Greater Dog with daz­zling Sirius. Ahead of Orion lies the bull Taurus, notable for the star cluster the Pleiades and the red star Aldebaran as the bull’s eye. Below Orion, the stars of the zodiac sign Gemini con­tinue to rise. The line of the zodiac then runs west­wards and up the sky through Taurus, Aries, Pisces and Aquarius to Capricornus, setting south of west. In the north-west Pegasus moves closer to setting. ­­25

S_Sky_Guide_TEXT_3ed_02.indd 25

7/5/08 11:31:37 AM

Skyview 4 9 pm, January: weeks one and two Sidereal time 0400 SOUTH CIRCINUS

3

Rigel Kent

ARA

r

SA

Hada

S

RU

EN TA U

rux

MUS CA

12h

Ac

VO PA

NA

OCTANS

RI

CA

IN

DU

S

AMA ELE

CH

S

4

A DR HY

APUS

ON

AR TT

IU

TRIANGULUM AUSTRALE

M

CR

C

GI

imo sa

UX

M I C RO SC O PI UM

South Pole

TU

HYDRUS

CA

R

TO

PIC

RETICULUM Ac

IS

M

U EL

SEXTANS

ar

GIU

6

NU

S

PU

LE

HYDRA R

TO UA

EQ

TR

IAN

DR

5

4

3

2

1

0

LU

OR

NC ER CA

M

GE

x

I

IN

or

st

Ca

IGA

M

AUR Algol

AN

Magnitudes

GU

14

llu

S 0h

15

Po

ES

SU

GA

Pleiades

AR

IES

IC

IPT

ECL

A

Hyades

13

IN NI

OC

ER

Pro

OS

cyo

n

SC

M

PI

PE

ION OR an r a b lde

TAURUS

e

us

ge

el

t Be

ON

S

ira

CA

TU

M

SM

CE

Ri

ge

l

S

us

IDA

7

Siri

ER

CANIS MAJOR

FORNAX

COLUMBA

Adhara

CA

IX

WEST 5

EAST

PYX

PIS

rn

M

s pu no a C

OLO

RA

EN

ut

DO

he

HOR

OR

PHO

LPT

alha

AQUARIUS

DO

SCU

Fom

1 PUP

NA

P AU STR ISCIS INU S

S

8

2

A

MENS

S

T AN

LIA

LA VE

ANS

VOL

RU

ICO

G

PR

CA RN U

12

OM

ED

A

PERS

lla

EUS

Cape

brighter

NORTH

In the south­ern sky, two bright stars are prom­in ­ ent: Achernar in Eridanus high in the south-west, and Canopus in Carina well up in the south-east. The Cross and the Pointers remain close to the south-eastern horizon, but are moving up. High up, Fomalhaut in the Southern Fish is heading west. Looking north, Taurus the Bull is well placed, with the Pleiades and Aldebaran unmis­tak­able. The bril­liant con­stel­la­tion of Orion the Hunter is above Taurus and east­wards. Below Taurus, the far north­ern star Capella, in Auriga the Charioteer, is making a brief appear­ance. The Great Square of Pegasus is now setting in the north-west, but the Great and Little Dogs con­tinue to rise in the northeast. There also the bright stars of Gemini the Twins, Castor and Pollux, are now in view. The faint early stars of Cancer the Crab in the north-east mark the east­ern­most of the visible zodiac signs. Running upwards and westwards are five other zodiac con­stel­la­tions, Gemini, Taurus, Aries, Pisces and Aquarius. ­­26

S_Sky_Guide_TEXT_3ed_02.indd 26

7/5/08 11:31:38 AM

Skyview 5 9 pm, January: weeks three and four Sidereal time 0500 SOUTH ARA

US

CIRCIN

3

nt

igel Ke

R

US

CE

osa

Mi m

RU X

Ac

C

M

AEL

12 h

R ATE

A

2

Ac

L VE

AN

PIC

DORADO

LO

8

GI

s

ON

Si

S

RU

EAST s ulu

n yo

N

Pr

Reg

M IS

oc

IN

e CA

CE

PIS

0h

Be

us

ge

tel

TA U

O

R

HYD

M

LEO

BA M

SEXTANS

UM

CAELUM

riu

OR UAT

EQ

RA

ar

LU

PUPPIS OS

7 ER

M

CO

PYXIS

C

rn

RO

p

l

Rige

ira

M

US

CET

US

LEPUS

OC

U

NA

HO

us

AN

6

CAN MA IS JOR

he

RETICULUM

TO R

an o

PI

CA

FORNAX

Adhara

O

MENSA

NS

LA

CR

TU

HYDRUS

VO

SC

NIX

R

IUS

ID

IA TL

RO

South Pole

NA

RI

CA

IC

OCTANS

EON

CHA M

S

PH OE

LPTO

AQUAR

ER

A DR HY

rux

DU

M

APUS

USC A

IN

O PAV

TRIANGUL UM AUSTRALE

r

Ha da

GR US

SCU

ut

alha

Fom

12

WEST

5

NT AU R

4

AU ST PISC RIN IS US

1

PE

S es

IE

16

S

I

MIN

14

UM

GE

AN

r

sto

Ca

DR

x CE

UL

Po

R

des

NG

llu

15

Pleia

IA

13

O

CA N

S SU

GA AR

TR

Aldebaran

Hyad

TIC

LIP

EC

RION

OM

ED

A

IGA

AUR

Algo

l

PER

SEU

Magnitudes 5

4

3

2

1

0

S

Capella

brighter

NORTH

In the north, Orion is nearing the merid­ian, with the bril­liant blue-white Rigel in the lead. Taurus the Bull has passed the merid­ian, and, low on the horizon, Capella shines almost due north. Pisces and Aries are heading for the western horizon, but in the east Orion’s dogs and the stars of Gemini the Twins are rising high. The early stars of Leo the Lion are now rising, with Regulus prom­i­nent. The faint stars of Cancer fill the space between Leo and Gemini. Leo is there­fore the east­ern­most of the visible zodiac signs, fol­lowed by Cancer, Gemini, Taurus, Aries and Pisces. Looking south, the stars of Vela, Puppis and Carina, once parts of the greater con­stel­la­tion of Argo, are high in the southeast. Canopus is leading them up the sky. Behind the Argo stars come those of the Cross and Pointers, still low in the south-east. Achernar is drop­ping down the upper south-western sky, and Fomalhaut is nearing the south-western horizon. ­­27

S_Sky_Guide_TEXT_3ed_02.indd 27

7/5/08 11:31:40 AM

Skyview 6 9 pm, February: weeks one and two Sidereal time 0600 SOUTH ARA

S

PU

S

INU

3

CIRC

r

ad a

S

H

RU

TA U

sa

mo

Mi

EN

C

CA

C

ON

ELE

MA

HYDR

US

9

CHA

NS

he

VOL A

IN A

AR

C

RETICU

LUM

OR

L VE

A

PICT

LIA ANT

LO

DO

G

IU

M

CA

Ca

EL

U

PYXIS

PUPPIS

ra

NS

ha Ad

M

R

TO UA

EQ

S MO

NO

CE

RO

S

7

C M AN AJ IS OR

ar

RO

RA

nop us

rn

HO

DO BA

M

PU

LE Ald

O LE

lus gu

ran

S

IE

AR

es

OR

IN

M

C

ORION

eba

ad

I AN

Re

CES

S

Hy

HY

DR

PIS

n

yo

oc

Pr

Betelgeuse

IC

PT

LI

EC

A

a

l

h

12

EAST

Ac

MENSA LU

CO us Siri

ge

8

SEXTA

NA

South Pole

ERIDANUS

Mir

Ri

VUS COR

TU

FORN AX

CETUS

WEST

6

R

S

PH OE NI X

2

CRATE

RU

OCTANS

CA

MUS

cru x

G

A

RU X

A DR HY

US

APUS TRIANGU LUM AUSTRA LE

t

en

lK

Rig e

IND

PAVO

SC UL PT OR

t

S

5 0h

LU

4

AU ST PI RI SC N IS U S

au

alh

Fo m

12

ARIU

AQU

1

13

Ple

es

AN

I TR

iad

TAU R

I GEMIN

M

LU U

G

14

RS

S

AURIGA

ol

4

3

2

X

LYN

Capella

1

0

N

CA

EU

Alg

5

r

sto

Ca

R CE

15

PE

Magnitudes

16

x

llu

Po

US

brighter

NORTH

In the south­ern sky, bright Canopus in Carina is nearing the merid­ian, as is even brighter Sirius in Canis Major, which is nearly over­head. The Cross is close to nine o’clock, with Achernar almost oppo­site it at around two o’clock. Fomalhaut is setting in the south-west. Looking north, the bril­liance of Orion the Hunter cannot be missed, just west of the merid­ian and high in the sky. Taurus lies below Orion and a little to the west, while further down again is Auriga the Charioteer with Capella not far above the horizon. In the north-west Pisces and Aries are approach­ing their setting. Stretched across the sky to the east of Taurus are the stars of Gemini the Twins (with Procyon in the Little Dog just above), faint Cancer and most of Leo the Lion, notably Regulus. Thus six zodiac signs can be seen, from just rising Leo in the east to soon-to-set Pisces in the west. ­­28

S_Sky_Guide_TEXT_3ed_02.indd 28

7/5/08 11:31:41 AM

Skyview 7 9 pm, February: weeks three and four Sidereal time 0700 SOUTH ARA A

RM

NO

S

PU

LU

GR

US

CIN

nt

Ke

el

Rig

OCTANS

APUS

r

da

Ha S RU U A T EN

US

TRIANG ULUM AUSTR ALE

3

CIR X

CA

South Pole

HY

r

A HY

DR

VOLANS

RET

ICUL

DO

RA

CARINA

LA

US

UM

PICTOR

VE

DO

Ca

IA

no

ANTL

PYXIS

pu

s

Siriu

7

TAN S

Rig

IS CAN R O MAJ

S

RO

el

s

O

N

PISC

O

M

CE

SEX

S

Mira

ra

ha

LEPU

BA

Ad

COLUM

PUPPIS

CA ELU M

US

EAST

rna

MENSA IU M

ERID AN

8 VIRGO

he

US

OG

NAX

CORV

Ac

DR

CHAMAELEON

HO RO L

FOR

OR

UAT

EQ

ES A

ara

12

O

n

h

R

MINO

s

CANIS

ION

RU

S

x

Pollu

GEMINI

14

r

Casto

16

ER

NC

CA

15

PE

RS

R

TA U

O

es

M

ad

O

ei

LE

Pl

LE

ES

I AR

es

OR

lu

eb

e

gu

ad

Ald

on

Procy

us

Re

Hy

ge

DR

tel

13

IC

PT

LI

EC

HY

Be

IN

5

CRATER

NA

SCA

MU

A M im crux os a

CR U

C

TU

P HO EN IX

2 Spica

US

4 UL

CETUS

WEST

6

9

IND

PAVO

SC PT OR

h

0

1

EU

S AURIGA

ella

Magnitudes 5

4

3

2

1

0

LYNX

URS

R

AJO

AM

Cap

brighter

NORTH

Looking south, Canopus has joined Achernar west of the merid­ian. The stars of Carina, Puppis and Vela are nearing the top of the sky. They cover the large area of the sky once allot­ted to the one con­stel­la­tion Argo. The Cross is becom­ing prom­i­nent in the south-east, with the Pointers fol­low­ing it up. Gemini the Twins now lies across the merid­ian, with Castor and Pollux just east of north. Higher up but still east of the merid­ian is the lesser of Orion’s dogs, marked by the bright star Procyon. Orion himself, with the well-known ‘saucepan’ and the bright stars Rigel and Betelgeuse, is high in the north-west sky, along with the Great Dog Sirius marking its heart. East of Gemini, one of the zodiac signs, lie the faint stars of Cancer the Crab, then the brighter stars of Leo the Lion, includ­ ing Regulus, and lastly the early stars of Virgo, now rising due east. At the western end of the visible segment of the zodiac lie some of the stars of Pisces and Aries. ­­29

S_Sky_Guide_TEXT_3ed_02.indd 29

7/5/08 11:31:42 AM

Skyview 8 9 pm, March: weeks one and two Sidereal time 0800 SOUTH INDU

ARA

S

4

PAVO

GR

US

A

OR M

N

TUC

US

IN

Ha

VOLANS

RE

TIC

RA HYD

CARINA IS

XIS

CORVUS

HO

UM

PP

PY

EAST

PU

ANTLIA

Spica

9

LA VE

XT AN

S

VIRGO

UL

RO

LO

G

ra

Adha

IU

M

n

N

SE

CAN

e

CRA TER

ar

MENSA

AU NT CE

R

US

rn

CHAMAELEON

CR A U X M cru im x os a

s

us

A

DR

yon

ge

RA LIB

M

he

pu

OS

Proc

O

ra

Hy

TIC

RI

ba

O

de

Al

LIP

R

USC A

RUS

Ca no

7

ER

EC

ig

HYD

South Pole

R

el

OC

8

HY

17

IS M

ad

INOR

s ulu

g

Re

es

ei Pl

O

TA U

ad

BE COM RE NI A CE S

Ac

3 da r

O

COLUMBA

Rig

ON

tel

t

CT

DO

PI

RA

DO

LU M

LEPUS

C M ANI AJ S OR Si riu s

M

Be

en

1 CA E

ERID ANU S

R

el K

X

Mira UA TO

RC

EN I

S EQ

CI

ANA

OCTANS

PH O

R

FO NA X

CETU

WEST

6

S PU LU

APUS TRIAN GUL AUST UM RALE

0h

SC UL PT OR

5

2

LE

es

RU

S

RS

PE

Pollux

GEM

14

S EU

INI

Castor

16

ER

CANC

12h

15 AU

LEO

RIG

Ca

pe

lla

A

LYNX

4

3

2

1

0

OR

AJ

AM

S UR

Magnitudes 5

OR

MIN

brighter

NORTH

The spec­tac­u­lar Pleiades are about to set in the north-west, with the rest of Taurus the Bull fol­low­ing them down. After only a brief appear­ance, the far north­ern star Capella in Auriga the Charioteer is going down again west of north. Gemini the Twins lies just west of north, with the ‘little dog star’ Procyon higher up the sky. Cancer the Crab and Leo the Lion are pushing through the north-eastern sky, and behind Leo, the next zodiac sign Virgo the Young Maiden is now well in view. Its bright star Spica lies above the eastern horizon. The western and north-western sky still belongs to Orion and his twin dogs. Sirius, the true Dog Star, is well placed to show its bril­liance. Almost due south of Sirius is Canopus, the nearest to it in bright­ness. It stands at one o’clock and is begin­ning its descent of the south-western sky. The Cross, coming up in the south-east, has reached ten o’clock, with the Pointers trail­ing behind. ­­30

S_Sky_Guide_TEXT_3ed_02.indd 30

7/5/08 11:31:44 AM

Skyview 9 9 pm, March: weeks three and four Sidereal time 0900 SOUTH INDUS

4

TUC

ANA

PAVO

0h

A

AR

PH

OCTANS TR I A AU NGUL ST RA UM LE

A

APUS

C

3 ge

LIB

RA

Ri

MU S

SA

LO

RE

TIC

VOLA

sa A CR cru UX x

UL

NS

UM

im

UR TA

US

o

M

CA

A

N CE

RIN

A

HYDR

VELA

se

ES lus

Regu

O

LE

RI

GA

Pollu

x

15

Cast

16

CANCER

INOR

LEO M

12h

Magnitudes 4

3

2

17

or

LYNX

5

TIC LIP

GO

OT

N

eu

lg

te

IO

ran

des

Hya

HYDRA

n

BO

Be

OR

eba

Ald

cyo

CA MI NIS NO R

BE CO RE M NI A CE S

US

SE

S

Pro

VIR

CE

NI

EC

AT E S

AN XT

O

MI

R

TO UA

EQ

R

8

CR

UM

ius

Sir

7

Spica

IA TL

IS

S NI CA JOR MA

CORVUS

PUPPIS

Adhara

PYX

AN

GI

C an op us

C OLU MBA

Rigel

N

EAST

RO

MEN

PI C TO R

M

LEPUS

9

RO

AU

10

H

HO

CHAMAELEON

CA

ad

lK

RUS

D

S PU LU

en t

ar

IX

r

HYD South Pole

INU S

CIR

EN

rna

1

OR AD O

S

EL U

NU

CA

IDA

ER

R TAU

O

GE

P OR SC

NO

O

he

RN

WEST

M

14

S IU

RM

Ac

FO AX

5 6

2

JOR

A MA

URS 1

0

brighter

NORTH

In the north-west, Taurus the Bull is close to setting, with the Pleiades first to go. Higher up and a little to the south, Orion the Hunter and his two Dogs make a spec­tac­u­lar vista as they head for the horizon. In the north­ern sky, Gemini the Twins, with Castor and Pollux, lies west of the merid­ian, and Leo the Lion with Regulus is east of it. Cancer the Crab, devoid of bright stars, lies due north between them. The line of zodiac signs is com­pleted by Virgo the Young Maiden, coming up in the north-east with its bright star Spica, and by Libra the Scales, just rising. To the south, the Pointers, and their home con­stel­la­tion of Centaurus, are pushing the Cross up the sky in the south-east. The stars of the old Argo, now in Vela, Carina and Puppis, are at the top of the sky, with the leading star Canopus, second bright­est in the sky, now past one o’clock. The ‘false cross’, made up of two stars of Vela and two of Carina, is right on the merid­ian. ­­31

S_Sky_Guide_TEXT_3ed_02.indd 31

7/5/08 11:31:45 AM

Skyview 10 9 pm, April: weeks one and two Sidereal time 1000 SOUTH TUCAN

INDUS

A

0

h

4

UM

PH

OE

PI

SC O

TE

NI

X

PAVO

LE

Ach

ern

ar

OCTANS

RA

A US PI OR

MEN

SA

O

US

CI N

es

R

10

An

3

LO

RE

TIC

CHAMAELEON Ha Rig dar MU el SCA Ke nt

VO

S

US

ux

LIBR

A

P LU

RU X

HYDRA

CA

RI

NA

C

VE

LA

CE

LI

PT

IC

SERPENS CAPUT

a A cr

os

IS

COR VUS

PYX

8

s

Siriu

IA

EC

DO

LAN

PUPPIS

ra

Rigel

CANIS MAJOR

Adha

LEPUS

7

9 ANTL

R

TO UA

Spica

RA

UM s

BA

S RU AU NT

DO

UL

pu

LU M

Ca no

CO

im

UM

UM

M

GI

R

AE L

TO

C

S

PI C

NU

tar

CI

RO

E RI DA

WEST

EAST

South Pole

RM

N

HO

RUS

APUS

1

SC

HYD

AX

TR I A N AU GUL ST RA UM LE

RN

A

FO

6

2

EQ

VIR

GO

OS

yo

n

us

A

S

Arc

e

HYDR

tur

us

CA N IN IS OR

M

RU

U TA

14

S TAN

SEX

CR

ER

ge

ION

tel

oc

AT E

R

OC

ON

M

Be

OR

Pr

Regulus

IN

Po

I

llux

Ca

15

sto

OT E BO

EM

S

LEO

G

CAN

r LEO MINOR

I

TIC NA

CA

X

5

4

3

2

URSA MAJOR 1

0

E SV

NE

LYN Magnitudes

17

A M ES CO NIC E R BE

16

CER

12 h

brighter

NORTH

Two new con­stel­la­tions, both zodiac signs, have cleared the eastern horizon. A bright­ish pair of stars marks the first, Libra the Scales. The second is far more spec­tac­u­lar. Scorpius the Scorpion forms a hook of stars, with red Antares among the first to rise. In the south-west, Achernar at the head of the river Eridanus is now well down, with the Cross and the Pointers in con­se­ quence high in the south-east. At the top of the sky and into the south-west lie the Argo con­stel­la­tions of Carina, Puppis and Vela, well marked by the bril­liance of Canopus. Orion is now nearing the western horizon, with the stars of his two dogs higher up the sky. Leo the Lion lies in the middle of the north­ern vista, with Regulus near the merid­ian. Leo is flanked by Virgo in the north-east and Gemini going down in the west. With Taurus now set, Gemini is the west­ern­most of the zodiac signs, with the line then running east through faint Cancer, Leo, Virgo, Libra and newly risen Scorpius. ­­32

S_Sky_Guide_TEXT_3ed_02.indd 32

7/5/08 11:31:46 AM

Skyview 11 9 pm, April: weeks three and four Sidereal time 1100 SOUTH 0

h

INDUS

PH

TUCANA

US RI

TR I A AU NGUL ST RA UM LE

A

A

SA

CHAMAELEON

UM

D

O

O N

CI

res a Ant

CT

O

R

CA

RI

NA

US LUP

UX

S RU TAU

VE

HYDRA

CEN

LA

ica

S RV U CO

A

RG Re

VI

S

RO

n yo S oc NI R CA NO I M

Pr

O

18

gu

lus

EM

G

S

us tu r ER

rc

NC

A

LEO

I

IN

llu

16

x

OT E

O

CR Sp

SERPE NS CAPU T

PI

NS

A

DR

HY TER CRA

BO

RA

D

VO

Mi m os a Acru x Ha Ri dar g e lK en t MUS CA

S

U

N

RC I

10

UL

UM

TLI

AN

LIBRA

GI

LA

RM

PIU

TIC

PYXIS

PUPPIS

EAST

PUS

RE

MEN

South Pole

A

S

SA

A TT GI

AR

3

S PEN SER UDA CA

LO

s

Sirius

OPHIUCHUS

RO

pu Adha ra

CANIS MAJO R CE

NO

se

MO

lgeu

TAN S

TIC

15

A N IS RO AL CO TR S U A

HO

no

Ca

CO LU MB A

Bete

ORION

SEX

EQUA TOR

ECLIP

Ca

OR

US

OCTANS

SC

EL

9 8

CA

Po

SC

HYDR

PAV O

OP IU

LE

r

1

CA UM

LEP US Rigel

WEST

7

TE

NIX

erna

4 M

OE

Ach

E RI D AN U S

6

2

MA CO ICES EN R E B

st

or

17

LEO MIN

OR

LY N

X

TICI ENA

SV

E CAN Magnitudes 5

4

3

2

URSA MAJOR 1

0

12h

brighter

NORTH

Scorpius the Scorpion, with its red star Antares, rides clear of the eastern horizon. In the north-east orange Arcturus marks the posi­tion of Bootes the Bearkeeper, while higher in the sky Spica glows in the hand of Virgo the Virgin. Leo the Lion lies due north, with Regulus prom­i­nent. Gemini now in the north-west is the west­ern­most of the visible zodiac signs, with Cancer, Leo, Virgo, Libra and Scorpius lying suc­ces­sively further east. The great con­stel­la­tion Orion is setting, leaving the western sky dom­i­nated by the stars of the Great and Little Dogs, includ­ ing Sirius and Procyon. In the south­ern sky, the stars of the Argo con­stel­la­tions (Carina, Puppis and Vela) are heading down in the south-west, with Canopus leading the way. Achernar is almost out of sight. The Cross is nearing the top of the sky in the south-east with the stars of the Centaur grouped around. Below the Pointers, three stars form the dis­tinc­tive Southern Triangle. ­­33

S_Sky_Guide_TEXT_3ed_02.indd 33

7/5/08 11:31:48 AM

Skyview 12 9 pm, May: weeks one and two Sidereal time 1200 SOUTH 0h

ERID

PHOENIX DU S

S

rnar

TUCAN A

IN

ANU

Ache

HO

RO

LO

GIU

4

HYDRUS

M

S

1 U RI TA

RE

TIC

M

UL

UM

DO

MENS

RA

A

CO

LE S

TE

South Pole

TR APU IA S AU NGU ST LU RA M LE

CHAMAELE

ON

DO

CT

VO

LA

NS

O

R

no

X

s Antare

CRU LUP

OPHIUCHUS

A

HYDR

A

CA

llu

R

Po

CE N

us

ur

ct Ar

LEO

S

TE

O

BO

18

x

15

16 LEO

LY N

X

OR CANES

AM

2

1

0

brighter

CI

VENATI

AJO

R

Magnitudes 3

17

COMA S ICE BEREN

A N IS RO AL CO RE BO

MIN

URS

4

ES RC

s

HE

NIS CA OR N MI

NI

MI

GE

GO

VIR

UL

A

EQU

SE R CA PENS PU T

DR

n

ROS

cyo

R ATO

Sp

lu

EAST

R TAU CEN

LIBR

NA

US

US

RI

LA

HY

Pro

OCE

ica

TUM SCU

CI

CA

VE ANTLIA

PYXIS

Sirius

MON

S

LIP

EC

S

RVU

CO CRA TER

XT AN

gu

ENS SERP A CAUD

S PIU OR SC

N

RC I

NO

M i m osa Acrux H Rig adar el K e nt MUSCA

US

PU P

ara

PIS

Adh

CAN MA IS JOR

10

TIC

9

SE

Re

A RM

11

us

p

BA

AR A

PI

Ca

NA RO LIS CO TRA S AU

PI U

CO LU M

LE PUS

ORION

WEST

7

3

8

5

T GI SA

OCTANS

M

S

U

N

EL U

CA

PA VO

ER ID A

6

2

12h

URSA

R

MAJO

NORTH

The unmis­tak­able hook of Scorpius, with red Antares in its centre, is climb­ing the eastern sky, and the next zodiac sign, Sagittarius, looking more like a teapot than an archer, has risen in the south-east. The Cross is almost as high as it can get in the south, with the Pointers at ten o’clock. The bright star Canopus is almost at three o’clock in the south-west with the stars of the old Argo con­stel­la­tions, Carina, Puppis and Vela, trail­ing behind. The new stars in the east are a ragged square belong­ing to Ophiuchus, the Man Wrestling with a Serpent. Orange Arcturus in Bootes is prom­i­nent in the north-east, and Virgo is nearing the merid­ian. Leo the Lion now graces the north-west sky, with Regulus prom­i­nent, along with the faint stars of Cancer. Castor and Pollux, the bright stars of Gemini, are departing from view. Above the western horizon, the ‘dog stars’ Sirius and Procyon, both soon to set, remind us of the departed Orion. ­­34

S_Sky_Guide_TEXT_3ed_02.indd 34

7/5/08 11:31:49 AM

Skyview 13 9 pm, May: weeks three and four Sidereal time 1300 SOUTH 0h

Achern

PHOENIX

A

ar

CAN

S

GR U

TU

HO

RO

LOG

IUM

1

CA

EL

DU S

HYDRUS

4

IN

M

CHAMA

U PI O C ES EL T

RA A A RM

no

LA

NS

SC

s

NA

MUSCA

Kent

Acrux

CENTAURU

S

A DR HY

RA LIB

IUCH

R

E AT

CR

Sp

S

OPH

S

AN XT

CANIS R MINO

SE

ica

RVU

US

BA

pu

CRUX

Antares

M

RI

LUPU

EAST

VO

Hadar

S

LU

OR

RA

CO

SE R CA PE PU NS T

gu

Re lu

VIRGO

s

ECLIPTIC

AQUILA

Ca

CA

Rigel

IN

RC

CI

US

IU ORP

M

ELEON

TRIAN AUST GULUM RALE

10

9

15

11

South Pole

APUS

CO

CT

HYD OR

SCUTU

PI ANTLIA

PYXIS

Procyon

UAT

S IU AR ITT G SA

DO

MENSA

PA VO

S

RA

PIS

VE LA

PUP

NO

DO

LUM

OCTAN S

ra

MONOCER OS

WEST

8 EQ

SERPENS CAUDA

ICU

UM ha

s

3

NA RO LIS CO RA ST AU

RET

2

Ad

CA MA NIS JO R Siriu

7

LE

NC CA

O s

ER

turu

Arc

16 N LY

LE

O

X

M

COMA BERENICES

17

IN

OR

CANES VENATICI

18

NA RO LIS CO REA O B

ES

OT

BO

S

LE

CU

R HE

Magnitudes 5

4

3

2

1

0

brighter

12h

URSA MAJOR

NORTH

The sky due north is dom­i­nated by the zodiac sign Virgo with its bright star Spica. Leo the Lion with Regulus is heading for the horizon in the north-west. West of Leo lie the faint stars of Cancer the Crab. Ophiuchus the serpent man is clear of the north-eastern horizon, and another hero, Hercules, sim­i­larly large and faint, is rising further north. To the south, the Cross is now just past the merid­ian. Centaurus is high in the sky, and further east, the Scorpion is rising to prom­i­nence, with the teapot of Sagittarius the Archer close behind. The line of the zodiac runs north-west across the sky from Sagittarius, through Scorpius, Libra, Virgo and Leo, to the soon-to-set Cancer. To the west, Canopus is sinking low. Both Sirius in the Great Dog and Procyon in the Little Dog float above the western horizon, ready to set in an hour or two.

­­35

S_Sky_Guide_TEXT_3ed_02.indd 35

7/5/08 11:31:51 AM

Skyview 14 9 pm, June: weeks one and two Sidereal time 1400 SOUTH Achernar

HOR

h

0

OLOG

HOENIX

P

IUM

1

DO

A

AN

RA

RETIC S

RU

M

G

UM I OP SC O R

US

MENSA

S

OCTA N

VO

IC M

AELEO

PA VO

CA

M U O

PI A AR

N

S

SC

US

CR

UX

Hadar

S RPIU SCO

PU LU

C

IA

S

Antares

RU

EN TA U

SCUTUM

SCA

S

S RIU TA GIT A S

A HY

DR

10 A

CO

US HIU OP

lus

CER

gu

Re

CAN

CH

LI

BR

S

U RV

ica

A

R ATE

CR

S TAN

Sp

SER PE CAU NS DA

BA

NA

MU

Mimosa Rigel x Kent Acru

CIN

CIR

O

RM

A

NA RO S CO RALI T S AU

M

RI

TRIANG U AUSTRA LUM LE

LE

LU

s

NS

N

APUS

TE

CO pu

LA

AM South CH Pole

4

IN D

R

no

ANT L

SEX

9

EAST

TO

Ca

VE LA

PYX IS

R

11

AQUIL

PIC

HYDRUS

PIS

HYDRA

UA TO

U ICORN CAPR

DO

ULU

2

PU P

ROS

WEST

8 EQ

TUC

Ad ha CA ra M NI AJ S OR

7 MONOCE

3

VIRG

S EN RP PUT E S A C

O

ECLIPTIC

O

LE

19

Arcturus

LE

O

16

M

IN

17

CO BER MA ENIC ES

O

R

NA RO S CO EALI R O B

CANE S VENA TIC h

5

4

3

2

12 1

0

URS

LE

U

C ER

H

BOOTES

I

Magnitudes

S

18

A MA

JOR

brighter

NORTH

Most prom­i­nent in the north­ern sky is Bootes the Herdsman, Ploughman or Bearkeeper, depend­ing on which inter­pre­ta­tion of legend is taken. Its leading star Arcturus is close to the merid­ian. In the north-west, Leo the Lion is near to setting, with Regulus showing the way. Above Leo, Virgo is also heading down. Ophiuchus and Hercules hang in the north-east, big but dim. The Pointers have reached the top of the south­ern sky, pushing the Cross into the south-west. The stars of the Centaur lie in the zenith. As a result, Achernar is as low as it can get, hugging the south­ern horizon. Canopus in Carina, with the other old Argo stars, is well down in the south-west. Scorpius and Sagittarius stand high in the south-east, and below them the dimmer zodiac sign Capricornus the Sea-Goat is coming up.

­­36

S_Sky_Guide_TEXT_3ed_02.indd 36

7/5/08 11:31:52 AM

Skyview 15 9 pm, June: weeks three and four Sidereal time 1500 SOUTH 1

DO

RAD

O

PIC

0

h

PH

HOROLOGIUM

Achernar

X

OEN I

RETICULU

M

GR

NS

OCTA

A

S U

OP SC RO IC M

IN

D

4 APUS

PA VO

MU

SCA

S ARIU

A

AR

US

ux

X sa dar imo RU C M

Ha

CIN

CIR A

RM

O

N

S

PU

LU

SCUTU

Anta

M

res

SAG

Acr

Rigel Kent

SCORPIUS

ONA COR ALIS TR S U A

S RIU ITTA

M U PI O C S LE TE

TRIANGULUM AUSTRALE

A

ica

Sp

S

U RV

RA

CO

ER

Regu

UIL

LEO

SA

GIT

O

SE

TA

RP CA ENS UD A

AQ

S U PH

IU

CH

lus

O

CU

LA

SERPENS CAPUT

VU L

PE

rus

16

19 U

RS

A

BE COM RE NI A CE S

M

AJ

O

R

12h

17

NA CORO IS AL BORE

1

0

18 A

R LY a

BOOTES

CA VE NES NA TIC I

S ULE

g Ve

C

HER

URSA

Magnitudes 2

EAST

RIN

ON

YD

H

CRAT

R

TO UA

EQ

ir

CA

AELE

R US

11

Arctu

3

AQU

CHAM

South Pole

CE NT AU

LIP

EC

RA

RG

4

12

ANS

A

10

LIB

VI

5

US

VOL

MENSA

TLI

AN

9

TIC

CAPRICORN

NA

CA

TU

LA

VE

PY

SEXTANS

WEST

HYDRA

8

Alta

s

HYDRUS

US

S U IS IN SC STR I P U A

pu

2

M

R

no

S

IU

TO

Ca

PU PP I

XIS

7

3

MAJO

R

brighter

NORTH

The Cross, though high in the south-west, is now descend­ing. The many stars of the old sign of Argo, now formed into the con­stel­la­tions Vela, Puppis and Carina, crowd the south-west, with Canopus near the horizon. The bright­ish Southern Triangle is about to cross the merid­ian. In the east, Capricornus the Sea-Goat is all but up, so that six zodiac signs span the sky to the north-west where Leo is setting. The signs between (running east to west) are Sagittarius (the ‘teapot’), the bril­liant Scorpius, the dimmer Libra and Virgo high in the north-west. Filling the north­ern sky are Bootes the Herdsman, with its bright star Arcturus well west of the merid­ian, and, further east the heroes Hercules and Ophiuchus, large but with no bright stars. In the north-east, a new bright star has risen, Altair in Aquila the Eagle.

­­37

S_Sky_Guide_TEXT_3ed_02.indd 37

7/5/08 11:31:53 AM

Skyview 16 9 pm, July: weeks one and two Sidereal time 1600 SOUTH M

LOGIU

US HOR O

DAN

ERI

X

0h

t au

S RU G

OCT ANS

VE

LA

MU

APUS

4

SC

CIR TRIANGULUM AUSTRALE

IUM

PA VO

M U PI TE

L

CAP

M

CO ES

ge

A

RM

RIUS ITTA SAG

A

Ri

r

os

a

en

t

US

LUP

s re ta

TUM

An

A

SCU

ULE

US R CA PE U NS DA

LPH

TT A GI

s

SA

16

SERPENS CAPUT

ru

AQ

ctu

UI

LA

LEO

SE

GO

EQU

CH

HIU

OP

US

X

im

DR

VIR

RA

S

lK

U

M

da

NO

CR

rux

US

Ha

AR A

A

Ac

CIN

SCORPIUS

S AQUARIU

N

A

South Pole

HY LIB

Ar

EAST

AELEO

NA

P CO OS ICR

12

CHAM

RIN

S

NA COROALIS USTR

CA

ANS

IS

RU

10

INU

PP

TAU

ca

US

Spi

R

TO UA

EQ

DE

PU

R

VOL

MENSA

CA

TU

S DU IN

F

alh om

PIC

TO

HYDRUS

S R IS INU TO SC R LP PI ST U U A SC

s

CEN

CORV

CRATER

11

air

opu

AN TL IA

8

SEXTANS

IPTIC

ECL

Alt

Can

DO

RETICULUM

NI

OE

PH

DORA

XI S

RA

WEST

9

S RNU RICO

1

nar

Ache r

2

PY

HYD

3

LA

U

EC

12

h

BO

ES

S U

19

N

VU

18

OT

G

17

CY

BE CO RE M NI A CE S

LP

CORONA BOREALIS

A

a

C VE ANE NA S TIC I

4

3

2

R LY

HERC

UR MA SA JOR

Magnitudes 5

ULES

g Ve

1

0

brighter

NORTH

In the north-east, Vega in Lyra the Harp has risen, making a pair with Altair in Aquila the Eagle higher in the east. In the northwest, Bootes with its bright star Arcturus vies with Virgo and Spica. Leo the Lion is setting, with Regulus already gone. Slightly east of north, a large area of sky is taken up with the less than spec­tac­u­lar Hercules and Ophiuchus. To the south, the Cross is now well past the merid­ian and notice­ably lower in the sky, stand­ing at two o’clock. Anticlockwise from the Cross are the Pointers and the fainter Southern Triangle at the top of the sky. Further north the strik­ing Scorpius is almost over­head, with other zodiac signs Sagittarius and Capricornus between it and the eastern horizon. Zodiac signs to the west are Libra, Virgo and the setting Leo. Low in the south-east, two bright stars hug the horizon: the never-setting Achernar in Eridanus, and Fomalhaut in the Southern Fish. ­­38

S_Sky_Guide_TEXT_3ed_02.indd 38

7/5/08 11:31:55 AM

Skyview 17 9 pm, July: weeks three and four Sidereal time 1700 SOUTH M

GIU

OLO

HOR

DORADO

S

NU

IDA

ER

OR

M

CAR

RETICULU

ar

ern

Ach

PICT

1 NS

MENSA US

HYDR

NI X

OE

OR T LP U SC

OCT ANS

C

RU

S

TU

U S CI RIN PIS ST AU

G

S

PAV O

alh Fom

en

t

A

PIU

S

UM UT SC

COR O BOR NA EALIS

BO

LEU

18

UU

HI

IT

TA

NU

S

L VU

LA

CU

PE

17

EQ

ir ta Al

U

AQ

us

20

DE LP

ur

A

IL

SA G

SER PE CAP NS UT

EAST

lK

ct

S EN RP DA SE CAU

PEG

OR

a

RA

GO A M ES CO NIC RE

BE

Ar

AQUA

ORNU

CAPRIC

CORONA AUSTRALIS

RIUS

SC

os

ge

RM

SAGITTA

S

IU COP ROS MIC

EL

T

NO

ES C

im

r

S

LIB

VIR

LEO

OR

UAT

EQ

OPHIUCHUS

12 h

RIUS

M

M

IU

OP

US

Ri

X

M

da

CIN

U

rux

Ha

ARA CIR

CR

Ac

TRIANGULUM AUSTRALE

LUPU

10

S

A

APU

US Spica

11

Antares

S

SC

NT AU R

CORVUS

TIC

ECLIP

ASU

MU

CE

A

DR

S DU IN

0h

South Pole

AN A

4

aut

LA

EON

HY

CRATER

WEST

9

12

VE

CHAMAEL

PH

A

S

INA

VOLA

2

AN TL I

8

3

19 US

GN

CY Vega

OT

ES HERCULES

A LYR

Magnitudes 5

4

3

2

1

0

brighter

DRACO

NORTH

The spec­tac­u­lar Scorpius is now over­head, lying across the Milky Way. Running down to the eastern horizon are three other zodiac signs, the teapot-like Sagittarius the Archer, faint tri­an­gu­lar Capricornus the Sea-Goat, and newly rising Aquarius the Water-Carrier. To the west of Scorpius lie a pair of stars marking Libra the Scales, and Virgo close to setting. In the south-east, the bright star Fomalhaut is prom­i­nent, marking the Southern Fish. In the south-west, the Cross and the Pointers are going down and the stars of the Argo con­stel­la­tions (Carina and Vela) are drop­ping out of sight. Puppis has already gone. In the north-west, the bright star Spica in the setting con­stel­la­tion Virgo is still well up, while further east lies Bootes with its lead star Arcturus. Due north lie the large but faint star signs of Ophiuchus and Hercules. In the north-east, we find Lyra the Harp with Vega and Altair, the bright­est star in Aquila the Eagle. ­­39

S_Sky_Guide_TEXT_3ed_02.indd 39

7/5/08 11:31:56 AM

Skyview 18 9 pm, August: weeks one and two Sidereal time 1800 SOUTH PICTOR

M

ULU

IUM

RETIC

OG

RO L

DORADO

CARINA

VOLANS

1

HO

S

AN U

r

rna

he

Ac

RUS

HYD

CHAMAELEON

IX

A

EN

CA N

South Pole

O PH

TU

MU

SCA

OCT ANS

5 R

US CET h

0

C ECLIPTI

RM

A

11

A

UM

S

LIBR

CAPRICOR

NUS

12

SC

AQ

ATOR

EQU

ur

ct

S

S

us

U

IN

H LP

GA

Ar

MA S CO NICE RE

BE

A TT

GI

SA

SU

ir

ta

Al

PE

NS SERPE CAUDA

UU

LE

US

US

SE R CA PE PU NS T

LA

UI

CH

EQ

HIU

PISCE

UT

OP

EAST

Foma

IU COP ROS MIC

a

O

TEL E SAGITTARIUS

SC lhaut

M

N M

SCO PIU

PIUS

Antares

SCOR

US

LUP

Spica

CORONA AUSTRALIS

UL

S CIS NU PIS STRI AU

ARA

os

CORVU S

VIRGO

10

PTO

S RU G

IN

im

S

RU

R Ke ige nt l

DU

UX

M x

C EN TA U

r LUM TRIANGU LE da US Ha CIN AUSTRA CIR

PAV O

CR

ru

A

S

Ac

DR

APUS

HY

ER

9

AQUARIUS

LA

MENSA

ID

IA

CRAT

WEST

12 h

ER

VE

2

TL

AN

8

4

3

DE A

ECUL

VULP

17 BO

OT

ES

CO BO RON RE A AL IS

20

19

18

US

GN

CY Vega

LYRA

HERCU

LES

b

ne

De

Magnitudes 5

4

3

2

1

0

brighter

DRACO

NORTH

In the north-east, a third bright star has risen, Deneb at the tail of Cygnus the Swan. With Vega in Lyra and Altair in Aquila, it makes up the prom­i­nent Winter Triangle, to be visible for some months. In the west, Virgo with its bright star Spica is prepar­ ing to set and Arcturus in Bootes is close to setting. The large faint con­stel­la­tions Ophiuchus and Hercules fill the sky just west of north. Looking south, the Cross is now at three o’clock in the south-west and going down, with the Pointers and the dis­tinc­tive but only bright­ish Southern Triangle above it. Higher up still, six zodiac signs arch across the sky, from Aquarius in the north-east, through Capricornus and the bright well-placed Sagittarius and Scorpius, on through less showy Libra to Virgo setting in the west. Bright Fomalhaut in the Southern Fish lies almost due east of the Pole. ­­40

S_Sky_Guide_TEXT_3ed_02.indd 40

7/5/08 11:31:57 AM

Skyview 19 9 pm, August: weeks three and four Sidereal time 1900 SOUTH PICTOR

ADO

CARINA

DOR

VOLANS

M

M

MENSA

RO

rn

AX

he

Ac

X NI OE PH

AN A

C

UL

el

ULUM TRIANG ALE AUSTR

SC

S CIS INU PIS STR AU

D

IN

S

A

A

PIUM

ut

IUM

TELESCO

Fomalha

SCOP

NUS ICOR

CETUS

a

U

RM

AR

MICRO

CAPR

AQUARIUS

IN

O

os

r

nt

RC

N

M

da

Ke

CI

US GR

S

U

UX

x

im

Ha

Rig

PAVO

CR

ru

S

OCT ANS TU

12

EAST

Ac APU

TARIU S

ATO R

5

SCA

CORONA AUSTRALIS

SAGIT

FO

I ER

ar

MU

South Pole

S

PIU Antares

VIRGO

10 EQU

RN

DA

CHAMAELEON

US

DR

HY

OR

US

LIBRA

TIC

S U N

1

HO

4

SC

LUP

Spica

WEST

ECLIP

R

LA

N T AU RU S

A

CE

DR

h

COR VUS

9

PTO

VE

2

RET

IU

G

LO

ICU LU

HY

12

3

11

SERPE NS CAUD A

S

air

h

0

Alt

US

HIN

LP

DE

S TE

O

BO

SAGITTA

C BO OR RE ON AL A IS

EQ

A

LE

U

U

S

HU

S

U

LA

I QU

SU

UC

GA

us

tur

Arc

S EN RP UT SE AP C

HI

PE

OP

17

PIS

CES

SCUTUM

ULA

PEC

VUL

18

20

19

Vega

LYRA

HER

CU

LES

US

CYGN

A RT

CE

LA eb

Magnitudes 5

4

3

2

Den

DRAC

O

1

0

brighter

NORTH

The north­ern sky is dom­in ­ ated by the three bright stars of the Winter Triangle, Vega in Lyra the Harp almost due north, Deneb in Cygnus the Swan a little to the east, and Altair in Aquila the Eagle high in the sky. The rest of the north is dull by com­par­i­ son; Aquarius and the rising Pegasus in the north-east, the large but dim Ophiuchus and Hercules in the north-west, and Virgo and Bootes setting in the west and north-west. The Cross is well down in the south-west, with the Pointers above it. Higher still, curved Scorpius is past the merid­ian. Libra and Sagittarius, both zodiac signs, lie west and east respec­tively of Scorpius. The west­ern­most sign is the setting Virgo, while Capricornus and Aquarius lie north-east of Sagittarius. The latter are out­shone by Fomalhaut in the Southern Fish, which is now prom­i­nent in the south-east.

­­41

S_Sky_Guide_TEXT_3ed_02.indd 41

7/5/08 11:31:59 AM

Skyview 20 9 pm, September: weeks one and two Sidereal time 2000 SOUTH CARINA

s

opu

Can

RA

DO

UM

UL

TIC

MENSA

1

A ID ER

HY

A

X NI OE PH

S RU G

TEL

SCU

CETUS

im

a

da

Ke

nt

CI

r

RC

IN

U

S

AR

A

OPI

UM

INDUS

G

AQUA

RIUS

el

M

os

Ha

PAVO

ESC

Fomalhaut

Rig

S

IS PISC INUS TR AUS

5

EAST

NS

MICROSCOPIUM

S NU IDA

AX RN FO

OCTA

APU

AN

OR LPT

rux

M GULU TRIAN TRALE AUS TU C

UX

Ac

r

na

Ac h

CR

CHAMAELEON South Pole

er

ER

MUS

CA

US

DR

12

SA IT

SC

11

RI

TA S

U

UM

UT

R

S NU

RE

PIUS

CO AUS RONA TRA LIS

SCOR

Antare s

UA TO

H

3 NO RM A

LU PU S

LIBRA

VIRGO

WEST

10 EQ

UM

LA

S

IC

GI

DO

RU

A IPT

LO

VE

2 VOLANS

CE N TA U

DR ECL

OR O

OR

PICT

12h

HY

9

4

UC

HI

PISC

OP SE R CA PENS UD A

S

HU

S EN RP SE PUT CA

ES

CAPRICORNUS

S

EU

AQUILA

UL

U EQ

NA RO IS CO EAL R BO

13 G

AN DR

PE

DELP

A

S

HINU

TA

OM ED

SAGIT

AS

U

S

Altair

VULPECULA

18

HE

RC

19

UL

20 0h

ES

LYRA Vega

Deneb

Magnitudes 5

4

3

2

A ERT

LAC

CYGNUS 1

0

brighter

NORTH

The south­ern sky has its duller spring-time look. The bright stars of the Cross and Pointers are sinking in the south-west, Canopus in Carina is against the south­ern horizon, and Achernar in Eridanus is still coming up in the south-east. Of the brighter stars only Fomalhaut in the Southern Fish is high, lying in the south-east and forming a dis­tinc­tive pattern with some stars of nearby Grus the Crane. Scorpius is plung­ing head-first into the west, with Libra the Scales leading it down and Sagittarius the Archer close behind. Further east are other fainter zodiac signs Capricornus and Aquarius. Due north glitter the stars of the Winter Triangle: Altair in Aquila the Eagle, Vega in Lyra the Harp and Deneb in Cygnus the Swan. No other bright stars are in sight, but the Great Square of Pegasus, only bright­ish but dis­tinc­tive, has risen above the north-east horizon, with the early stars of Pisces the Fish following it up the sky. ­­42

S_Sky_Guide_TEXT_3ed_02.indd 42

7/5/08 11:32:00 AM

Skyview 21 9 pm, September: weeks three and four Sidereal time 2100 SOUTH A

CARIN

s

pu

ano

C

2 R

TO

PIC

12 h

VOLANS CR

UX

O

RA D

M

EL U

CA

DO

M

RO

UM

UL

IC

HO

RE T

Acr

A

MENS

IU

LO G

MUS

CA

CHAMAELEON RU S

1

el

CIR

CIN

N

sa

U TA

RU

S

da

r

Ke

US

nt

6

OCTANS

CE

mo

Ha

Rig

South Pole

D

HY

Mi

ux

3

A

DR

HY

APU

S

rn

FOR

R

S RIU UA

R

O UAT

EQ

AQ

RN

US

ECLIPTIC

GIT

US

EQUULE

13

US

DELPHINUS

TA

IES

S PIS

CE

ILA

ir

AR

S EN A RP D SE AU C

AQU Alta

SA

EAST

SCU

ut alha Fom ISCIS P US TRIN AUS

M

TUM

S PEN SER UT CAP

ICO

Mira

OP

IU

MICROSCOPIUM

LPTO

SC

G

OE PH

LE

SCU

PR

S ANU

A ID ER

NIX

S RU

TE

US

IND

SAGITTARIUS

CO AU RONA STR ALIS

S

5

CETUS

PAVO

A

AN

TUC

A

SCO RPI U

US

IUCH

OPH

CA

ERID

A

A

AR

RM

Ant ares

LIBRA

12

11

NAX

UM E UL AL NG TR IA US TR A

NO

S NU

ch e

S

PU

LU

ar

9

WEST

10

4

AS

G PE

VULPEC

18

ULA

19

HE

RC

U

LE

S

20 A

LY R

A

Veg a

ED

M

O DR

AN

CYGN

US

0h

Deneb

Magnitudes 5

4

3

2

1

0

A ERT

LAC

brighter

NORTH

In the north-west Ophiuchus and Hercules are setting. The Winter Triangle of Vega, Altair and Deneb dom­i­nates the north-west, with the fainter Great Square of Pegasus in the north-east. Further east still, all of the faint stars of the zodiac sign Pisces the Fish are now in view. With the sur­round­ing con­stel­la­tions such as Aquarius and Cetus the Whale (just rising), Pisces makes up the ‘wet corner’ of the sky. In the south, the Cross is low to the south-west. Achernar, the end of the river Eridanus, is cor­re­spond­ingly high in the south-east. Higher still is Fomalhaut, the mouth of the Southern Fish. In the west, Libra is close to setting and Scorpius is diving down­wards, claws first. The line of the zodiac then runs east­wards through Sagittarius, Capricornus and Aquarius to the newly risen Pisces.

­­43

S_Sky_Guide_TEXT_3ed_02.indd 43

7/5/08 11:32:02 AM

Skyview 22 9 pm, October: weeks one and two Sidereal time 2200 SOUTH VELA 12

h

INA

CAR

2 S

VOL AN

PU

PIC

no

BA

Ca

CHAMAELEON

DO

M LU

UM

UL

S

US

AR

DR

HO

RO

HY

A

S NU

r

he

IDA

Ac

na r

A

TUCAN

VO PA

ER M

IC

RO

SC

O

PI

U

M ITTA

SAG

OR

IC

PR

US

CA

RIUS

R ATO

EQU

AQUARI

US

S

NU

IES

SUS

PEGA

LA

13

TR IA

N

20

LY R

A

CY

GN

US TA LACER

Dene

b

Magnitudes 4

3

2

DA

ME

RO

D AN

a

5

LU

M

CU

U

LPE

19

S

US

G

VU

NU

AR

PHI

PI

ULE

DEL

TT A

SC

EQU

ir

GI

ES

UL

A

IL

RC

U

HE

AQ

ta

SA

ECLIPTIC

ES

S EN RP A SE AUD C Al

Ve g

EAST

FORN

R SCULPTO

S

RU

G

Fomalhaut PISCIS S AUSTRINU

PHO

EN

AX

IX

INDUS

IS

M

12

TAUR

US

COR AUS ONA TRA L

SCUTU

CETUS

IN

OCTAN

M

IUS

PI U

OR P

S

18

6

RC

S

IU G

CI

APU

M

E CA

South Pole

1

LO

S

ent el K dar Ha

LUM NGU ALE TRIA USTR A

MENSA

TIC

RE

RU

sa

Rig

RA

DO

ux

A

AU NT

mo

Acr

MUSC

TO R

pu s

Mi

T E LE SC O

SC

tar es

An

OPHIUCHU

WEST

11

5

Mira

CE

N OR M A

RA

10

M LU CO

CRU

X

S

PP I

3

LU PU S

LIB

4

0h 1

0

brighter

NORTH

On the south-east horizon, Canopus, second bright­est star in the sky, is making a return, bal­anc­ing the sinking of the Cross and the Pointers which are now at four or five o’clock. Higher in the south-east sky, Achernar marks the end of the river Eridanus. Fomalhaut in the Southern Fish nears the top of the sky. In the north-west, the Winter Triangle of Altair (in Aquilia the Eagle), Vega (in Lyra the Harp) and Deneb (in Cygnus the Swan) remains prom­i­nent. The north-east sky belongs to the Great Square of Pegasus, rep­re­sent­ing both Pegasus and Andromeda. Further east, the zodiac sign of Aries the Ram has risen. The faint sign Pisces lies mostly above Pegasus, while further west are Aquarius and Capricornus. Sagittarius and Scorpius con­tinue their fall down the western sky.

­­44

S_Sky_Guide_TEXT_3ed_02.indd 44

7/5/08 11:32:03 AM

Skyview 23 9 pm, October: weeks three and four Sidereal time 2300 SOUTH 12

h

A

VEL

CENTAURUS

CRU

X

Mim

INA

CAR

PIS

UP

P

osa

Acru

OL A

Rig

SA

no

AD O

R

M LU

TUCANA

VO PA

NIX OE

ERIDANUS

PH

SCULPTOR

PISCIS AUSTRINUS

IUM

COP

US

Fomalhaut

CET

CO

PRI RN

S PEN SER DA CAU

US

U

AR

EAST

S

GRU

ROS

MIC

CA

5

12 AQ

Rigel

LEPU

r

rna

he

Ac

S

E CA

A

DU S

IN

NAX

A

AR

NS

UM

FOR

RM

CO PI C AU ORON STR A ALI S SAGITTARIUS

SCUTUM

OPHIUCHUS

WEST

11

6

R

TO UA

EQ

Mira

O

US

OCTA

S

HYDRU

N

IN

S

ES

EL

T

1

M IU G LO RO HO

UM

UL

IC

RE T

RC

APU

South Pole

res

IU S

DO

CI

SC OR P

An ta

L CO

BA UM

Ca

ent

LUM NGU E TRIA USTRAL A

PIC

MEN

S

el K

CHAMAELEON

TO R

RU

ar

A

pu s

AU NT

Had

MUSCA

NS

V

CE

x

2

3

LU PU S

LI BR

10

4

IU

Al ta

SA

LA

UI

ir

UU

A TT

GI

LP

HI

NU

S

ECLIPTIC

S

CE

LE

US

14

S PI PEGASUS

AR IE S

AQ

EQ DE

TA U

RU

S

S

VU

LP

EC

19

UL

A

13

20

LY R

UM

UL

A

CY

I

GN

TR

US

5

4

3

2

LACERTA

Den

1

0

EDA

ROM

AND

eb

Magnitudes

G AN

12h

brighter

NORTH

In the north-west, the Winter Triangle has begun to set, with Vega in Lyra the Harp first to go. Deneb in Cygnus the Swan will be next, leaving Altair in Aquila the Eagle higher in the sky. In the north, the Great Square of Pegasus is about to cross the merid­ian. Aries the Ram in the north-east, with a dis­tinc­tive pair of bright­ish stars, is the east­ern­most of the risen zodiac signs. Further west, and running steeply up the sky, lie Pisces, Aquarius, Capricornus and the ‘tea-pot’ Sagittarius. In the west, Scorpius is setting. The ‘wet corner’ of the sky is over­head, stretch­ing both north-east and north-west. Constellations such as the Southern Fish, Aquarius, Capricornus, Cetus, Eridanus and Pisces all have watery con­nec­tions.

­­45

S_Sky_Guide_TEXT_3ed_02.indd 45

7/5/08 11:32:04 AM

Skyview 24 9 pm, November: weeks one and two Sidereal time 2400 SOUTH 12h

CENTAURUS

CEN

RU TAU

CRUX Mimosa Acrux

LA

VE

Rigel

Kent

MUSCA

R

CA

S

LAN

VO

PU

A

NSA

AR APU

South Pole

OCTA

NS

RA

LU CO

r

rna

Ach e

R

S

A

HO

LEPU

VO PA

TUCAN

DU S

IN

US GR

MI CR

ENIX

O ut

Rigel

5 R ATO EQU

IU

Mi

ra

R UA AQ S

S TU

S

ha

TAU RU

SCU

al

ERIDANUS

FORNAX

IS PISC US RIN AUST

S

S SERPEN CAUDA

U ICORN

CAPR

Fo m

12

6

LPT OR

M

PHO

SC OP IU

SAG IT TA RIUS

M ELU CA

M IU OG OL

s Siriu

UL UM

DO

A MB

HYDRUS

TIC

RE

DO

NIS CA OR J MA

n Ca

h Ad

u op

s

ME

A

S LE

TE SC OP IU M CO AU RON STR A ALI S

SCUTUM

OPHIUCHUS

WEST

11

EAST

RM

US

S

1

ORION

CIN

ELEON

CHAMA

TO R

PIC

7

NO

PIU

ara

US

CIR

ULUM TRIANG LE A AUSTR

S

PP I

P LU

2

INA

S

Hadar

3

SC OR

10 OPH IUCH US

4

Ald eb

EQ

ir

a Alt

ILA

aran

U AQ

CE

es

US PEG

Hy ad

LE

UU ECLIPTIC

ASU

S

S

IES

AR

Ple iad es

A TT GI SA

LA

NU

CU

HI

LP

LPE

DE

VU

ES

PISC

19

14

13

20

UM UL

NG

IA TR

CY GN

US

S

EU

RS

PE

l

EDA

LACER

OM NDR

o Alg

A

TA

Magnitudes 5

4

3

2

1

0

brighter

0h

NORTH

In the east, the rising of Rigel signals the return of the bril­liant con­stel­la­tion Orion the Hunter, announcing that summer is coming. To the north-east, reddish Aldebaran has joined the Pleiades marking Taurus the Bull. Though fainter, the Great Square of Pegasus is prom­i­nent, strad­dling the merid­ian. In the north-west, Cygnus is setting, taking Deneb, and Aquila with its bright star Altair is headed the same way. In the south-west, Scorpius is setting, and the visible zodiac signs run from Sagittarius in the west, through Capricornus, Aquarius and Pisces, to Aries and Taurus in the north-east. The Cross is upside-down against the south­ern horizon, but Canopus in Carina and Achernar in Eridanus (in the south-east) and Fomalhaut in the Southern Fish (over­head) are prom­i­nent. The latter makes a lop-sided cross with stars of Grus the Crane.

­­46

S_Sky_Guide_TEXT_3ed_02.indd 46

7/5/08 11:32:06 AM

THE NIGHT SKY IN DETAIL

Using the Sky Charts The 20 charts in this section cover the whole night sky visible from around 35 degrees south lat­it­ude in much greater detail than the Skyviews in the pre­vi­ous section. Each chart is accom­pa­nied by infor­ma­tion about the celes­tial objects visible in the par­tic­u­lar region of the night sky and about the stories behind the stars and con­stel­la­tions. To deter­mine which of the Sky Charts to use, refer to the large numbers dis­trib­uted across the Skyviews. For instance, on the Skyview for 9 pm in early June (No. 14), the region near Leo the Lion (in the north-western sky) bears the number 16, indi­cat­ing that Sky Chart 16 shows this region in greater detail. There are three groups of charts in this section.

Charts 1 to 4

Charts 5 to 12 •  These charts are to be read looking to the north. •  The sky areas covered by these charts are above the horizon for about 14 hours at a stretch. •  The stars shown on these charts will be found in a band running from east to west and cross­ing the sky high up to the north of the zenith.

Charts 13 to 20 •  These charts are to be read looking to the north. •  The sky areas covered by these charts are above the horizon for around 8 to 10 hours at a stretch. •  The stars shown on these charts will be found in a band running from north-east to north-west and cross­ing the lower half of the north­ern sky.

•  Most of the sky area covered by these charts is always above the horizon. •  These charts are to be read looking to the south.

­­47

S_Sky_Guide_TEXT_3ed_03.indd 47

7/5/08 11:32:52 AM

Chart 1 0 Hours to 6 Hours RA 90 to 45 degrees Dec

This is a crowded corner of the sky in terms of con­stel­la­tions, though none of the stars is bright other than Achernar. This first mag­ni­tude star, ninth in order of bright­ness among the stars, marks the end of the long winding con­stel­la­tion Eridanus the River. This weaving line of faint­ish stars (only Achernar is brighter than mag­ni­tude 3) is the longest of the con­stel­la­tions, and begins way to the north near Orion. Eridanus is most likely a hea­venly rep­re­sen­ta­tion of the Nile. It is far enough north to have been seen (and named) from Egypt in ancient times. Grouped about Eridanus and mostly further south are a host of minor star pic­tures named much more recently; a couple of birds (a toucan and a phoenix), a male water serpent (Hydrus), a sword­fish (Dorado), the ‘table mountain’ (Mensa) and four very dull ones: Pictor (the painter’s easel), Caelum (the engrav­ing tool!), Horologium (the clock) and Reticulum (the reticle, a grid used for making star maps). Of these, the most inter­est­ing is perhaps Phoenix, with a roughly ‘Australia-shaped’ col­lec­tion of bright­ish to medio­cre stars lying clock­wise of Eridanus. Of far greater inter­est are the two Clouds of Magellan, named after the great Spanish nav­i­ga­tor but not dis­cov­ered by him. They were seen by the first Portuguese sailors to round the Cape of Good Hope some decades earlier and were known for a time as the Cape Clouds. These two misty patches of light are visible to the naked eye only in a clear dark sky. Both are com­posed, like the Milky Way, of vast numbers of sep­ar­ate stars, as a look through binoc­u­lars will reveal, but lie beyond the Milky Way, being the nearest star systems or gal­ax­ies to our own. In the sky they lie roughly equi­ dis­tant from each other and from the South (Celestial) Pole. The Large Magellanic Cloud (LMC) lies mostly in the con­stel­la­tion Dorado, tucked on the clock­wise side of the tri­an­gle of stars that covers most of Hydrus. It is about 10 degrees square, the width of a fist at arm’s length in each direc­tion (or 20 times the width of the Full Moon). Binoculars will clarify its shape, and should reveal within the Cloud the spider-like Tarantula Nebula (N2070), also called the Great Looped Nebula, which is about the size of the Full Moon. The nebula sur­rounds a star called 30 Doradus. It was near to this nebula that the super­nova known as 1987A appeared in February 1987. The Small Magellanic Cloud (SMC), which lies in Tucana, is only one sixth the appar­ent size of its neigh­bour, and further away (200,000 light years rather than 160,000), but seems brighter. Two degrees (a thumb’s width) clock­wise from the SMC lies one of the finest glob­u­lar clus­ters in the heavens, bet­tered only by Omega Centauri. This is 47 Tucanae (N104), spec­tac­u­lar in binoc­u­lars or smaller tele­scopes and aston­ish­ing in bigger ones. A smaller glob­u­lar cluster (N362) abuts the SMC on the side away from the pole. A double star worth seeking is Herschel 3670 in the con­stel­la­tion Reticulum (near 4 hr 30, 63 deg.). A pair of stars (mag­ni­tudes 5.9, 8.4) are sep­ar­ated by a large­ish 32 seconds of arc. The colour contrast is strong, com­monly seen as yellow and blue. In Pictor lies Dunlop 18 (Iota Pictoris); a pair of yellow stars (mag­ni­tudes 5.6 and 6.4) sep­ar­ated by 12 arc seconds (near 4 hr 50, 54 deg.). Horologium boasts a notable Mira-type var­i­able. R Hor lies close to the border with Eridanus (near 3 hr, 50 deg.) and varies from mag­ni­tude 4.3 to 14.3 every 404 days.

­­48

S_Sky_Guide_TEXT_3ed_03.indd 48

7/5/08 11:32:52 AM

3 P

–80°

M

APUS D

P

CHAMAELEON

H

I K

R W

2

–70°

H RS

Q

C

S

Q

R

TZ

X

T

N

U

B X

E N

I

M

E

2070 Tarantula SN1987A Nebula

H

B

T

S

L N

HYDRUS

47 Tuc (104)

Q 362

–70°

L

L

P

H

Z

D P

Z B G

H

K

N

B

H

K

Z

COLUMBA

1672

A

I

H H

18

A

E

1851

L

1808

R

1566

K Z

G

G

RETICULUM

A

D

E

TUCANA

R

CAELUM

Z

H

B

D

L

A

HOROLOGIUM

I

B 

q1

X

q2

Z

Z

P

1291

ERIDANUS

C

–50°

L

L

T Q

A

J

0h

SCULPTOR 300

1h

MAGNITUDES

4

A

1097

G I

M

X L

1360

B

W

L

U

5

FORNAX

I

Ankaa

55

6

L

L

U

J

P

P

5

–30°

S

1398

H

J

PHOENIX

4h

T

G

K I

Q

I

C

R

D

Acamar

E

I Q

Y

N

M

GRUS

–40°

B

1399

1365 1316

H H

S

i

h

K

D

R

–30°

g

e

s

K

f

y

R

I

J

p

W

H G

41

H

Achernar

A

6

43

1433

Z

–60°

5h

B

M A

4

6h

Q

Z

R

H

PICTOR

K

DI

1313

E P

G

B

G

B

SMC

R

G

h 3670

K

Q

PUPPIS P P

L

Q

G

D

DORADO

Q

A

D

WZ

N

N

Y

N

Canopus

Q

LMC

G

B

INDUS

L

G

N

H H

N

M T

Y

I

MENSA

G G

G

P

A

CARINA

M

P

D

OCTANS

L

–80°

K

P

–40°

T

O

A

VOLANS

I

Z South Celestial Pole

–90°

–50° A

G

E

Z

–60°

D

Z

T

Z

T

G

–20° 1232

T

N

ERIDANUS

2h

3h

–20°

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­49

S_Sky_Guide_TEXT_3ed_03.indd 49

7/5/08 11:32:54 AM

Chart 2 6 Hours to 12 Hours RA 90 to 45 degrees Dec

This part of the sky was once ruled by the mighty con­stel­la­tion Argo Navis, the ship Argo. In the Argo the ancient Greek hero Jason and his band of 50 ‘argonauts’ rowed and sailed west­ward into the Black Sea in quest of the magical Golden Fleece in the century before the Trojan War. The ram from which the fleece came is rep­re­sented else­where in the sky by the zodiac sign Aries. Perhaps because it took up so much of the sky, Argo is broken down into four con­stel­la­tions on modern maps; the roughly rec­tan­gu­lar Carina the Keel, the mis­sha­pen pen­ta­gon of Vela the Sail, another rec­tan­gle of stars marking Puppis the Poop, and Pyxis the Mariner’s Compass, which is hard to find. The stars of Puppis and Pyxis lie further away from the South Pole than the other two con­stel­la­tions, and not all of them are marked on this chart (see Chart 7). Two stars of Vela and two of Carina are com­monly grouped to form the False Cross, larger and fainter than the ‘real’ Southern Cross, which lies 40 degrees anti-clockwise, but oriented sim­i­larly in the sky. Canopus, the bright­est star in the area and the second bright­est in the whole night sky, lies in Carina. Many maps show it as marking nothing more impor­tant than the end of one of the oars, though more ancient sources place it on the rudder. One expla­na­tion of the name is that it is from a famous sea captain at the time of the Trojan War, when he com­manded the ship of King Menaleus. Canopus is a guide to the notable semi-regular var­i­able star L2 Puppis, which lies 10 degrees anti-clockwise and a similar dis­tance further away from the pole. L2 Pup shifts from mag­ni­tude 2.6 to 6.2 (that is, from visible to invis­ible with the naked eye) every 141 days. Two notable Mira-type var­i­ables inhabit Carina, both found close to the 10 hours RA merid­ian. R Carinae (near 9 hr 30, 63 deg.) moves from 3.9 to 10.5 and back every 309 days; S Carinae (near 10 hr 09, 61 deg.) moves between 4.5 and 9.9 every 149 days. Vela con­tains a pair of doubles (four stars alto­gether), close enough to be in the same field of view (near 10 hr 45, 49 deg.); Herschel (h) 4330 has a yellow 5.1 mag­ni­tude primary with a blue 8.6 mag­ni­tude com­pan­ion 40 arc seconds distant; Herschel (h) 4332 is blue and white, mag­ni­tudes 7.2, 9.6, sep­ar­a­tion 28 arc seconds. Also within Vela, and occu­py­ing the most clock­wise posi­tion among the bright­ish stars in that con­stel­la­tion, Gamma Velorum is a rel­ a­tively easy double; blue-white stars of mag­ni­tude 1.8 and 4.3, sep­ar­ated by 41 seconds of arc. The Milky Way flows across this region of sky, delin­eat­ing one of the spiral arms of the galaxy in which we live. Against the Milky Way, binoc­u­lars will reveal some of the bright and dark intri­ca­cies of the Eta Carinae Nebula ­(N3372), clock­wise from the Southern Cross about 30 degrees (about one hour on an ordi­nary clockface) and there­ fore about 101 ⁄ 2 hours of RA. At mag­ni­tude 3 and 2 degrees diam­e­ter (four times the diam­e­ter of the Full Moon), the nebula is a naked-eye object on dark nights. Several bright star clus­ters sur­round it. The star Eta Carinae lies at the heart of the nebula, and is one of the largest, most lumi­nous and most unstable stars known. Now at seventh mag­ni­tude, it is visible only with optical aid, but last century it out­shone all but Sirius. It is often thought the star most likely to form the next super­nova visible from Earth. The fading of Eta Carinae has dimmed the out­lines of the Keyhole Nebula, as the Eta Carinae Nebula was called by John Herschel. Five degrees pole­wards from Eta Carina is the bright open cluster I2602 (also called Theta Carinae), mag­ni­tude 2 and nearly a degree across. It con­tains about 30 blue-white stars. Only 650 light years away, it is one of the closer clus­ ters. Another cluster (N3766, known as the Pearl Cluster) lies 10 degrees clock­wise of Alpha Crux (or roughly halfway between Alpha Crux and I2602). It is large (75 minutes by 50 minutes) but faint (mag­ni­tude 7). You might also chase I2391 (Omicron Velorum, mag­ni­tude 2.5, diam­e­ter 50), which lies about 10 degrees pole­wards and anti-clockwise of Gamma Velorum.

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S_Sky_Guide_TEXT_3ed_03.indd 50

7/5/08 11:32:54 AM

4

–80° R W

L C U

S T

P

P

–90°

K

I

Z

P I

MENSA

Q

G

E D

K

P P N

A

m

c D1

e1

E

2516

M

L

D

2547

V

Canopus MY

Q

T

Q

H

G

L2

COLUMBA

H

P

P

D

N

Naos

M

a

T

y

F

1851

x

6

7

h

MAGNITUDES

6

5

4

Q

d1-3

L Q

B A

G

r w

G

Z

K

D

HYDRA –20°

2451 e

v2

MZ

H

f

v1 2527

2439 h

 Z Z

E

q

2477

c

z

P

k2

PYXIS

h1 2546

Z

b

PUPPIS E

k1

h

h2

S

A



2997

l

S

C

N

d

e

10h

E

O P

L1

g w

I

Y

a b

A

B

ANTLIA

L

f

n

–30°

Y

z

AH

B

PICTOR

H c

D

G

J

N

8

y

C

A

A

Z

u

VELA

I.2395

Q

3132

K

F I.2391 E

O

q

m

M

C

G

K

–40°

I

O

N

H H

r

K

A

CARINA

11h

U

3201

D

–60°

I

s

Q

O

f

e2

B

–50°

N

g

b1,2

d

Avior

R

J

2867

a

C D2

i

t h

Aspidiske I

B

L

M

Y

J

p

i

B

H

x

k

VOLANS H

R

2808

E

r I.2581

3144

l

n

z

3293

S

C1

u

H

t1 t2 s

q

U

B

D

WZ

Z

w

C3 C2

P

3532

3372

p

Miaplacides

Q

G

I

2070 Tarantula Nebula

DORADO G

E I.2448

Z

B SN1987A

1

A

A

z2

Eta Carinae U Nebula

Q

L

12h

B

O 

T

M

D

E

3918

z1

W

u

CENTAURUS D

K

l

S

R

CRUX

Q 

I.2602

H

L

Q

H

3766 I

G T

F

D

n

w

G

E

M L

H

G

A

Z

L

H

A

LMC

MUSCA

Z

3211

H

–70°

E

G

Q

E

Z

S

–40° e

Acrux

Z N

RS

4609

B

D

D

M

G

–50° H

M

L K Mimosa I B G Gacrux

Q

4833 R

4372

P

Z

K

D

K

E

X

D

I

–60° 4755

A

B

TZ

N

I

H

CHAMAELEON

3195

M

S

H

R

HYI

E

H

I

OCTANS

–80°

Q

D

South Celestial Pole

3

–70°

APUS

7

–30°

8

9h

–20°

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

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S_Sky_Guide_TEXT_3ed_03.indd 51

7/5/08 11:32:57 AM

Chart 3 12 Hours to 18 Hours RA 90 to 40 degrees Dec

The stars of Crux Australis, the Southern Cross, are well known from their pres­ence on the Australian and New Zealand national flags, though it has been sug­gested that the con­stel­la­tion, which is the small­est in the sky, resem­bles more a badly made kite than a cross! Crux, the small­est of the offi­cial con­stel­la­tions, was formed out of stars of Centaurus by early nav­i­ga­tors of the South Seas, and was offi­cially entered on the charts in the six­teenth century. The five main stars in Crux decrease in bright­ness moving clock­wise around the con­stel­la­tion, begin­ning with Acrux at the bottom. Beta Crucis is often called Mimosa (a name for wattle). Gamma Crucis at the top is dis­tinctly reddish, even with the naked eye, being a red giant star. The fifth star, Epsilon Crucis, is on the lower right when the Cross is upright. Acrux is a multi­ple star; the two main com­po­nents being blue-white, mag­ni­tudes 1.5 and 5, lying 90 arc seconds apart. The brighter star is itself double, but the com­po­nents are only 4 arc seconds apart and dif­fic­ ult to sep­ar­ate in small instru­ments. Five degrees anti-­clockwise from Gamma Crucis, Mu Crucis is an easy double in binoc­u­lars: two white stars, 35 arc seconds apart, mag­ni­tudes 4.3, 5.5. Trailing the Cross in its journey around the south­ern sky, and showing the way to it, are the two Pointers. More for­mally, the stars are known as Rigil Kentaurus and Hadar (or Agena), or Alpha and Beta Centauri, being the two bright­est stars in the con­stel­la­tion of Centaurus the Centaur which sur­rounds the Cross on three sides. Centaurs were myth­i­cal beasts, half man and half horse and often held to be wise and noble. The con­stel­la­tion may rep­re­sent the centaur Chiron, under whom the hero Jason was edu­cated. The Pointers look about equally bright but are in reality very dif­fer­ent, Beta being 100 times further way than Alpha and emit­ting 10,000 times more light. Alpha is not only the nearest bright star to our Sun, it is also the most Sun-like of the nearby stars, with a very similar abso­lute mag­ni­tude and surface tem­per­a­ture (though about twice the mass and four times the intrin­sic bright­ness). Alpha is a multi­ple; its bright com­po­nents are white stars (mag­ni­tudes 1.0 and 1.4) lying 21 seconds apart. The third star in the system, Proxima Centauri, is a dim red dwarf, hard to find at mag­ ni­tude 11, and lying 2 degrees away from the primary. It is cur­rently the nearest star to the Sun. On the old star charts, the Centaur stands astride the Cross, facing anti-clockwise. The Pointers mark his forelegs and two stars to the upper right of the Cross (when upright), and one imme­di­ately clock­wise from it, locate his hin­dlegs. Stars rep­re­sent­ing his upper body lie further away from the Pole and anti-clockwise. In the Centaur’s hand is a spear with which he is dealing with a wolf (Lupus). Polewards of the Cross we find the small con­stel­la­tion Musca the Fly, with stars in a rough cross shape around Alpha Muscae. Anti-clockwise of the Cross lies the imag­i­na­tively named Southern Triangle (Triangulum Australe), and Ara the Altar, which abuts the Scorpion. Also in the area (but dim) are Norma the Set Square, Circinus the Compasses and Apus the Bird of Paradise. The region around the Cross is full of sights for users of binoc­u­lars or small tele­scopes. The Milky Way runs behind the Cross, the Pointers, the Triangle and Ara. A large dark nebula dubbed the Coal Sack, and looking like a hole through the Milky Way, touches the Cross between Alpha and Beta Crucis. It is prom­i­nent on a dark night. Squeezed between the Coal Sack and Beta Crucis is the Jewel Box (N4755), a multi-coloured open cluster of at least 50 stars grouped around the red giant Kappa Crucis. On the other side of the Cross, a diffuse nebula sur­rounds the star Lambda Crucis. In the upper reaches of the Centaur are two sights worth seeking out. They lie less than 5 degrees apart. One is the giant ellip­ti­cal galaxy Centaurus A (N5128, mag­ni­tude 6.9), with two semi­cir­cu­lar seg­ments sep­ar­ated by a dark lane of dust. Though rel­a­tively faint, it is half the width of the Full Moon and among the bright­est and largest of the exter­ nal gal­ax­ies (near 13 hr 25, 43 deg.). The other, lying 4 degrees closer to the pole, is among the real jewels of the south­ern sky. The glob­u­lar cluster Omega Centauri (N5139) is almost the size of the Full Moon, and an easy naked-eye object at mag­ni­tude 3.8 (near 13 hr 26, 47.5 deg.). Binoculars will reveal its unstar-like fuz­zi­ness and may reveal indi­vid­ual stars in out­ly­ing regions. It is bright because it is close (16,000 light years) as glob­u­lar clus­ters go. Large tele­scopes are needed to resolve the hun­ dreds of thou­sands of stars that fill it.

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1

–80°

HYI

4

–70°

L

T K

U

OCTANS

Z

T

K W I

H

3195

E

D D

Z

A

E K

P

I

4372

S

CARINA

2

E L

M

A

H

B Q Z

z1 z2

L

A

Q 

3766

T

E

3532

Acrux

VELA

5316

G

e

G T

E C1

K

R

w

4560

Z

I T

O

B

U

K

J

Y

U 2

c2 c1

Y

LIBRA

Q

n

5897

y

I

T

3 1

EC

LIP

u

–20°

HYDRA

2 5102

S

58

Menkent z

16h

T

LUPUS

a

d

I

R

N

5128

l

C

J

H

C

X

Y

k

J

5643

T

–30°

5986 h

b

M

B

–40°

G

e

L

10

Q

H

W

E

U

W

CENTAURUS

D

d

D

I.4406

5139

C3

N M

GG

Omega Centauri

f

H

g

A

U

4945

6124

L

SCORPIUS

5882

P

a

X X

S

D

–50° C2

N

b

N

K H

17h

M E

NORMA

Z

M F

M

M

Q

H

c

S E

6281 6242

N

V

Q

L

6302

Tr24

6231

E

R

5822

R

L M

Z Z

G

D

K

G

RS

6193

K

5617

B

U

H

A

4755

Gacrux

R

Shaula Lesath

T

B

5662 v

A

P

E

G

G

Q

Q



6067

D

J

I

B

CRUX

3918

Z

K

Q

6388

I

6087

I I

E

H

A

Hadar

Mimosa

D

O 

5281

m

4609

U u

S

S

I.4651

Rigel Kent

Z

H

Z

Proxima Centauri

5189

6025

TRIANGULUM AUSTRALE

5315

R

I.2602

Q

–60°

Z

CIRCINUS

4833

MUSCA

–70°

G

B

A

K

I I

E

Z

D E

D

G

H

18h L

ARA I

I

6541

M

B Q

X

I K

A

6397

P

G

K

CHAMAELEON

E

Q

D

Q

S

CORONA AUSTRALIS

I

APUS H

Q

6362

Z

K

B

G

I

B

M

D

A

Atria

M

Z

G D D 

D

Z

H

P P

D

H

K

TELESCOPIUM X

P

R

–40° H

H

N

C

Z

I

PAVO

South Celestial Pole

MENSA

–80°

L

Q

J

S

–90°

R

–50° L

TIC

TZ

–60° W

6744

12h

13h

MAGNITUDES

6

5

4

9

–30°

14h

15h

–20°

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­53

S_Sky_Guide_TEXT_3ed_03.indd 53

7/5/08 11:32:59 AM

CHART 4 18 Hours to 24 Hours RA 90 to 40 degrees Dec

This chart indi­cates how unevenly the wonders of the heaven are spread. In com­par­is­ on with the glories of the stretch of sky lying clock­wise from it, this region is barren, with no bright stars and few con­stel­la­tions of inter­est. It is all but bereft of bright nebulae and open clus­ters; the Milky Way, along the length of which those sights are con­cen­trated, just clips one edge. The con­stel­la­tions here are mostly of modern origin and gen­er­ally devoid of leg­en­dary asso­ci­a­tions. A few birds are rep­re­sented by group­ings of faint stars (Pavo the Peacock, Grus the Crane and much of Tucana the Toucan) along with Indus the Indian and a clutch of sci­en­tific instru­ments (Telescopium, Octans and a bit of Microscopium). Pavo is about the only ast­er­ism here with a story. Ancient legend says that Argos, builder of the mighty Argo which sails nearby, was changed into a peacock when the ship was taken into the heavens. The brighter stars of Grus form a notable lop­sided pattern with Fomalhaut in the Southern Fish further away from the Pole (see Chart 12). Octans the Octant (an instru­ment for meas­ur­ing angles) is of note as the con­stel­la­tion in which the South Celestial Pole cur­rently lies. The fifth mag­ni­tude star Sigma Octantis is the naked-eye star closest to the Pole, and so is the south­ ern equiv­al­ent of Polaris the North Pole Star (though Polaris is much brighter). Among the few things worth search­ing for with binoc­u­lars are the largish glob­u­lar cluster N6752 (mag­ni­tude 5.4, 20 diam­e­ter) in Pavo (near 19 hr 10, 60 deg.), and about 5 degrees pole­wards, the mag­ni­tude 8.5 galaxy N6744. Dunlop (delta) 227 in Telescopium (near 19 hr 50, 55 deg.) is worth a look; an attrac­tive double, yellow and white, 5.8 and 6.5, sep­ar­a­tion an easy 23 arc seconds.

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2

–80°

CHA

TZ

H

T

B

W

L

–50° W

R

H

B

–40°

X

M

Z

P

K

Ankaa

H

55

E

T

E

S

Y

0h

R

N

Q

G

TUCANA

N

I

A D D

M M

OCTANS

G

APUS

D

O

B

O

E

J

K

N

H

3

T

I

A Atria

D

P

L

J

G

B

G R

L

P

U

G

X

TELESCOPIUM

I

H

I

Z

Q

N

I

A

E

S

D

PISCIS AUSTRINUS

D

6541

H

SCORPIUS

I

–40° Q

K

I

K

Rukbat

G B

D

Z

A

D

Q

B

M

CORONA AUSTRALIS

A

I

24

Z

H

Q

Q

E

MICROSCOPIUM

B H

6388

H 22h Q

Z

K K

BArkab

–30°

Q

Z

A

I

L

A

T

M

K

K

L

18h

E G

A

19h

W

Q

M55

11

J

C

Y

SAGITTARIUS

6723

MAGNITUDES

4

12

Q

M

5

B

X

6397

6

N M L

T

N 227

I.4651

M

Q

H

–50°

Alnair

I

H 6752

M

E

S S

D

A

23h

I.1459

R

D

P P

M

W

X

D

U

A

ARA

E

Q

GRUS

N I

B

T

Peacock

H

Z

J

B

INDUS

J

PAVO

6744

Q

T 

D

R

6362

–60°

B

K

Z

TRA

M

E

E

P

M

I

G

U

Z

SCL B

Z

H

A

Y SX

S

–70°

A

PHOENIX

E

P

–80°

L

L

B 

X

P R

P

R

Q

U

C

L

47 Tuc (104)

G

G

L

Q

B

G

–90° S

K

D

SMC L

South Celestial Pole

I

362

T

R

Z

–60° I

K

HYDRUS

S T

M

1

–70° M

MENSA

–30°

H

20h

TIC

Q

LIP

CAPRICORNUS

RR

–20°

EC

21h

–20°

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

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7/5/08 11:33:01 AM

CHART 5 0 Hours to 3 Hours RA 40 to 10 degrees Dec

When we survey this stretch of night sky, we are looking at right angles to the plane of the galaxy. The South Galactic Pole (SGP) lies here (in Sculptor near 0 hr 50, 27 deg.). So we are well away from the riches of the Milky Way. Bright stars, clus­ters and nebulae are rare. On the other hand, we are able to look almost unim­peded into inter­ga­lac­tic space, and so glimpse some of the nearer exter­nal gal­ax­ies (extra­ga­lac­tic nebulae) hidden from us in other parts of the sky by the rich­ness of our own star system. These lie mostly in Sculptor and Fornax. The same is true around the North Galactic Pole, which lies in Coma Berenices (see Chart 17). The largest and bright­est con­stel­la­tion here, cov­er­ing most of the region, is Cetus the Sea Monster (or Whale), fourth largest of all the con­stel­la­tions (after Hydra, Virgo and Ursa Major). Cetus was com­monly shown in old star pic­tures as swim­ming in the nearby river Eridanus or resting on its bank. According to ancient legend, Cetus was the beast sent to devour the maiden Andromeda, so it is linked to con­stel­la­tions which lie further north in the sky (see Chart 13). The stars of Cetus form two rough poly­gons. The larger to the south-west makes up the body of the beast, the smaller to the north-east (where it abuts Aries and Pisces) forms the head. Beta Ceti at mag­ni­tude 2.4 is usually the bright­est star in the con­stel­la­tion (Alpha Ceti bears the name Menkar, meaning ‘nose’). Of far more inter­est is Omicron Ceti, lying about 30 degrees north-east of Beta, halfway along the creature’s neck. Otherwise known as Mira (the Wonderful Star), this was the first star observed to change its bright­ness over time. Its status as a ‘var­i­able star’ was estab­lished in the mid-seven­teenth century. Over a period of 11 months it moves from mag­ni­tude 2 to mag­ni­tude 10 and back again. At its bright­est it out­shines Beta; at its faint­est it becomes invis­ible in binoc­u­lars. Many ‘Mira variables’ are found in other parts of the sky. South of Cetus lie more modern con­stel­la­tions; Fornax the Furnace and Sculptor the Sculptor’s Chisel. These are faint but contain numbers of gal­ax­ies, some of which can be seen in binoc­u­lars. Two such lie in Sculptor; N55 (mag­ ni­tude 7.4, near 0 hr 15, 39 deg.) and N253 (mag­ni­tude 7.2, near 0 hr 50, 25 deg.). None of the numer­ous gal­ ax­ies in Fornax are brighter than mag­ni­tude 8.9. Close to the eastern edge of Fornax lies the rel­a­tively large (one third diam­e­ter of the Moon) plan­e­tary nebula N1360 (mag­ni­tude 9.4) with a bright central star (near 3 hr 30, 26 deg.). Polewards of Fornax lies the double star Theta Eridani (near 3 hr, 40 deg.), with a pair of white or yellow stars (mag­ni­tudes 3.4, 4.4) sep­ar­ated by 8.5 arc seconds.

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7/5/08 11:33:01 AM

23h

0h Q

E

J

e

–40°

s

y

J

Acamar

U

1291

Q

I

55

L

1316

X

L 300

L

7793

M

S

SCULPTOR

Z D

I

K

T

A SGP

A

 I I

N

613

–30°

1097

M

P

K

D B

P

R

S

E

Z

G

K

T

99 98

T 7

T

T

–20°

T

B

2

12

1232

T

U

247

T 1398 1360

G

W

288 253

i

FORNAX

L

J

H

g

1365 1399

H H

H

Q

G

–20°

f

h

B

–30°

HOROLOGIUM 4h

ERIDANUS

C G

Ankaa

PSA

Y

N

A

U

3h

K

K

PHOENIX

GRUS

2h

B

M

I

–40°

1D

1h

6

Deneb Kaitos R

Baten Kaitos

T

W

W

ERIDANUS

S P

–10°

J

AQUARIUS

J

J

R

J C

H

I

E

Z

–10°

Z

Z

H

Q

R

AR

R

R

30

CETUS O

Mira

0°

0° XZ

EC

L

D

LIP

TIC

G

Alrescha

A

X

TX

I

PISCES

W

M D

+10°

E

Z

1h

MAGNITUDES

4

K

N

N

X

O

X M

13

2h

O

L

X +10°

ARIES

X

0h

5

Menkar

A

PEGASUS

6

TAU

M77

3h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­57

S_Sky_Guide_TEXT_3ed_03.indd 57

7/5/08 11:33:03 AM

Chart 6 3 Hours to 6 Hours RA 40 to 10 degrees Dec

Orion the Hunter, one of the glories of the heavens and perhaps the best known of all con­stel­la­tions, lies at the north­ ern end of this stretch of night sky, just west of the Milky Way. Its stars strad­dle the celes­tial equator, always rising and setting due east and west. The sight of this majes­tic con­stel­la­tion rising late in the evening is a sign that the Southern Hemisphere summer is at hand. In the centre of the group is the well-known ‘saucepan’, though the three bright­ish stars marking the base of the pan actu­ally rep­re­sent Orion’s belt and the handle is his sword. The jewel in the sword is the pale green glow of the Orion Nebula (M42/N1976). This shows up pink or red in most photo­graphs due to the dif­fer­ent colour sen­si­tiv­ities of the human eye and photo­graphic film. Film picks up the red glow from hydro­gen, while the eye is more sen­si­tive to the green colour of glowing oxygen. But it is a stun­ning sight, what­ever you use to view it. Strangely, Galileo did not mention it when first viewing the night sky with his tele­scope in 1609. M42 (and nearby M43/N1982 which is part of the same nebula) lies about 1300 light years away. It is a ‘stellar nursery’ like many such nebulae. Imbedded in the 20-light-year-wide cloud of gas and dust is a cluster of (at least) four newly hatched blue stars (‘the Trapezium’), which appear as one to the naked eye (Theta Orionis). Other bright­ ish stars and star clus­ters are grouped around, making the area a great sight in binoc­u­lars. For example, the cluster N1980 (mag­ni­tude 2.5, diam­et­er 20) marks the end of the sword. N1980 con­tains a couple of multi­ple stars, includ­ing the double Iota Orionis, with stars of mag­ni­tude 3 and 7 sep­ar­ated by 12 arc seconds. N1981 is an open cluster to the north (nearer the belt) Surrounding the ‘saucepan’ are bright stars rep­re­sent­ing Orion’s body. When Orion is highest in the sky, early on summer even­ings, we in the Southern Hemisphere see him stand­ing on his head. To the north the red giant Betelgeuse (cur­rently tenth bright­est among the stars) and the fainter Bellatrix (the Female Warrior) mark the arms and shoul­ ders; to the south the bril­liant blue-white Rigel (seventh bright­est) locates one of his feet. Betelgeuse means ‘arm’ or ‘shoulder’, Rigel means ‘foot’. When Orion is rising, Rigel is always the first bright star of the con­stel­la­tion to be seen from south­ern lat­it­udes. Betelgeuse is a var­ia­ ble star like many red giants, and is often fainter than Rigel, even though it, not Rigel, is listed as Alpha Orionis. Betelgeuse shifts between mag­ni­tudes 0.4 and 1.3 over a period of around seven years. Orion is a hunter, warrior or giant in the star stories of many cul­tures. Traditional pic­tures in our culture have him armed with a club and net, accom­pa­nied by two dogs (Canis Major and Canis Minor) and fight­ing with a bull (Taurus). Those animals are on adjoin­ing pieces of sky. The rest of the region is dull in com­par­i­son. Lepus the Hare, with a quad­ri­lat­eral of bright­ish stars, is beneath the Hunter’s feet, with Columba the Dove further south again. East of Orion are the head­wa­ters of Eridanus. Much of this stretch of sky is taken up with the mean­der­ings of the hea­venly river. It takes a sharp turn around Fornax which intrudes from the west. Stars of Canis Major and Monoceros the Unicorn border this stretch of sky to the east, with Taurus and the head of Cetus the Sea Monster to the north and west. Delta Orionis (the most west­erly of the stars in the Belt) is a wide double (2.2. and 6.8, white and violet, 53 seconds of arc). The region has a couple of Mira-type var­i­ables, R Lep (from 5.5 to 11.7 in 432 days, near 5 hr, 15 deg.) and U Ori (4.8 to 12.6 every 372 days, near 5 hr 55, 20 deg.). The Orionids meteor shower, asso­ciated with Comet Halley, emerges from the north-eastern part of Orion (close to its border with Gemini) around 16 to 27 October, peaking on 22 October.

­­58

S_Sky_Guide_TEXT_3ed_03.indd 58

7/5/08 11:33:03 AM

2h

3h

1

4h

J

5h

6h

1433

PHOENIX –40°

D

e

I

Q

Acamar

PUPPIS

PICTOR

HOROLOGIUM

s

7h

H

CAELUM

A

D

1291

P

N

C

–40°

P

A

y 1851

L J

H H H

L

1316

h

1365

i

B

M

U

R S

T Z

G

L –30°

Z

S

Furud

Z

CANIS MAJOR

U

1398 1360

T

T

T

T

X

G

T

B

E

T

1232

X

S

M79

T

T –20°

K

D

L M

COLUMBA

D

A

G

K

G

A

Phact 41

FORNAX

I

W

B

43

1097

I

K

Wazn

E

G

1399

–30°

1808

B

g

SX

Q

X

f

D

Nihal

T

N N

Mirzam

54

B

Arneb

5 ERIDANUS

M

LEPUS

P E

Zaurak

53

G

Z

–10°

R

RX

E

Z

R

R

L

D

L N

O

Saiph

O

W X

N

B Cursa

I

M42 / M43 Orion Nebula 1981 I.434 Horsehead Nebula S

Q 

1973/75/77

M H

E Alnilam

A

ORION P

N L

M

O

3h

4h

MAGNITUDES

G

W 32

J P

88

Y

8 T

A

Betelgeuse

P

M

X

Bellatrix

P

ARIES

4

R

P

TAURUS

0°

M78

W

P

N

V

2024

Mintaka

K

Menkar

B

2232

Alnitak

Z

D

G

G

1980

10

5

MONOCEROS

U

T

M77

6

I.2165

–10°

29

Y

Beid

32

+10°

Q

H

I.418

B Rigel

Keid

CETUS

D

I

Z

K

H

0°

K

1535

P

N

7

A

S

–20°

L

1662

14

J

M

+10°

Meissa

5h

6h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­59

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7/5/08 11:33:05 AM

Chart 7 6 Hours to 9 Hours RA 40 to 10 degrees Dec

This region of sky is dom­i­nated by the pres­ence of stars rep­re­sent­ing two dogs. They could rep­re­sent many dif­fer­ent dogs, such as Cerebus the three-headed dog that guarded the way to Hell, but they are usually thought of as the com­ pan­ions of Orion the Hunter to the west. Between Canis Major (the Big Dog) and Canis Minor (the Little Dog) runs the Milky Way, while between the Little Dog and his master are incon­spic­u­ous stars belong­ing to Monoceros the Unicorn. The open cluster N2244, close to Eta in Monoceros (near 6 hr 30, 15 deg.), is a naked-eye object, at 4.8 mag­ni­tude, with 16 stars in a huddle visible with optical aid. Powerful tele­scopes reveal the sur­round­ing Rosette Nebula (N2237), the faintly glowing cloud of gas from which the stars formed. Both the Dogs are worth watch­ing. Alpha Canis Majoris is Sirius, the bright­est star in the sky other than the Sun. Its name means the ‘shining one’ or ‘scorch­ing one’. Old pic­tures have it marking the eye or heart of the Dog. Beta Canis Majoris or Mirzam nearby is a front leg and a tri­an­gle of bright­ish stars to the south show the hind­quar­ters. The bright­est of these, Adhara, is the second bright­est star in the con­stel­la­tion, even though it is listed only as Epsilon. Sirius is one of the nearest stars, lying less than nine light years from the Sun. It was an impor­tant element in the cal­en­dars of ancient peoples. The first appear­ance of Sirius (or Soothis) in the rays of the rising Sun (the helical rising) was taken by the Egyptians of 2000 BC as a sign that the Nile was about to flood. The less spec­tac­u­lar Little Dog has Procyon, eighth on the list of bright­est stars. Beta Canis Minoris, a few degrees away, makes a dis­tinc­tive pairing. Both Sirius and Procyon have faint white dwarf com­pan­ions and are among the 20 stars lying within 12 light years of the Sun Two of the four con­stel­la­tions that for­merly made up Argo Navis (the Ship Argo) are in this part of the sky; namely, the roughly rec­tan­gu­lar Puppis the Poop, which lies south-east of Canis Major and, to the east of Puppis, the incon­ se­quen­tial Pyxis the Compass. The other two star groups (Vela the Sail and Carina the Keel) are further south. Intruding into the region from the east is the head of Hydra the Water Snake, lying east of Canis Minor. The pres­ence of the Milky Way ensures the avail­abil­ity of sky sights worth inves­ti­gat­ing with the help of binoc­u­lars. These include the fol­low­ing open clus­ters: •  N2451 (mag­ni­tude 2.8, diam­e­ter 50 seconds of arc), just west of the Milky Way in the midst of Puppis. •  N2354 and N2362, two clus­ters among the rump stars of Canis Major, with N2354 both fainter and larger (mag­ni­tude 6.5, diam­e­ter 20) than its very near neigh­bour (mag­ni­tude 4.1, diam­e­ter 8). •  N2287 (M41) (mag­ni­tude 4.1, diam­e­ter 38) about 4 degrees south of Sirius. •  N2423 (M47) on the Milky Way at the north­ern end of Puppis (mag­ni­tude 4.4, diam­e­ter 25). N2437 (M46) is nearby (magnitude 6.1, diam­e­ter 20). •  N2548 (M48) (mag­ni­tude 5.8, diam­e­ter 54) east of the Milky Way on the Hydra/Monoceros border. Two double stars are asso­ciated with M47; Struve (sigma) 1121 has com­po­nents both mag­ni­tude 8 lying 8 seconds of arc apart; in Struve (sigma) 1120, stars of mag­ni­tude 5.6 and 9.5 are sep­ar­ated by 20 arc seconds. If you are looking for other double stars, k Puppis, at the north­ern end of Puppis (5 degrees east of Delta Canis Majoris), boasts a pair of matched fifth mag­ni­tude yellow stars lying about 10 arc seconds apart. Nearby Adhara (Epsilon CMa) is also double but a much tougher call, with mag­ni­tude 1.5 and 7.4 stars sep­ar­ated by 7.5 seconds of arc.

­­60

S_Sky_Guide_TEXT_3ed_03.indd 60

7/5/08 11:33:05 AM

5h

6h

2

7h

8h

–40°

Q

I

PICTOR

CAE

H

1851

L2

N

P P

10h

g

a

VELA

O e

T

E

A

Phact

Q

F

x

K

G

Aludra

E S

–20°

Nihal

B

CANIS MAJOR X

2354

O

X

H

O

Z

16

G

3 1120

Q Saiph

2343

12

2539

A

U

2353

–10° A

Alphard

M50

B G 2232

I.434 Horsehead Nebula

Z

M46

2438

3 1097

K

M42 / M43 Orion Nebula 1973/75/77

3 1121

M47 2423

I.2165

1980

8

R

A Sirius

Q

H

–10°

S

–20°

2440

M

D

G

M93

P I

1981

Q

K

PYXIS

R

Q

11

N N N

Mirzam

B

6

I Q 

X

n

S

D

G H

2467

m

T

L

M41

A Arnab

U

E

2527

O

2997

Z

–30°

MZ

3 k

2362

Z

A

Z

p

W

D

Wezen

D

B

2439

M79 S

ANTLIA

r

PUPPIS

Adhara

E

q

w

K

Furud

G

l 2 k1 k

2546

2451

e

z

Z

LEPUS

Z

b

h

h2 h1

f

L

S

Naos

2477

D

M

a

c

d1-3

v2

v1

L

y

P

SX

B

A

COLUMBA

–30°

X

Wazn

E

–40°

Y w

D

G

z

d

C 1808

y

L

N

S

M

b

AH P

L1

9h

n

G

J

Alnitak

2024

E Alnilam Mintaka M78

0°

C

MONOCEROS

V

ORION

HYDRA

M48

10

Z 0°

D 2301

10 2244 8

A

M

14

S

A

H

2264

S

Gomeisa

G

B

LEO

CANCER M67

6h

7h

MAGNITUDES

6

5

4

15

Z

E

H B E

W

R

D

Procyon

13

L Meissa

BC

D

CANIS MINOR

Rosette Nebula 2237

T

Betelgeuse

J J  +10°

D

Q

Z

D W

+10° Acubens

K

A 9h

8h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­61

S_Sky_Guide_TEXT_3ed_03.indd 61

7/5/08 11:33:07 AM

Chart 8 9 Hours to 12 Hours RA 40 to 10 degrees Dec

There is not a lot to note in this part of the sky, lying as it does well east of the Milky Way and south of the eclip­tic. A little of the Zodiac sign Virgo the Young Maiden lies to the north-east, hosting (at the present epoch) the north­ern autumn equinox. This lies where the eclip­tic, pushing south-east, cuts the celes­tial equator at the merid­ian making 12 hours of RA. Much of it is taken up with the long line of stars marking Hydra the Female Water Snake, one of the leg­en­dary foes of the hero Hercules. Orange-coloured Alpha Hydrae, at mag­ni­tude 2, stands out due to the lack of other bright stars near it. Its name Alphard means (appro­pri­ately) ‘the sol­i­tary one’. Some 15 degrees north-west near Cancer the Crab, a small col­lec­tion of faint­ish stars indi­cates the beast’s head. The tail of the water snake con­tin­ues to the east, winding past Corvus the Crow and almost to Libra. Though faint, Hydra can boast of being the largest of the rec­og­nised 88 con­stel­la­tions. Covering 1300 square degrees, it sur­passes Virgo, Ursa Major, Cetus and Hercules, the biggest of the rest. Hydra stretches a quarter of the way around the sky, from east of Canis Major to just north of Centaurus. The rest of the region is taken up with faint and gen­er­ally unmem­or­able con­stel­la­tions; Sextans the Sextant and Antlia the Air Pump (all sorts of sci­en­tific instru­ments find a place among the south­ern stars!), and Crater the Cup. Crater does have a story linking it to Hydra and also to Corvus to the east. The Crow was sent by his master Apollo to fetch a drink. He dallied by a fig tree, waiting for the fruit to ripen. Being late back, he blamed the snake for delay­ing him. Worth search­ing for with binoc­u­lars or a small tele­scope is the plan­e­tary nebula N3242, located some 12 degrees south-east of Alphard (that is, near 11 hr 30, 18 deg.). At mag­ni­tude 7.8, it is among the three bright­est such objects in the sky. From its appear­ance, it is some­times dubbed ‘the ghost of Jupiter’ (and may help to explain the mis­lead­ing term ‘plan­e­tary nebula’!). Twenty degrees almost due south, on the Antilla/Vela border, lies N3132, another plan­e­tary nebula rated at magnitude 9 but with a bright central star.

­­62

S_Sky_Guide_TEXT_3ed_03.indd 62

7/5/08 11:33:08 AM

N

–40°

8h

h1

B

i

q

l k 1 k2

l

U

B

X1

I

E

H

w

A

O 3621

Z Z E

Z

L

D

G

H

A

2997

K

p

–30°

X

D

HYDRA

S

C

Q

Q

C

A

I

B

7

3242

K

A

U

Z

L

Y

Alkes

G

H

Algorab H

CORVUS I

U

K –10°

E Q

A

Alphard

G 3115

VIRGO

SEXTANS HYDRA

J

T

D T

0°

I

Zaniah

p1

A

H

U

B 3521

D

R

T

W

Z

CANCER Acubens

S

K

X

N W

LEO R

31

P

4365

O

X

+10°

I

O

10h

A

Regulus

MAGNITUDES

4

M61

C

P

W

A 9h

5

Zavijava

TIC

VY

+10° M67

0°

LIP

EC

E

6

B

Q

H

S

9

D

L

–10°

D

Gienah

G

N

U

–20° R

b1

J

M

B Z

CRATER

b3

12

Alchiba

E

b2

M68

3585

G

–20°

X2

B

ANTLIA

PYXIS

–30°

–40°

u

r

3132

PUPPIS

CENTAURUS n

Y

r

13h D

y

w

q

t

3201

u

12h

C2 C1

s z

h

11h

p

m

VELA

d

h2

2

10h c

f g

L

e

Naos

Z

9h

a

16

11h

4371

12h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­63

S_Sky_Guide_TEXT_3ed_03.indd 63

7/5/08 11:33:09 AM

Chart 9 12 Hours to 15 Hours RA 40 to 10 degrees Dec

With the eclip­tic passing though this zone of sky, we have on display one of the more dis­tin­guished of the signs of the Zodiac, Virgo the Young Maiden. Rated as the second largest of the con­stel­la­tions,Virgo meas­ures more than 30 degrees (three fist widths) in both direc­tions. The Sun in its yearly journey through the zodiac reaches the western parts of Virgo around 21 September, which is the spring equinox for the Southern Hemisphere (the autum­nal equinox for north­ern lat­i­tudes). The stars of Virgo are not out­stand­ingly bright, other than the blue-white Spica, which is almost on the eclip­tic. In dif­fer­ent cul­tures, Virgo could stand for any number of young and inno­cent maidens. In the best-known rep­re­sen­ ta­tion, Virgo is a goddess of spring or of the harvest, perhaps Persephone, the daugh­ter of Ceres. Spica rep­re­sents an ear of wheat in her hand. In other pic­tures, Virgo is the blind­folded Justina or Astraea, the goddess of justice, weigh­ing truth and inno­cence on the scales that form the zodiac sign Libra, which lies to the east. The north-western sector of Virgo, together with parts of con­stel­la­tions further north, is notable for the pres­ence of a major col­lec­tion of exter­nal gal­ax­ies, known as the Virgo Cluster and con­tain­ing many hun­dreds of ‘island universes’ at dis­tances esti­mated at 40 or 50 million light years. Some of these are visible as faint smudges in small tele­scopes or even binoc­u­lars. The bright­est is N4472 (M49) in Virgo, at mag­ni­tude 8.4 (near 12 hr 30, 8 deg.). Some 20 gal­ax­ies at mag­ni­tude 10 or brighter can be found in the 10 degree square patch of sky north of M49, with the largest in actual size being the giant ellip­ti­cal galaxy M87 (N4486). As for other con­stel­la­tions in the area: the dis­tinc­tive rhom­boid of second and third mag­ni­tude stars rep­re­sent­ing Corvus the Crow lies south-west of Virgo. On the Virgo/Corvus border (near 12 hr 40, 12 deg.) lies N4594 (M104), the famous ‘Sombrero Hat’ galaxy (mag­ni­tude 8.3, diam­e­ter 9). South of Corvus sprawls the tail of Hydra, the female water snake, the rest of which lies to the west. The story linking Hydra, Corvus and Crater is told in the text for Chart 8. One inter­est­ing scale fallen from the tail is N5236 (M83), one of the bright­est exter­nal gal­ax­ies at mag­ni­tude 7.5 (diameter 11). It lies face on to the viewer (near 13 hr 37, 30 deg.).

­­64

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7/5/08 11:33:09 AM

11h

12h

VELA

3

13h 5139

B

W

D

i

14h

Omega Centauri

Z

I U

U

15h

A

–40°

L

a

T T

O

5643

I.4406

ANT

5128

l

u

O

X1

B

3621

J

X2

X

D

K

GG

z

y

–40°

U

a

CENTAURUS

p

W G H k

5986

h

J

Y

5102

g

d

C

d

I

E

e

B

H

M N

n

16h 5882

b

Y

J

Q

c1

Menkent

LUPUS

c2

C

Y

2 T

–30°

1

–30°

T

3 2

r M83

U 58

HYDRA

M68

A

CRATER

P

S

Alchiba

E

B

Z

–20°

Y

G

R

5897

I

L

–20°

5068

Z

R

G

8

H

Z

G

Gienah

Algorab

Zubenelgenubi

D H

CORVUS

I

L Sombrero Galaxy

Q

LIBRA

Spica

X X

E

–10°

B

K

A

Y C

O

N

M

M104

–10°

10 A 

D

Zubeneschamali

4699 S

4697

0°

U

Zaniah

H

I

Q

VIRGO

G Porrima

M

U

J 0°

Z

4753

B

Zavijava

4365

X

M49

O

R 4526 4535 5248

R

LEO

4371

M59 M60

12h

E

5

4

+10°

BOOTES

Vindemiatrix

13h

MAGNITUDES

6

SERPENS CAPUT

S

P

+10°

M5

D

M61

W

110

109

T

4636

N

16

17

14h

15h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­65

S_Sky_Guide_TEXT_3ed_03.indd 65

7/5/08 11:33:11 AM

Chart 10 15 to 18 Hours RA 40 to 10 degrees Dec

In one of the most spec­tac­ul­ar regions of the night sky, we here reach the Milky Way at its widest and densest, and dis­cover the stun­ning con­stel­la­tion Scorpius the Scorpion. For once little imag­i­na­tion is needed to see the crea­ture among the stars. The hook of stars that rep­re­sents the Scorpion’s tail cer­tainly invites that inter­pre­ta­tion, but other images are pos­sible. The New Zealand Maoris saw in it the fish hook which one of their leg­en­dary heroes baited with his own blood and then dragged up the South Island from beneath the sea. In legend, the Scorpion and Orion the Hunter were deadly enemies, with the beast sting­ing Orion to death. So one is always rising as the other sets. The heart of the Scorpion is marked by the red giant star Antares (Alpha Scorpii), so named from its sim­i­lar­ity in colour to the planet Ares (Mars). A close approach of Mars and Antares (which happens every few years since Antares lies very close to the eclip­tic) will soon confirm the com­par­i­son. A degree or so west of Antares lies the glob­u­lar cluster N6121 (M4), one of the larger and brighter exam­ples at mag­ni­tude 5.8 and diam­e­ter 26. A line of three bright stars west of Antares marks the creature’s claws. The tail, com­ plete with a close pair of stars to indi­cate the sting, coils towards the south-east, lying across the Milky Way. The brighter of the ‘sting stars’ is Shaula (Gamma Scorpii), second bright­est in the con­stel­la­tion. This stretch of sky has many good targets for binoc­u­lars. North-east of the sting are a pair of notice­able open clus­ ters: N6405 (M6, the Butterfly Cluster, mag­ni­tude 4.2, diam­e­ter 33), and a few degrees away, the larger and brighter N6475 (M7, mag­ni­tude 3.3, diam­et­er 80). Brighter but smaller than either of these is N6231 (mag­ni­tude 2.6, diam­ e­ter 26), which lies on the curve of the Scorpion’s tail. Very close and just to the north is the open cluster Trumpler 24 (mag­ni­tude about 5, diam­e­ter 60). Among the double stars visible in binoc­u­lars is Beta Scorpii, marking the left claw (mag­ni­tudes 2.6 and 4.9, sep­ ar­a­tion 13 seconds of arc). Antares is itself double, but with the primary much brighter than the sec­on­dary and only 3 seconds away, it is a chal­lenge even in a 80 mm tele­scope. North-west along the eclip­tic, between Scorpius and Virgo the Young Maiden (see Chart 9), two bright­ish stars almost a fist width apart, together with a few fainter ones further east, make up the zodiac sign Libra the Scales, almost cer­tainly those of Justice. In some ancient maps, the stars of Libra are blended with those of Scorpius to produce greatly enlarged claws. In fact, the usual names for these two stars mean ‘the north­ern claw’ and ‘the south­ern claw’. Alpha Librae is a very wide double, with the com­po­nents 3.9 apart, but the mag­ni­tudes (2.8 and 5.2) mean most people will need binoc­u­lars. Scorpius played a key role in the devel­op­ment of astron­omy. Here in 134 BC the Greek astron­o­mer Hipparchos saw a ‘new star’ (a nova), the first on record. This led him to compile a detailed star map (so he could detect any other ‘new stars’). Comparing his charts with those from Babylon 2000 years before led to dis­cov­er­ies like the pre­ces­sion of the ­equinoxes. Although Scorpius is a zodiac sign, most of it lies way off the eclip­tic to the south. The Sun, Moon and planets, when in this region, are likely to be located not in Scorpius but in the south­ern parts of the con­stel­la­tion of Ophiuchus the Serpent-Holder, which lies imme­di­ately to the north. A long polygon of stars marks where a man is appar­ently wres­ tling with a serpent, while the beast itself rates sep­ar­ate star group­ings to indi­cate its head (Serpens Caput to the west) and its tail (Serpens Cauda to the east.) The bright­est star in the con­stel­la­tion (Rasalhague or ‘the head of the serpent charmer’) can be found where Ophiuchus con­tin­ues to the north on Chart 18. Ophiuchus, like many star signs, has more than one inter­pre­ta­tion. One is that it rep­re­sents Aesculapius, the ship’s doctor on the Argo and the founder of modern med­i­cine. This was the man who tried to revive Orion after he was killed by the sting of the Scorpion. The serpent is another symbol of medical wisdom. Binocular sights in Ophiuchus include the open cluster I4665 (mag­ni­tude 4.2, diam­e­ter 70), which lies just north of the second bright­est star in the con­stel­la­tion (that is, near 17 hr 50, 8 degrees).

­­66

S_Sky_Guide_TEXT_3ed_03.indd 66

7/5/08 11:33:11 AM

14h

15h

T

J

I.4406

5643

C

–40°

W

Q

D

GG

Y

c1

Z

G

J

c2

5986

6242 6281

Y

N

58

5897

L

K A 

N

–20° Y

M24 Star Cloud

H

M17 Omega Nebula

X O

SERPENS CAUDA N

Z

11 G

SCT

M

OPHIUCHUS

Y

M E

16

D

M

Yed Posterior

M10

Z

M14

Yed Prior

H

M12

0°

59 109

S

110

W

Y

M5

VIRGO

SERPENS CAPUT A

G

L S

E

Cebalrai

67

70

B I.4665 6633

Unukalhai

6572

HERCULES

+10°

BOOTES

D

16h

MAGNITUDES

4

K

72

+10°

I

15h

5

0°

68

U

L

6

–10°

Z

T U

U

M16 Eagle Nebula

N

C

M25

M18

C

Y

Zubeneschamali

M

M23

M107

D

M22

M9

Sabik

E

L

M28

M20 M21

Trifid Nebula

48

B

Kaus Borealis

X

J

X

D Kaus Media

6530 M8

Lagoon Nebula

44

Y

H

G

ECLIPTIC

W

Q

O

Q

M19

N

Graffias B

X X

–10°

M80

–30°

J

R

U

Z

M

W W

36

O

O D

Zubenelgenubi

G

X

Antares

M70

Alnasl W

A

S

LIBRA

9

BM

T

S

I.4776

45

M62

M4

Kaus Australis

E

SAGITTARIUS

M6

R

P

I

RS

M69 6383

SCORPIUS

U

–20°

Shaula

RR

T

L

K

H

G

L

E

2

HYDRA

U

M7 H

X

C

CORONA AUSTRALIS

I

Lesath 6302

Y

–30°

K

Q

M

–40°

M I

Q

LUPUS

CENTAURUS

M

Z

H

Q

Tr24

H h

6541

6231

k

J

19h

Q

H

6124

U

b

Menkent

L

TEL H

6388

Z

A

E

S

RS

M

K

a

D

g

B

H

18h

I

NORMA

d

E

e

17h

E

Q

5882

L

O

3

16h

P

T

18

17h

A

Rasalhague

18h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

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S_Sky_Guide_TEXT_3ed_03.indd 67

7/5/08 11:33:13 AM

Chart 11 18 Hours to 21 Hours RA 40 to 10 degrees Dec

Between Scorpius and the next zodiac sign, Sagittarius the Archer, at a point on the merid­ian marking 18 hours of right ascen­sion, the eclip­tic reaches its maximum dis­tance (23.5 degrees) south of the celes­tial equator. The Sun, arriv­ ing at this point around 21 December, then stands at the summer sol­stice for the south­ern hemi­sphere, marking the longest day of the year. It follows that these same stars will be passing over­head at mid­night six months earlier, around the end of June. Interestingly, at this same point the eclip­tic crosses the galac­tic equator, a line running down the centre of the Milky Way. Galactic lon­gi­tude here is less than 10 degrees, indi­cat­ing that the core of our wheel-shaped galac­tic system lies behind the stars in this region of the sky. A visual clue is the appear­ance of the Milky Way itself. Between Scorpius and Sagittarius it is wider and denser than at any other point along its length. Sagittarius the Archer stands in front of the Milky Way. A number of not very bright stars form a shape more sug­ ges­tive of a teapot than a Centaur firing an arrow at the heart of the Scorpion, as the old star pic­tures show. Still, the shape is quite strik­ing. The bright­est star is Epsilon Sagittarii, which is called Kaus Australis or the ‘south­ern bow’. Gamma Sagittarii has the name Alnasl, which means ‘the head of the arrow’, though the pedan­tic might say that the arrow looks like it will miss. From Sagittarius, the line of the Milky Way takes us north-east, through Serpens Cauda (the Tail of the Serpent) to Aquila the Eagle. Its first mag­ni­tude star Altair is flanked by a fainter star. For more on Aquila see Chart 19. South of Aquila lies the tiny con­stel­la­tion of Scutum the Shield, notable mostly from the open cluster N6705 (M11, ‘the Wild Duck nebula’, mag­ni­tude 6, diam­e­ter 10 minutes of arc). Binoculars show a misty patch, tele­scopes a glit­ ter­ing spray of more than 100 stars, fanned out like a flight of wild birds. For much of its length in this region of the sky the Milky Way appears split by a great cleft. This reveals the pres­ence of vast clouds of dust hanging in space in front of the Milky Way, cutting off the light from the stars behind. Binoculars will reveal some­thing more; many bright nebulae and star clus­ters seen against the light and dark of the Milky Way. These objects, like stars in general, are con­cen­trated into the plane of the galaxy. Even with binoc­ul­ars these can be a fine sight. The view through a small tele­scope is even better. This stretch of sky has an extraor­di­nary con­cen­tra­tion of Messier objects (see page 19), though indi­vid­u­ally brighter objects are found else­where. In a mere 10 degrees of arc along the galac­tic equator, begin­ning at the south-east corner of Serpens Cauda and moving south-west, we find: •  M16, the open cluster N6611, mag­ni­tude 6.0, diam­e­ter 21. •  M17, the ‘Swan Nebula’ N6618, mag­ni­tude 6.0, diam­e­ter 25. •  M18, the open cluster N6613, mag­ni­tude 6.9, diam­e­ter 8. •  M24, a ‘star cloud’, mag­ni­tude about 2 and 2 degrees by 1 degree in size. •  M21, the open cluster N6531, mag­ni­tude 5.9, diam­e­ter 15. •  M20, the ‘Trifid Nebula’ N6514, mag­ni­tude 6.3, diam­e­ter 30. •  M8, the ‘Lagoon Nebula’ N6523/30, mag­ni­tude 4.6, diam­e­ter 90. Both the Lagoon and Trifid Nebulae have small clus­ters of bright, young, blue stars within them. It is the ultra­vi­ol­et light pouring from these stars that makes the nebulae glow. Nor is that all the region offers. To name just a few others: 5 or 6 degrees east of M21 is the glob­u­lar cluster M22 (N6656, mag­ni­tude 5.1, diam­et­er 24). M22 is com­monly ranked third in impres­sive­ness among glob­u­lar clus­ters, behind Omega Centauri (see Chart 3) and 47 Tucanae (see Chart 1). A couple of degrees east of M24 is M25 (the open cluster I4725, mag­ni­tude 4.6, diam­e­ter 30). And 10 degrees south-west of M8 (close to the sting of the Scorpion) are the open clus­ters M7 and M6.

­­68

S_Sky_Guide_TEXT_3ed_03.indd 68

7/5/08 11:33:14 AM

17h Z Z

E

A D

6541

Q

SCORPIUS

Tr24

6281

U

L

K

BM

L

45 36

G

OPHIUCHUS

D Kaus Media

W

X

J 44

L

6530

Lagoon Nebula

M8

Trifid Nebula

X

M23

X M25 Y

SERPENS CAUDA

O

X

C C

52

C C

P R R U

B

6822

M16 Eagle Nebula

X

6818

Z

A

D

E

12

H

B

59

Q

6633

M

19h

4

G

B

T

X

A Tarazed

MAGNITUDES

5

U

R

X

EQUULEUS Kitalpha

S

6709

6

0°

E

Alya

18h

71

D

Q

B

H

Alshain

Rasalhague

M

AQUARIUS

N

72

–10°

Sadalsuud

L

67 70

OPHIUCHUS

N 7009

3

I

+10°

12

M73

K

U

0°

6572

M72

N

AQUILA

I.4756

–20°

T

Dabih

V

H

Cebalrai

I

Q

U

Albali

M11

I.4665

O R

M26

R

68

E

E

Y

Z

P

X A  Algedi

SCUTUM

J

H S

U

G

N T

RT

M75

M30

Z

CAPRICORNUS ECLIPTI

M18

M17 Omega Nebula

M

A

–30°

24

Y

W

Y

N N

–10°

B

Q

W

62

59

M22

M20 M21

X

G

E

G D

T

S

Kaus Borealis

M28

M24 Star Cloud

10

M14

B

M55

Z Ascella

Nunki

M

O

A

SAGITTARIUS

M54

I

MICROSCOPIUM Q

RR

Q

–20°

PISCIS AUSTRINUS

G

RY

M70

–40°

X

Q

A

E

I.4776

Alnasl

Q

H

G

Q

M69

K

Z

Kaus Australis

M6

GRUS

A

D

6723

E

RS

K

I

Rukbat

T

I

B

M7

–30°

Z



22h

INDUS

Z

N

B

M

H

6383

21h A

Arkab

H

CORONA AUSTRALIS

G

Shaula

20h

I

B

Q I

K

Q

Lesath

TELESCOPIUM

D H

I

6302

4

19h

6388

H

6231

–40°

18h

ARA

19

B

DELPHINUS K

Altair

E

O J

A

G

I

20h

+10° D

21h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

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S_Sky_Guide_TEXT_3ed_03.indd 69

7/5/08 11:33:16 AM

Chart 12 21 Hours to 24 Hours RA 40 to 10 degrees Dec

This is a dull stretch of sky with few bright stars. The inter­est is in the asso­ci­a­tions of the con­stel­la­tions. This region might be dubbed the ‘wet corner of the sky’, since many of the con­stel­la­tions here and nearby have some­thing to do with water. They include the two zodiac signs Capricornus the Sea-Goat and Aquarius the Water-Carrier (as well as the next sign to come, Pisces the Fish), and Piscis Austrinus the Southern Fish. East of Aquarius lies Cetus the Sea Monster. Ancient people used the stars as a cal­en­dar. It may be that thou­sands of years ago (when these con­stel­la­tions were first named), the Sun in its yearly travels reached this part of the sky during or just before the wet season of the year. Certainly, Capricornus hosted the south­ern summer sol­stice (reached by the Sun around 21 December) 2000 years ago. The com­pil­ers of horo­scopes still use Capricornus to rep­re­sent people born in the month com­menc­ing 21 December, and geog­ra­phers use the term ‘Tropic of Capricorn’ to link those points on Earth at which the Sun is over­head at noon on that day. Neither the Sea-Goat, the figure of a goat with a fish’s tail, nor the Water-Carrier pouring out water from an urn on his shoul­der, have any bright stars. A pair of faint­ish stars about 3 degrees (a couple of fingers) apart at the western end of Capricornus are dis­tinc­tive. Both are wide doubles. Alpha Capricornii, to the north, is one for the keen naked eye, with stars of mag­ni­tudes 3.6 and 4.2 sep­ar­ated by 6.3 minutes of arc. They are marked sep­ar­ately on this chart. Beta is harder to see and binoc­u­lars are needed. Its 3.1 and 6.1 mag­ni­tude com­po­nents lie 3.4 minutes of arc apart. Aquarius is an ancient sign, dating back to Babylonian times, 4000 years or more ago. The stream pouring from the Water-Carrier’s urn or barrel rep­re­sented the time of the annual flood. N7293 (the Helix Nebula), which lies close to the south­ern boun­dary of Aquarius (near 22 hr 30, 21 deg.), is the closest and appar­ently largest of the plan­e­tary nebulae. Though half the size of the Full Moon, the nebula is quite faint. Binoculars reveal it as a misty patch. Aquarius is home to two meteor showers; the Eta Aquarids of early May (peaking 6 May), asso­ciated with Comet Halley, and the double-barrelled Delta Aquarids of late July and early August (peaking on July 29 and August 7). The bright­est star in the area is the first mag­ni­tude Fomalhaut in Piscis Austrinus. In old star pic­tures Aquarius was shown pouring a stream of water into the mouth of the Southern Fish, with Fomalhaut rep­re­sent­ing that mouth. With the three bright­est stars in Grus the Crane to the south, Fomalhaut makes up a dis­tinc­tive and easily rec­og­nised tra­pe­zium or cross, which rides high in the south­ern sky early in winter even­ings. Fomalhaut was one of the four Royal Stars of Ancient Persia, stars which marked points along the zodiac linked to the seasons. Four thou­sand years ago, the Sun would have neared Fomalhaut around north­ern mid winter (the sol­stice then lying among the dull stars of Aquarius just to the north). The other royal stars were Aldebaran in Taurus (marking north­ern spring), Regulus in Leo (north­ern summer) and Antares in Scorpius (north­ern autumn).

­­70

S_Sky_Guide_TEXT_3ed_03.indd 70

7/5/08 11:33:16 AM

TEL

20h

21h Z

N

I K

–40°

H

SAGITTARIUS

23h

A

INDUS

Q Q

Q

D

M

Z

S S

L

U

I

E

G

M

C

11

O U

–30°

M Z

I

K

K D

M30 88

U

E

–20°

T

Helix Nebula 7293

J

Q

G

86

Z

H

R

D

E

Z

CAPRICORNUS

S

7793

A

24

SCULPTOR H

P

B

L

–20° P

G

H

Y

B

Fomalhaut

W

300

Q

PISCIS AUSTRINUS T

L

55

U

N

Q

D

X L

I.1459

B

–40°

Ankaa

J

MICROSCOPIUM

–30°

A

PHOENIX

I

R

G A

K

I

M

X

1h E

Q

P P D

GRUS

0h

T

B

Alnair

I

K

4

22h

99

7

98

K

2

5

I

T

Nashira G D Deneb Algedi M72

D

CETUS

R

W

T T 

I

M

M73

Skat

AQUARIUS

W

N

–10°

–10°

7009

E

Albali

AQL

S

M

Y Y

Y X

Ancha

Q

Sadalsuud

3

C

L

R

I

J

B

30

K O

71

0°

M2

ECL

Sadachbia

IPTIC

G

A

Sadalmelik

Z

H

K

L

P E

EQUULEUS Kitalpha

N B

DELPHINUS +10°

B

A

K G

R Homam

21h

22h

MAGNITUDES

6

I

E

D

5

4

TX

PISCES W

Q

PEGASUS

Enif

E I

G

Biham

Q

0° XZ

Z

20

+10°

55

S

23h

0h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­71

S_Sky_Guide_TEXT_3ed_03.indd 71

7/5/08 11:33:17 AM

Chart 13 0 Hours to 3 Hours RA 0 to 55 degrees Dec

The most sig­nif­i­cant con­stel­la­tions in this part of the sky are a pair of zodiac signs, Pisces the Fish and Aries the Ram. Pisces, which has no bright stars, is com­monly drawn as a pair of fish with their tails tied together with long strings, swim­ming in oppo­site direc­tions. Looking north, it lies just above (south) and to the east of the Great Square of Pegasus (see Chart 20). The bright­est star, in the south-east corner, marks the knot joining the two strings. Aries, next door to the east, pos­sesses two bright­ish stars, close together and easily rec­og­nis­able. The brighter of the two is Hamal. Behind the con­stel­la­tion lies the story of the magical flying ram which rescued two chil­dren from their wicked step­mother, and whose Golden Fleece, hanging in a sacred grove in far away Colchis, lured Jason and the Argonauts in a per­i­lous quest in the years before the Trojan War. Above (south of) Aries, a pen­ta­gon of stars marks the head of Cetus the Sea Monster. In our present epoch, the Sun crosses the celes­tial equator going north and reaches a point among the western stars of Pisces around 21 March. The entry of the Sun into Pisces there­fore marks the north­ern vernal equinox (the autumn equinox for the Southern Hemisphere). Two thou­sand years ago this event occurred further east, with the Sun enter­ing Aries. The change since that time results from the pre­ces­sion of the equi­noxes. Tradition dies hard. The vernal equinox is still often called the First Point of Aries, and is marked by the old astro­ log­i­cal symbol for Aries. The com­pil­ers of horo­scopes con­tinue to insist that Aries is the sign for people born in the month com­menc­ing 21 March. The meteor shower known as the Arietids emerges from a point in the south­ern part of Aries (about 10 degrees above and to the left of the Pleiades) in the first two weeks of June, peaking on 7 June. North of (below) Aries and Pisces and the small con­stel­la­tion Triangulum, lines of bright­ish stars mark the where­ abouts of Andromeda the Woman Chained. The west­ern­most and bright­est star, Alpheratz, marks the maiden’s head and forms part of the Great Square of Pegasus (see Chart 20). Beta and Gamma Andromedae carry the line north-east towards the horizon, lying about 10 degrees apart. The con­stel­la­tion recalls the legend of the prin­cess chained to a rock in atone­ment for a boast made by her mother about her (Andromeda’s) beauty and rescued from a sea monster by Perseus. Most of the char­ac­ters in this tale are in the sky around about: Cetus the Sea Monster to the south (see Chart 5), and, further north, the maiden’s parents Cepheus and Cassiopeia. Her rescuer is next door on the eastern side (Chart 14). The con­stel­la­tion is notable for the pres­ence within it of the nearest and bright­est of the exter­nal gal­ax­ies, N224, com­monly called the Andromeda Galaxy or M31. This near twin of our Milky Way system lies about two million light years distant and is found about 6 degrees below and to the left of Beta Andromedae. Six times wider than the Full Moon, and with an inte­grated mag­ni­tude of 3.5, the nebula appears as a faint smudge to the naked eye on a dark night, and is a good target for binoc­u­lars and small tele­scopes. Three other members of our ‘local group’ of gal­ax­ies lie nearby in the sky, all fainter than M31 to our eyes. N221 (M32, mag­ni­tude 8.2) and N205 (M110, mag­ni­tude 8.0) are close to M31. More prom­i­nent is N598 (M33, mag­ni­tude 5.7 and twice the size of the Full Moon), about 10 degrees to the south-east (above and to the right) in Triangulum. The region has other sights worth looking for with binoc­u­lars. About 5 degrees south of Gamma Andromedae (close to the border with Triangulum) lies the open cluster N752 (diameter 50, mag­ni­tude 5.8). Gamma Andromedae is itself double (mag­ni­tudes 2.3, 4.8, yel­low­ish and bluish, 10 seconds apart).

­­72

S_Sky_Guide_TEXT_3ed_03.indd 72

7/5/08 11:33:18 AM

0h

5

1h

2h

3h

ERIDANUS D

XZ

0°

M77

0°

Alrescha

A

X

L

G

CETUS

TX

N

M

I

Menkar

Z

W

D

E

O

X

X

L

M

PISCES

LIP

O

R

Y Y



+20°

Mesartim

C

Y

C

Sheratan

H

Z

U

ARIES

G H K L

T

D

+30°

Z

+20°

T

A

14

6

M33

Mirach

S

R Q

M

N

U

185

X

CASSIOPEIA

4

A

L Shedir

S 7789

23

0

h

h

1499 California Nebula

B

M43

X

Algol

E

PERSEUS

+40°

N

51

Q

J

N

R

7

891

M A

H

1

h

MAGNITUDES

D 48

Mirphak

M

G

Q 457

Y

A

T

Z

S

I

M76

LACERTA

Menkib

1342

K

O

147

R

W

J

P

Y

Atik

Z

W

Almaak

W

X

I

L

17

G C

K

O

16 1023

M31 Andromeda Galaxy

O

+30°

R

T

M110

7662

925

752

R M32

G D B

ANDROMEDA

TAURUS

TRIANGULUM

E B

4

D

S

P

5

M

Hamal

41

A

6

R RZ

A

E

Alpheratz

+50°

5

U

PEGASUS

+40°

P

Q

B

RR

J

Y

20

S

I TV

T

TIC

M74

G

J

X +10°

EC

H

Algenib

O

X

P

+10°

70

K

A

N

869

J

2

h

884 Double Cluster

H

3

L

1545

1

b

1528

CAMELOPARDALIS

b2

+50°

4

h

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­73

S_Sky_Guide_TEXT_3ed_03.indd 73

7/5/08 11:33:19 AM

Chart 14 3 Hours to 6 Hours RA 0 to 55 degrees Dec

The north­ern parts of this stretch of sky are filled with the stars of Perseus, the hero who rescued Andromeda, and of Auriga the Charioteer. Old star pic­tures of the latter also show a goat, which is marked by the first mag­ni­tude star Capella (sixth in order of bright­ness among the stars). The name means ‘little goat’. Though bright, this star is elusive from south­ern lat­i­tudes; from most centres of pop­u­la­tion it rises barely 10 degrees above the north­ern horizon. Perseus has no bright stars. It does boast the fifth mag­ni­tude California Nebula (N1499) (the shape gives the name), which lies near 4 hr, 36 deg. Three degrees by one, it is rated mag­ni­tude 5. Ten degrees to the west and a little lower in the sky is the famous eclips­ing var­i­able star Algol (Beta Persei) that changes mag­ni­tude from 2 to 3.5 and back every three days. Algol, dubbed ‘the devil star’, is often shown on maps as marking the eye of the snake-haired monster Medusa, whose severed head Perseus is car­ry­ing. Alpha Persei, some 8 degrees further north, is sur­rounded by a large, bright, open cluster (Melotte 20). Higher in the sky lies one of the great zodiac signs, Taurus the Bull. It is com­monly depicted as rushing at nearby Orion the Hunter, which lies to the south-east (above and to the right). Orion is defend­ing himself with a club (see Chart 6). The Bull is among the most ancient of the star signs, dating back to at least Babylonian times 4000 years ago. Then it hosted the vernal equinox that now lies to the west in Pisces. Some sources iden­tify Taurus with the Cretan Bull tamed by Hercules, others with the dis­guise used by Zeus to seduce Europa, others still with the fire-breathing brazenhoofed bulls Jason had to tame on his route to the Golden Fleece. Though only the front half of the Bull is shown (as if it was coming out of water), Taurus has some great sights. Marking the shoul­der of the Bull, and the first stars to appear as the con­stel­la­tion rises, are the Pleiades or the Seven Sisters (M45). Four times the diam­e­ter of the Full Moon, this open cluster of young, hot, blue stars is a superb spec­ ta­cle even with the naked eye. On clear dark nights keen eyes will find eight or even ten to be naked-eye objects. Binoculars or a small tele­scope will reveal 30 or more stars. The bright­est is Alcyone at mag­ni­tude 2.9. The ear­li­est ref­er­ences to the cluster are from China more than 4000 years ago. Following the Pleiades across the sky (its name means as much) is the red giant star Aldebaran, which appro­pri­ately marks the eye of the Bull. This was one of the Royal Stars of ancient Persia, along with Regulus, Antares and Fomalhaut. These stars were the markers of the seasons as they lay then. From our point of view Aldebaran is super­im­posed on a more distant V-shaped star cluster known as the Hyades. (At one time, the whole cluster was called Aldebaran.) One hundred and fifty light years distant, this is the nearest of the major open clus­ters. Two of the stars in the Hyades are wide doubles, easily resolved with the naked eye or with binoc­u­lars: Theta Tauri (mag­ni­tudes 3.4 and 3.8, sep­ar­a­tion 5.6) and Sigma Tauri (mag­ni­tudes 4.7, 5.1, sep­ar­a­tion 7.3). Both the Hyades and the Pleiades have mytho­log­i­cal asso­ci­a­tions. In one tra­di­tion, they rep­re­sent two groups of sisters, all daugh­ters of Atlas but with dif­fer­ent mothers. Both were placed by Zeus among the stars; the Hyades as a reward for nursing one of the god’s chil­dren, the Pleiades as a pro­tec­tion against the amorous advances of Orion. The rising and setting of the Hyades and Pleiades were tra­di­tion­ally asso­ciated with rain. Filling out the con­stel­la­tion to the east are stars delin­eat­ing the horns of the beast, with Beta Tauri (Alnath, the ‘butting one’) making the tip of the north­ern horn. Close to the other tip you can find the Crab Nebula (N1952 or M1). This nebula is the remnant of a super­nova seen by Chinese astron­o­mers in 1056. One fifth the width of the Full Moon, it is rated mag­ni­tude 8. One of the year’s lesser meteor showers, the Taurids, emerges from two points in the night sky above the Pleiades over the month fol­low­ing 25 October, with a peak around 7 November. It is asso­ciated with Comet Enke and may produce about 12 meteors an hour.

­­74

S_Sky_Guide_TEXT_3ed_03.indd 74

7/5/08 11:33:20 AM

3h

6

4h

ERI

5h

0°

P

M77

D

P

K

G

A

0°

P

Bellatrix

N

CETUS

M

O

P 88

M L

+10°

71

G Hyades

S

D  ECLIPTIC

P

R Z

M

T 23 17 19,20 M45 Pleiades

ARIES

13

K U

N

119

Z

I M1

C

PERSEUS

W

RT

Z

Y

S

Y

I

D

Y

A

b1

L

Y Y

1528 7

Y

LYNX

R

G

CAMELOPARDALIS

J

Y Y

O

b2

+40°

Y

Y

Menkalinan

P

M

Mirphak

T

B

A

1545

51

21

D

X

+50°

H

M76

2

3

h

4

h

h

MAGNITUDES

4

UU

R PU

48

Q

5

Q

Q

N

T

H

Capella

ANDROMEDA

6

U

AURIGA

L

N

W

CAS

S

M

K

G

+50°

WW

2281

M43

891

Almaak

M36

M38

W

E +40°

+30°

M37

J

Menkib

E

Algol

E

K

58

B

Mebsuta

C

I

1023 752

15

GEMINI

B

1499 California Nebula

1342

+20°

M

H

M35

Alnath

Z

17

16

N TV Propus

Atik

TRIANGULUM

R

C

TAURUS

AR

B

U

1

1746

Y

R

C

Crab Nebula

J

X

X BL

6

G 925 D

+10° 2169

T

H Alcyone

O +30°

ORION

27 BU

41

MON

M

HU

37

+20°

T

J L

Meissa

O

S S Q  A Aldebaran D E 1647

W

D

RZ

Betelgeuse

O

R

8

A J

1662

90

5

32

G

P

X

L

W

P

N

V M78

R Y

Menkar

O

Alnilam

Mintaka

W

6h

2024

D

10

Z Alnitak

E

ERI

5

6

h

7

h

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­75

S_Sky_Guide_TEXT_3ed_03.indd 75

7/5/08 11:33:22 AM

Chart 15 6 Hours to 9 Hours RA 0 to 55 degrees Dec

The Milky Way cuts through the south-west corner of this area of night sky, cross­ing among other things the feet of Gemini the Heavenly Twins. The Twins’ feet are close to the head of Orion the Hunter, most of which lies on the other side of the Milky Way. At the north-eastern end of this roughly rec­tan­gu­lar con­stel­la­tion, the heads of the pair are marked by the bright stars Castor and Pollux. Like so many star groups, the Twins are upside down when viewed from the Southern Hemisphere. Though listed as Alpha Geminorum, Castor is cur­rently fainter than Pollux, indi­cat­ing that it has waned or Pollux waxed in bright­ness in recent cen­tu­ries. Castor looks like a single star to the unaided eye, but it is actu­ally six stars in close asso­ci­a­tion, all born long ago from the same cloud of gas. A small tele­scope will divide Castor in two. A pair of white stars, mag­ni­tudes 1.9 and 2.9, lie only 4 seconds of arc apart, and circle each other every 400 years. Castor was in fact the first pair of stars known to be orbit­ing each other, noted by William Herschel in 1803. Each com­po­nent star is a very close double, and other stars also form part of the action. The star names are also the names of the heroes. In Greek legend, Castor and Pollux were sons of Leda, Queen of Sparta, and broth­ers to Helen of Troy. Pollux (or Polydeuces), being the son of Zeus (who seduced Leda in the guise of a swan), was immor­tal and was famed as a boxer. Castor, a famous horse­man, was the son of a mortal. Both were voy­ag­ers with Jason on the Argo in search of the Golden Fleece. At the western end of Gemini, at 6 hours of right ascen­sion, the eclip­tic reaches its maximum dis­tance north of the celes­tial equator. This point on the celes­tial sphere there­fore marks the (north­ern) summer sol­stice, reached by the Sun around 21 June. This is the short­est day of the year (winter sol­stice) south of the equator. The Geminids, one of the con­sis­tent per­form­ers among the meteor showers, emerges from the night sky close to Castor from 7 to 15 December, with a peak around 13 December. Under the right con­di­tions, you may see 50 meteors an hour. Gemini too boasts a bright­ish cluster, lying in front of the Milky Way at the south-western end of the con­stel­ la­tion (near 6 hr 10, 24 deg). N2168 (M35) is the size of the Full Moon and is rated at mag­ni­tude 5. East of Gemini lies another zodiac con­stel­la­tion, Cancer the Crab. Cancer is bereft of bright or even bright­ish stars. Legends suggest that such was its fate, having been crushed as pun­ish­ment for biting the heel of Hercules as he was bat­tling with the Hydra. Such stars as there are make up a three-pointed figure centred on Gamma Canceri that lies on the ­ecliptic. Cancer’s main offer­ing to sky­watch­ers is Praesepe or the Beehive Cluster (N2632, M44), which lies a few degrees north-west of Gamma Canceri. At mag­ni­tude 3 and diam­e­ter three times that of the Full Moon, it is no match for the Pleiades, but is well worth a look through binoc­u­lars, which will easily reveal 15 or so stars (Galileo was the first to do this). Lying only 450 light years away, the Beehive is close as open clus­ters go. The old name for the Beehive is ‘the Manger’, which served as food for a pair of donkeys. These are marked by the two nearest stars, Gamma and Delta, which bear formal names meaning the ‘the north­ern and south­ern donkeys’. A small cluster (N2682), still worth a Messier number (M67), lies south of (above) the Beehive, a few degrees west of Alpha Canceri. Two thou­sand years ago, the summer sol­stice now found in Gemini lay in Cancer. This fact per­sists in the name ‘Tropic of Cancer’ for the imag­i­nary line around the Earth linking all loca­tions at which the Sun is over­head at noon on 21 June. Consistency would seem to require a change in name to ‘Tropic of Gemini’, but that is now unlikely. In 600 years it would need to be changed again. Monoceros, Canis Minor and Hydra border Cancer and Gemini to the south. To the north we find some faint stars of Auriga and Lynx, and a sniff of Ursa Major the Great Bear.

­­76

S_Sky_Guide_TEXT_3ed_03.indd 76

7/5/08 11:33:22 AM

Horsehead Nebula

I.434

S

E

6h

7

7h

Z

2024

Alnilam

D

ORION W

B E

13 2264

HYDRA

14

S

S

Q

D

R

G

W

Z

E

Gomeisa

B

M

J

J

L

Meissa

6

R

X 2169

X

N

BL

Alhena

G

L

BQ

Z

GEMINI Mekbuda

N 119

C

Z

+20°

U

Propus

C

TV

H

2392

Wasat

W

Mebsuta

W U

TAURUS

I

14 K

T

RT

B

R

WW

Q

C

Asellus Borealis

+20°

X

U

2903

Alterf

N

L

16

K  R R

I

LEO T

A Castor S

P

S

RS

S

+30°

2683

Q

U

S

UU

A

AURIGA

R B

PU

Menkalinan

LEO MINOR 10 UMa

Y

31

+40° Y

LYNX

A Capella

10

Y

Y

P

E

38

2281

Y

L

R

Y

Y

N

T

H

Z

Asellus Australis

J J

C

C

G

D

M36 M38

M

U

Y

J

Pollux

S

O

M37

J

AR

B

E

M44

Praesepe

L

E

Alnath

H

M

P

X

Q

K

M35

+30°

IC

ECLIPT

D

R

M

1

Crab Nebula M1

Z

+10°

Acubens

O O

CANCER

W

K

A

M67

30

+40°

0°

H

A

H

MONOCEROS

Betelgeuse

BC

Procyon

Rosette Nebula 2237 T

A

D

CANIS MINOR

2244 8

Z

D

10

+10°

9h

2301

M78

0°

8h

D

Alnitak

21

Y

Y

Talitha

I

K

URSA MAJOR

O 15

2841

Q

26

D +50° 1545

PERSEUS

7

X

CAM 5

CAM 6

h

RR

h

7

h

MAGNITUDES

6

5

4

+50°

J

15

8

h

9

10

h

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­77

S_Sky_Guide_TEXT_3ed_03.indd 77

7/5/08 11:33:24 AM

Chart 16 9 Hours to 12 Hours RA 0 to 55 degrees Dec

This stretch of sky belongs to Leo the Lion. Allowing for the fact that the con­stel­la­tion is upside-down to Southern Hemisphere viewers, not a lot of imag­i­na­tion is needed to discern a lion among the stars. A hooked line of stars at the western end of the group pro­files the beast’s head and neck, ending with the first mag­ni­tude star Regulus to mark a front paw (or perhaps the lion’s heart). A tri­an­gle of stars two fists width to the east marks the rump and tail. The bright­est of those stars is Denebola, that name coming from the Greek for ‘tail’. Leo is gen­er­ally held to rep­re­sent the Nemean Lion, slain by the mighty Hercules of Greek and Roman legend as one of his Twelve Labours, but there are, as usual, other pos­sibil­ities. The asso­ci­a­tion of a lion with these stars is much older. Regulus was one of the Royal Stars of Persia, along with Aldebaran, Antares and Fomalhaut, since 4000 years ago it was home to the summer sol­stice now located in Gemini. Links between the Sun and Leo are there­fore very ancient and may explain the common and long-stand­ing link between the lion and royalty (such as the lion being the ‘king of beasts’). The name Regulus is derived from a word for ‘king’. Regulus lies just north of the eclip­tic. As a result, it is com­monly approached, or even occulted, by a planet. A close approach by Mars or Jupiter can be a spec­tac­u­lar sight. Gamma Leonis or Algieba, the second bright­est star in the hook, is a double, with a pair of yellow stars rated at mag­ni­tudes 2.3 and 3.5. With a sep­ar­a­tion of only 4 seconds of arc, a small tele­scope is needed to split them. R Leonis, 5 degrees west of Regulus, is a Mira-type var­i­able, swing­ing between mag­ni­tudes 4.4 and 11.3 every 312 days. Leo is the site of one of the more erratic meteor showers; the Leonids emerge from near Gamma Leonis around 15 to 20 November, peaking around 17 November, and have been noted for at least 1000 years. It is asso­ciated with Comet Temple 1 that last came by in 1866. The number of meteors increases to a peak every 33 years (1999 was a peak year). Beneath the belly of the Lion (that is, above it as it stands in the sky) lie a number of exter­nal gal­ax­ies, out­li­ers of the Virgo Cluster (see text to Chart 9). None is brighter than the eighth mag­ni­tude. The easiest to find are N3623 and N3627 (M65 and M66), which good binoc­u­lars will pick up as fuzzy spots on a dark night (near 11 hr 20, 12 deg.). A 100 mm tele­scope is needed to reveal their shapes. North of Leo lies the much smaller Leo Minor and then the stars of the major Northern Hemisphere con­stel­la­tion Ursa Major the Great Bear. These stars rise only 10 or 20 degrees at most above the north­ern horizon and the ­con­stel­la­tion is not easy to discern.

­­78

S_Sky_Guide_TEXT_3ed_03.indd 78

7/5/08 11:33:24 AM

9h

8

10h

11h

12h

B

A

I

T

U

Zaniah

3521

H

0° Q H

S

T

SEXTANS

HYDRA

R

Z

C

O K

A

M67

A

R

X

Acubens

X

M65

3348

O

+20°

G

M87 M84 M86

M99

Denebola

4435/38

M98

M88

Asellus Borealis

CANCER

N

U U

M100

60

Algieba

D

Zosma

L

Alterf

Z

E

Adhafera

+20°

COMA BERENICES

54 3344

M

K

M85

93

2903

X

Praesepe

G

L

H

D

E

4216

B

Q Chertan

IC IPT

Asellus Australis

M44

H

LEO

+10°

4371

L

EC

X

Q

M66

3628

Y

4365

O

I

M96

M105

P

O

P

W

M95

Regulus

N

M61

N

R

31

W

+10°

S

P

E

Rasalas

Mel 111 4494

15 C

J

R

I

J

R

T

LEO MINOR

X

S

N

46

S S

+30°

G

Alula Australis

+30°

21

4631

10

B

38

4214

CANIS VENATICI

Tania Australis 3184

L

10 UMa

M

Cor Carola A

W

Tania Borealis

B

4490

Y

+40°

Chara

ST 31

+40°

M94

4449

I

K

C

Y

Talitha

LYNX

M106 2841

URSA MAJOR

Q

TU

26

15

J 21

Owl Nebula M97

Merak

W

+50°

B

CG

8

9

h

h

10

h

MAGNITUDES

4

4559

Alula Borealis

R

A

2683

5

17 4565

RS

6

0°

Zavijava

VIRGO

VY

W

D

B

11

h

Phad

M109

G

M108

+50°

12

UMA

13

h

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­79

S_Sky_Guide_TEXT_3ed_03.indd 79

7/5/08 11:33:26 AM

Chart 17 12 Hours to 15 Hours RA 0 to 45 degrees Dec

This area of sky pos­sesses few bright stars other than Arcturus in Bootes. It is remote from the Milky Way, with the North Galactic Pole (NGP) to be found within the con­stel­la­tion Coma Berenices (near 12 hr 50, 27 deg.). The eclip­tic passes to the south, with Virgo the nearest zodiac con­stel­la­tion. Coma Berenices (Berenice’s Hair) and Canes Venatici (The Hunting Dogs) are largish but dull con­stel­la­tions. They are notable mostly for the numbers of gal­ax­ies within their borders. These con­tinue the cluster centred in the north­ern regions of Virgo, a cluster com­monly called the Virgo Cluster (see Chart 9). This con­tains many hun­dreds of spiral and ellip­ti­cal gal­ax­ies, located at dis­tances esti­mated at 40 to 60 million light years. Some of these may be glimpsed as fuzzy points of light in binoc­u­lars and small tele­scopes. The best start­ing point is with the mag­ni­tude 8.4 galaxy N4472 (M49) in Virgo (near 12 hr 30, 8 degrees). Many gal­ax­ies of mag­ni­tude 9 and fainter are scat­tered over the sky about 5 degrees north of M49, across the Virgo/Coma Berenices border. A few more lie at the north­ern end of Coma near the galac­tic pole. More gal­ax­ies still are widely scat­tered in Canes Venatici. Five degrees west of the Pole and near Gamma Coma Berenices we find the open cluster Melotte 111 (the Coma Cluster), which is both bright (inte­grated mag­ni­tude 1.8) and large (almost 5 degrees across). Bootes the Herdsman, lying to the east of the two star groups men­tioned earlier, is dom­i­nated by the orange giant star Arcturus, fourth bright­est in the sky (after Sirius, Canopus and Alpha Centauri). It weighs almost the same as our Sun, but is larger, brighter and cooler, all char­ac­ter­is­tics of a Sun-like star in old age. From Arcturus, marking the head of Bootes, an elon­gated pen­ta­gon of stars runs north-east towards Ursa Major the Great Bear. The two con­stel­la­tions can be linked in several ways. Bootes as Herdsman drives the Great Bear around the North Pole. In images in which the stars of Ursa Major become a plough or a wagon, Bootes is the Ploughman or Waggoner. From Arcturus (or more from ‘arktos’, the Greek for ‘bear’) we get our word ‘arctic’, for the region where the two bears (major and minor) are high in the night sky. The Quadrantids meteor shower, gen­er­ally the year’s bright­est, has its radiant in the north­ern part of Bootes, peaking around 3 January. The name comes from the now aban­doned con­stel­la­tion Quadrans Muralis (the Wall Quadrant), which used to occupy this part of the sky. For hunters after glob­u­lar clus­ters, binoc­u­lars will reveal M3 (N5272) in the south­ern realm of Canes Venatici (near 13 hr 40, 28 deg.), at mag­ni­tude 6.

­­80

S_Sky_Guide_TEXT_3ed_03.indd 80

7/5/08 11:33:26 AM

12h

G

H

U

9

13h

Porrima Zaniah

4753

14h

LIBRA

Z

0°

T

VIRGO B

4636

Zavijava

15h

0°

109

110

D

M61

M5

S R

P

N

4365

4526 4535

M49

5248

O

W

R

X

+10° 4216

B

E

M59 M58 M60 4371 M87 M86 M89 M84 M90 4435/38

M99 M98

Denebola

Vindemiatrix

+10° Z U

M88 M91

A

M100

T

M53

COMA BERENICES

93

LEO

M64

G

X

4725

4565

T

SERPENS CAPUT

W W

B

E

M3

4559

Izar

Y Alphekka

S

C

R

4214

A

Cor Caroli

+30°

D

Seginus R

Chara

M94

B

N



i

K Mizar Alioth

G

E

Z

X

Q

M101

Alcor

80

11

12

h

13

h

MAGNITUDES

14

h

15

+50°

DRACO

5866

Megrez

h

T

HERCULES

D

Owl Nebula M97

J

U

I

M109

+40°

C

H

URSA MAJOR

Phad

L

J

Alkaid

M106

C

+50°

M N

L

Whirlpool Galaxy M51 5195

K

Z

B

Nekkar

BOOTES

CANES VENATICI

TU

ST

CORONA BOREALIS

Alkalurops

M63

Y

Y

G

M 

4449

+40°

4

G

Nusakan

Q

N

5

18

A

H

A

Alula Borealis

6

B

O

4631

+30° Alula Australis X

W

T

FS

NGP

16

A

T

O

+20°

4494

Mel 111

Arcturus

Muphrid

M85

+20°

P

H

16

h

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­81

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Chart 18 15 Hours to 18 Hours RA 0 to 55 degrees Dec

There are no bright stars in this corner of the sky and no strik­ing con­stel­la­tions. Much of the sky is taken up with the scat­tered stars of Hercules, per­former of the famous Twelve Labours and voyager on the Argo with Jason in the quest for the Golden Fleece. On old star charts, Hercules is often shown with club and lion skin, kneel­ing with his foot on the head of Draco the Dragon, a far north­ern con­stel­la­tion. With a little imag­i­na­tion, the observer can recover the image of a man with great arms and legs from the scat­tered stars. Interestingly, for Southern Hemisphere viewers, Hercules is the right way up, unlike Ophiuchus just to the south (see Chart 10), which is head down for us. Its bright­est star, Rasalgethi (‘the Kneeler’s Head’) lies at the south­ern (upper) end of the con­stel­la­tion, within a few degrees of Rasalhague (‘the Serpent-Charmers Head’) in Ophiuchus. This is an indi­ca­tion of the lat­i­tude from which those who formed the con­stel­la­tions viewed the sky. Hercules is cer­tainly big, in the top half dozen con­stel­la­tions for size. These stars have been formed into the image of a hero since Babylonian times, 4000 or more years ago. In giving the stars to Hercules, the Greeks were merely con­ tin­u­ing an old tra­di­tion. The best binoc­u­lar or small tele­scope sight here is among the western stars of Hercules, a few degrees above Eta. N6205 (M13) is the bright­est glob­u­lar cluster in the north­ern sky, though at mag­ni­tude 5.7 and diam­e­ter 17 minutes of arc, it is no match for Omega Centauri or 47 Tucanae in the south. M13 con­tains some 300,000 stars in a space 100 light years across and lies about 22,000 light years away. The rest of the sky here con­tains the small con­stel­la­tion Corona Borealis the Northern Crown, with an inter­est­ing arc of small stars; the north­ern stars of Serpens Caput (the head of the serpent being wres­tled by Ophiuchus further south); and a bit of Bootes. In Ophiuchus itself, you can find I4665 about 10 degrees south of Alpha Ophiuchi (Rasalhague). This is a loose cluster worth seeking with binoc­u­lars, being mag­ni­tude 4.2 and twice the diam­e­ter of the Full Moon. One item of inter­est in this region is the loca­tion of the so-called Apex of the Sun’s Motion, the point in the heavens towards which the Sun appears to be moving as it circles the Galaxy. Measurements of the appar­ent move­ments of the stars suggest that this lies in the eastern part of Hercules, close to its boun­dary with Lyra the Harp.

­­82

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15h

10

16h

LIBRA

18h

S

0°

L

A

0°

68

G

S

E

VIRGO

H

SERPENS CAUDA

U

W

Y

M5

110

109

17h

Unukalhai

I.4665

OPHIUCHUS

L

67 70

B

Cebalrai

K 6572

I

D

72

I.4593

+10°

C

Z

T

P



T B  T T

T

T

O

A

J

U

T

G

X

G

U s

R

B

SERPENS CAPUT

+20°

Kornephoros

P

A

D

G

Alphekka

E

Y Izar

C

O

B

L

E

H

Q

CORONA BOREALIS P

R

X

S

u

N

K L

Alkalurops

A

M13

T

Z

M 

N

B

c

O

HERCULES

+30° N N

P R

H

M

G

X N

E

Z

N

R

D

+30°

19

M

U

I

Nusakan

S

Seginus

+20° 109

D

W

17

102

95

6210

LQ

W

A

Rasalgethi

HERCULES

K

K

T I

+10°

Rasalhague

W S

R

N

Q

M

S M92

BOOTES

+40°

I

L

R

Rastaban

B

16, 17

URSA MAJOR

+50°

K

I

DRACO

Q 5866

M101

14

15

h

Q

16

h

MAGNITUDES

5

4

G

Etamin

CYGNUS

M

Alrakis

h

6

+40°

OP

i

Alkaid

 D D

LYRA

T

M57

Ring Nebula

E 

XY

X

H

A

B

J U

CANES VENATICI

Z

Vega

g

C

Sheliak

K

J

Nekkar

6633

N X

17

h

Grumium

18

K

I

QR

+50°

19

h

h

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

­­83

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Chart 19 18 Hours to 21 Hours RA 0 to 55 degrees Dec

This is a spec­tac­u­lar stretch of sky, crossed by the Milky Way from south-west to north-east, and home to the three bright stars of the Winter Triangle (Deneb, Vega, Altair), so called because they are most prom­i­nent on early even­ings in winter in the South­ern Hemi­sphere (it is the Summer Triangle north of the equator). On the western side we find frag­ments of the heroes Hercules and Ophiuchus. A few small, dim con­stel­la­tions (Sagitta the Arrow, Vulpecula the Fox and Delphinus the Dolphin) take up further space. The ‘big three’ on the other hand are Lyra the Harp, Cygnus the Swan and Aquila the Eagle. For all its length in this region, the Milky Way appears divided, due to the pres­ence of a band of dust com­monly found in the spiral arms of gal­ax­ies. The con­stel­la­tion Cygnus is the form of a cross that evokes a swan flying south along the Milky Way, though the con­stel­la­tion has some­times been drawn as a hen. As a swan, its pos­sible asso­ci­a­tions include Leda, seduced by Zeus in the guise of a swan, so giving birth to the hero Pollux, one of the hea­venly twins. The long bar of the Northern Cross is made up of Beta, Eta, Gamma and Alpha Cygni, with Delta, Gamma and Epsilon as the cross bar. Deneb (‘the tail’) is the first mag­ni­tude star that brings up the rear of the swan. With dec­li­na­ tion 45 degrees, Deneb remains low in the north­ern sky for most centres of pop­u­la­tion south of the equator. Of the 20 or so bright­est stars as seen from Earth, Deneb is the most distant (nearly 2000 light years), and the star with the great­est intrin­sic bright­ness. An abso­lute mag­ni­tude of 8 makes it some 25,000 times brighter than our Sun. Several bright nebulae show up against the back­ground stars, notably the appro­pri­ately shaped North America Nebula (N7000), 5 degrees east of Deneb. This is rated mag­ni­tude 4 and covers more than 12 times the area of the Full Moon. As with Deneb, finding this nebula needs a clear north­ern horizon. The much larger but fainter and more elusive Veil Nebula (N6960) is some 15 degrees south of Deneb. This nebula, only mag­ni­tude 7 but 7 Moon diam­e­ters wide, is a super­nova remnant. To the west and a little higher in the sky lies Lyra the Harp, with one strik­ing star Vega (fifth in bright­ness in the sky). Imagination is cer­tainly needed here to find a harp among these stars! A degree or so away from Vega on the lower right, Epsilon Lyrae (a ‘double double’), is a good test for keen eyes. Its two fifth mag­ni­tude com­po­nents lie over 3 minutes of arc apart. Binoculars will confirm this, and a small tele­scope will reveal that each star is itself a double. Beta Lyrae, about 7 degrees south-east of Vega, is another star with sur­prises. It is a double (yellow-white and blue, first and eighth mag­ni­tudes) easily split in small tele­scopes. But the bright primary is an eclips­ing var­i­able, shift­ing from mag­ni­tude 3.3 to 4.3 every 13 days. Gamma Lyrae, a con­stant mag­ni­tude 3.2 nearby, can be used for ­com­par­i­son. One of the more elusive sights of Lyra is the well-known Ring Nebula (N6720, M57), a plan­e­tary nebula lying between Beta and Gamma. At mag­ni­tude 8.8 and little more than 1 minute of arc across, it is no easy target. A large tele­scope is needed to reveal its ring-like shape. Smaller but brighter than the Ring Nebula is N6853 (the Dumbbell Nebula, M27), in front of the Milky Way in Vulpecula (near 20 hr, 23 deg.). With mag­ni­tude 7.3, it is as bright as any plan­e­tary nebula in the sky, being only 1000 light years away. About 10 degrees south-west of the Dumbbell Nebula on the border with Sagitta is the dis­tinc­ tive open cluster dubbed the Coat-Hanger, more for­mally known as Collinder 399. Completing the Winter Triangle is Altair, the bright­est star in Aquila the Eagle. It lies much higher in the sky than Deneb and Vega and, unlike them, it has another bright­ish star (Gamma Aquilae) only a few degrees away. The pair form a dis­tinc­tive group­ing.

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18h

11

19h 59

0° G B

H

Q

Alya

6572

W

6709

Tarazed

W

Rasalhague

R E

B

SAGITTA A

111

Coll 399

110 109

G

U

M15

D G U

H

PEGASUS

Q M27

113

A

1

Dumbbell Nebula

+20°

13

VULPECULA B

L M

18

23

Ring Nebula

N

N M57 N B

J

HERCULES

41

L G

C

Sulafat

A

Q

P

M

R

H

XY

Q H

E 

61

6910

Etamin

K

Deneb

W

R

Q

7027

+40°

7000 North America Nebula

O

RT

PEG

S

X

A

O

I

I

N Pelican Nebula I.5067-70

CYGNUS

D

AF 6811

OP

B

T

G

+40°

Rastaban

U

M29

Sadr

R

G

T

L

P

LYRA

M92

+30°

E

6871

M

Z

DT

Veil Nebula

 D D

Z

Vega c

6992-95

52 6960

39

X

K

u

20

T

SU

Sheliak

+30°

31

6940

M56

O

X

2

6882/85

Albireo

D

+10°

M71

1

102

B

Z

D

Q

A

Z

U

G

I

S

D

EQUULEUS

K

E H

FF

95

J

Z

E

B

DELPHINUS

O P

+10° A

Altair

G

C

A

X

A

X

OPHIUCHUS

Kitalpha

T

U

R

72

E

B

Alshain

M

6633

I.4665

S

AQUILA

I.4756

Cebalrai

+20°

0°

AQUARIUS

D

70

67

21h 71

Q

N

SERPENS CAUDA

68

20h

R W

W

63

6826

M39

AR

Y

2

P

LACERTA

P

DRACO

5

4 7243 33

+50°

M Alrakis X

17

h

Grumium

18

h

19

h

MAGNITUDES

6

5

4

20

h

CEPHEUS 21

22

h

h

CEP

A

B

+50°

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

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Chart 20 21 Hours to 24 Hours RA 0 to 55 degrees Dec

Though not one of the more spec­tac­u­lar stretches of night sky, there are many things of inter­est here. The most obvious feature is a rough square of mod­er­ately bright stars known as the Great Square of Pegasus. The square, lying to the east of Cygnus the Swan, is large, some 15 degrees or one and a half fists wide in each direc­tion. Strictly speak­ing, only three of the four stars belong to Pegasus the Flying Horse. The north-east star (on the lower right) is now­a­days given to the con­stel­la­tion of Andromeda the Chained Maiden, in which it marks the head of the prin­cess (see Chart 13). However, its name Alpheratz (‘the navel of the horse’) indi­cates its former asso­ci­a­tion. Most people asso­ciate Pegasus with Perseus, the rescuer of Andromeda. However, legend gives the honour of riding Pegasus to Bellerophon, the hero noted for his fatal bold­ness in seeking to ride to heaven. The role of Perseus was in bring­ing the winged steed into being, since Pegasus was created from the blood of the mon­strous Medusa, slain by Perseus, falling into the sea. Unlike most north­ern con­stel­la­tions, Pegasus is upright when viewed from our part of the world. What is more, the stars do, with little imag­i­na­tion, suggest the front portion of a horse gal­lop­ing (or flying) to the west. From the top left-hand corner of the square a curved line of stars traces the horse’s head and neck. This begins with Alpha Pegasi (Markab for ‘saddle’) and ends at the orange super­giant star Enif (‘nose’). The latter is the brightest in the constel­lation, even though it is labelled only Epsilon Pegasi. Lines of stars from the lower left-hand star (Beta Pegasi or Scheat, meaning ‘upper arm’) mark out the horse’s front legs. A few degrees north-west of Enif lies the glob­u­lar cluster M15, 30,000 light years away. At mag­ni­tude 6.0 and diam­ e­ter 12 minutes of arc, this is larger and brighter than many. It shows up as a fuzzy patch in binoc­u­lars, and small tele­scopes show its bright core, though they cannot resolve indi­vid­ual stars. The rest of the sky here is not mem­or­able; frag­ments and edges of Andromeda and other nearby con­stel­la­tions, and the insig­nif­i­cant con­stel­la­tions Equuleus the Colt or Foal and Lacerta the Lizard. The nearest zodiac sign is Pisces the Fish, lying south-east (that is, above and to the right) of the Great Square.

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21h

Sadachbia

22h

G

Sadalmelik

71

P

AQUARIUS

0°

12

A

M2

23h

24h

H

Z

K

AQL N

Kitalpha

A

Q

EQUULEUS DELPHINUS

Enif

E

S Homam

G D

Z

PISCES

I

Q

E

K

W

R 55

X

M15

+10°

70

I

Markab

H

Q B

Z

A

D

Algenib

9

G

PEGASUS

G

A

1

U

J

+20°

TV

C

L

2

I

M

Sadalbari

+20°

U

T

K

VULPECULA

Y Scheat

19

31 6940

23

DT

52 6960

41

Matar

Z

6992-95

P

39

E

L

T 61

S S

M29

R

CYGNUS

N Sadr

6910

7000 North America Nebula

A Deneb

W

O

W

AR

K

LACERTA

2

P

7243

M

I

L

5 M39

63

O

R

ANDROMEDA

7662

11

X

M110

Y

4

147

B

Q

Y

20

21

h

Z

22

h

MAGNITUDES

5

4

CASSIOPEIA

E

CEPHEUS h

6

O

R

RW

I

+40°

P

185

X 6826

N

7

RT R

M32

M31 Andromeda Galaxy

A P

W

R

Q

O

6

7027 Pelican Nebula I.5067-70

+30°

PSC

P

1

6871

+40°

D

7331

T X

G

A

U

E

P

Alpheratz

H

P

Veil Nebula

+30°

13

B

O

M

T

+50°

0° ECLIPTIC

TX

Biham

B

+10°

G

B E

XZ

L

7789

D

23

h

S

L

R 0h

X

J

N

Z

+50°

1

h

PER

DEEPSKY OBJECTS

3

2

1

0

brighter

Double stars

Variable stars

Open star clusters

Globular star clusters

Planetary Nebulae

Diffuse nebulae

Galaxies

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7/5/08 11:33:34 AM

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Appendix A: Using binoculars and telescopes

Helping the eye References are made in this book to the use of binoc­u­lars or a small tele­scope to improve the view of the night sky. Such instru­ments do several things. •  They collect more light than does the naked eye (they have a greater light grasp) and so enable the user to see fainter and more distant objects. •  They magnify objects, making them seem larger. •  They can see finer detail (that is, they have greater reso­ lution). An ordi­nary pair of binoc­u­lars would be rated 10 by 50, which means mag­nifi­ca­tion 10 and with lenses 50 mm in diam­e­ter. Such binoc­u­lars will magnify objects 10 times, which is about the highest useful mag­nifi­ca­tion. Higher mag­ nifi­ca­tions amplify the inev­i­ta­ble shaking of hand-held binoc­ u­lars to an unac­cept­able degree. More impor­tantly, the 50 mm lenses will collect 50 times as much light as the unaided eye, making visible stars down to mag­ni­tude 10 or 11. This was about the light grasp of Galileo’s first tele­scope, though it mag­nified 30 times. With it, Galileo saw the moun­tains of the Moon, broke the Milky Way up into stars, con­firmed the phases of Venus and dis­cov­ered the moons of Jupiter. The brighter of the nebulae, both light and dark, will show up well with binoc­ul­ars and you can sep­ ar­ate many double stars. As for res­o­lu­tion, binoc­u­lars will discern details two or three arc seconds across, pro­vided seeing con­di­tions are reason­­ably steady. This com­pares with the 15 or 20 arc seconds achiev­able with the eye alone. Three arc seconds is about 1/600th the appar­ent diam­et­er of the Full Moon, which means an object about 6 km across at the dis­tance of the Moon.

The main problem with binoc­u­lars is holding them steady. Rest your arms on some­thing, like the top of a fence or the arms of a deck chair. Or lie on your back on a rug. As with naked-eye viewing, the darker the sky the better. Avoid moon­lit nights if pos­sible. Avoid street lights and house lights. Get away from the glare of the city to the bush or a beach or even a large sport­ing field. And give your eyes time to become dark-adapted. Half an hour makes a great dif­fer­ ence, and the longer you stay out the more you will see. If you want some light to read the maps in this book when you are under the stars, put red cel­lo­phane over your torch, or use a torch with an almost-flat battery, so that it gives a dim reddish light. Red light does not upset night vision.

On to a telescope The next step up is to a small (or small­ish) tele­scope, either a refrac­tor (with a large lens at the front to collect the light) or a reflec­tor (with a mirror at the lower end). Buying a tele­ scope is a complex matter and it is best to take expert advice at an astro­nom­i­cal supply store. For a certain aper­ture, a refrac­tor will in general give a brighter, clearer image, but a reflec­tor will be notice­ably cheaper. Above about 80 mm aper­ture, refrac­tors become very  expen­sive, but reflec­tors to 200 or 300 mm, or even more, are quite afford­able. A 200 mm tele­scope will collect over one thou­sand times as much light as the naked eye and will reveal stars down to the four­teenth mag­ni­tude. That light grasp will reveal even the elusive planet Pluto.

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Appendix B: Planet positions

The following table provides information on the positions of four of the five naked-eye planets and their relationships with the zodiac constellations, the Sun and each other over the years 2008 to 2017. The positions given are for the period around the start of each month. Most of the information in the table refers to the exterior planets (Mars, Jupiter and Saturn), the orbits of which lie outside that of the Earth. The table indicates in which zodiac constellation the planet can be found around the start of each month, the months in which it is retrograding (moving to the west), and the dates on which the planet comes into opposi­ tion (directly opposite the Sun in the sky and therefore cross­ ing the meridian at midnight) and reaches conjunction (passing behind the Sun and therefore undetectable) with the Sun. No information is supplied regarding the planet Mercury. Mercury moves so quickly against the background of the stars that information provided once a month is of little value. Mercury is also relatively faint and hard to detect. Somewhat similar considerations apply to Venus. Because its movement is relatively rapid, and because its brilliance

makes it generally unmistakable, information is not provided regarding its position on the zodiac. However, the table shows whether Venus is a morning star (visible before sunrise in the east) or an evening star (visible after sunset in the west). It also gives the date of its maximum elongation east (greatest height above the sunset) and its maximum elongation west (greatest height above the sunrise). Between these two dates, the table shows when the planet is in conjunction with the Sun (at which time the planet cannot be seen). Inferior con­ junction marks the transition from evening star to morning star, superior conjunction marks the reverse transition. The final column of the table provides information on conjunctions between the four planets listed, that is, the dates when the planets come close together in the sky (to be more precise, the dates on which they reach the same right ascen­ sion). While all of the conjunctions listed will occur, not all will be readily visible (to the naked eye at least). Some will occur when the planets involved are positioned in the morning sky before sunrise, rather than in the more-conven­ ient-to-view evening sky; others will take place when the planets lie too close to be Sun to be visible.

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Morning Morning Morning Morning Morning Sup Conj 09 Evening Evening Evening Evening Evening Evening

January February March April May June July August September October November December

Venus

Max. Elong East 14 Evening Inf Conj 27 Morning Morning Max. Elong West 05 Morning Morning Morning Morning Morning Morning

Month

January February March April May June July August September October November December

Planet positions 2009

Venus

Month

Planet positions 2008

Table 5. Planet positions 2008–2017

Sagittarius Sagittarius Capricornus Aquarius Pisces Pisces Aries Taurus Gemini Gemini Cancer Cancer

Mars

Taurus R Taurus R Taurus R Gemini Gemini Cancer Leo Leo Virgo Virgo Libra Conj Sun 05

Mars

Conj Sun 24 Capricornus Capricornus Capricornus Capricornus Capricornus Capricornus R Capricornus R Opp 14 Capricornus R Capricornus R Capricornus Capricornus

Jupiter

Sagittarius Sagittarius Sagittarius Sagittarius Sagittarius Sagittarius R Sagittarius R Opp 09 Sagittarius R Sagittarius R Sagittarius Sagittarius Sagittarius

Jupiter

Leo R Leo R Leo R Opp 08 Leo R Leo R Leo Leo Leo Conj Sun 17 Leo Leo Leo

Saturn

Leo R Leo R Opp 24 Leo R Leo R Leo R Leo Leo Leo Conj Sun 04 Leo Leo Leo

Saturn

Venus/Saturn 13

Venus/Mars 19

Venus/Mars 18

Mars/Jupiter 17

Conjunctions

Venus/Jupiter 01

Mars/Saturn 11 Venus/Saturn 13 Venus/Mars 11

Venus/Jupiter 01

Conjunctions

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Morning Sup Conj 11 Evening Evening Evening Evening Evening Max. Elong East 20

Evening Inf Conj 29 Morning Morning

January February March April May June July August

September October November December

Venus

Max. Elong West 08 Morning Morning Morning Morning

Morning Morning Sup Conj 16 Evening Evening Evening Evening

Month

January February March April May

June July August September October November December

Planet positions 2011

Venus

Month

Planet positions 2010

Aries Taurus Taurus Gemini Cancer Cancer Leo

Sagittarius Conj Sun 04 Aquarius Aquarius Pisces

Mars

Virgo Libra Scorpius Scorpius

Cancer R Opp 29 Cancer R Cancer R Cancer Cancer Cancer Leo Virgo

Mars

Pisces Aries Aries Aries Aries R Opp 29 Aries R Aries R

Aquarius Pisces Pisces Conj Sun 06 Pisces

Jupiter

Pisces R Opp 21 Aquarius R Aquarius R Aquarius R

Capricornus Conj Sun 28 Aquarius Aquarius Aquarius Aquarius Pisces Pisces

Jupiter

Virgo R Virgo Virgo Virgo Conj Sun 13 Virgo Virgo

Virgo Virgo R Virgo R Virgo R Opp 03 Virgo R

Saturn

Virgo Conj Sun 01 Virgo Virgo

Virgo Virgo R Virgo R Opp 22 Virgo R Virgo R Virgo R Virgo Virgo

Saturn

Venus/Saturn 30

Mars/Jupiter 01 Venus/Jupiter 11 Venus/Mars 22

Conjunctions

Mars/Saturn 01 Venus/Saturn 10 Venus/Mars 23 Venus/Mars 29

Venus/Jupiter 16

Conjunctions

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Evening Evening Max. Elong East 27 Evening Evening Inf Conj 06 Morning Max. Elong West 26 Morning Morning Morning Morning

January February March April May June July August September October November December

Venus

Morning Morning Sup Conj 28 Evening Evening Evening Evening Evening Evening Evening Max. Elong East 01 Evening

Month

January February March April May June July August September October November December

Planet positions 2013

Venus

Month

Planet positions 2012

Capricornus Capricornus Aquarius Conj Sun 18 Aries Aries Taurus Gemini Cancer Cancer Leo Leo

Mars

Leo Leo R Leo R Opp 03 Leo R Leo R Leo Leo Virgo Libra Libra Scorpius Sagittarius

Mars

Taurus R Taurus R Taurus Taurus Taurus Conj Sun 19 Taurus Gemini Gemini Gemini Gemini Gemini R

Jupiter

Aries R Aries Aries Aries Conj Sun 13 Taurus Taurus Taurus Taurus Taurus Taurus R Taurus R Opp 03

Jupiter

Libra Libra Libra R Libra R Opp 28 Libra R Libra R Libra R Libra Libra Libra Conj Sun 06 Libra

Saturn

Virgo Virgo R Virgo R Virgo R Opp 15 Virgo R Virgo R Virgo Virgo Virgo Conj Sun 25 Libra Libra

Saturn

Venus/Saturn 20

Mars/Jupiter 22

Venus/Mars 06 Venus/Jupiter 28

Conjunctions

Venus/Saturn 27

Mars/Saturn 17

Venus/Jupiter 15

Conjunctions

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Inf Conj 11 Morning Max. Elong West 22 Morning Morning Morning Morning Morning

Morning Sup Conj 25 Evening Evening

January February March April May June July August

September October November December

Venus

Evening Evening Evening Evening Evening Max. Elong East 06 Evening Inf Conj 15 Morning Max. Elong West 26

Morning Morning

Month

January February March April May June July August September October

November December

Planet positions 2015

Venus

Month

Planet positions 2014

Leo Virgo

Capricornus Aquarius Pisces Pisces Taurus Conj Sun 14 Gemini Gemini Cancer Leo

Mars

Libra Scorpius Sagittarius Sagittarius

Virgo Virgo Virgo R Virgo R Opp 08 Virgo R Virgo R Virgo Virgo

Mars

Leo Leo

Cancer R Cancer R Opp 6 Cancer R Cancer R Cancer Cancer Cancer Conj Sun 26 Leo Leo

Jupiter

Cancer Cancer Cancer Cancer

Gemini R Opp 5 Gemini R Gemini R Gemini Gemini Gemini Conj Sun 24 Cancer

Jupiter

Conj Sun 30 Scorpius

Libra Scorpius Scorpius Scorpius R Scorpius R Opp 23 Scorpius R Scorpius R Scorpius R Scorpius Scorpius

Saturn

Libra Libra Conj Sun 18 Libra

Libra Libra Libra R Libra R Libra R Opp 10 Libra R Libra R Libra R

Saturn

Mars/Jupiter 17 Venus/Jupiter 26 Venus/Mars 03

Venus/Jupiter 01, 31 Venus/Mars 29

Venus/Mars 21

Conjunctions

Venus/Saturn 13

Venus/Jupiter 18 Mars/Saturn 27

Conjunctions

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Morning Morning Morning Morning Morning Sup Conj 06 Evening Evening

Evening Evening Evening Evening

January February March April May June July August

September October November December

Max. Elong East 12 Evening Inf Conj 25 Morning Morning Max. Elong West 03 Morning Morning Morning Morning Morning Morning

January February March April May June July August September October November December

Aquarius Aquarius Pisces Aries Taurus Taurus Conj Sun 27 Gemini Gemini Leo Virgo Virgo

Mars

Scorpius Scorpius Sagittarius Capricornus

Virgo Libra Libra Scorpius R Scorpius R Opp 22 Libra R Libra Libra

Mars

Virgo Virgo Virgo R Virgo R Opp 07 Virgo R Virgo R Virgo Virgo Virgo Conj Sun 26 Libra Libra

Jupiter

Conj Sun 26 Virgo Virgo Virgo

Leo Leo R Leo R Leo R Opp 08 Leo R Leo Leo Leo

Jupiter

Scorpius Scorpius Scorpius Scorpius R Scorpius R Scorpius R Opp 15 Scorpius R Scorpius R Scorpius R Scorpius Scorpius Conj Sun 21

Saturn

Scorpius R Scorpius Scorpius Conj Sun 10

Scorpius Scorpius Scorpius Scorpius R Scorpius R Scorpius R Opp 03 Scorpius R Scorpius R

Saturn

Venus/Mars 05 Venus/Jupiter 13 Venus/Saturn 25

Conjunctions

Venus/Saturn 30

Mars/Saturn 25 Venus/Jupiter 27

Venus/Saturn 09

Conjunctions

Notes: R = retrograding, Opp = opposition, Sup Conj = superior conjunction, Inf Conj = inferior conjunction, Conj Sun = conjunction with the Sun, Max. Elong = maximum elongation

Venus

Month

Planet positions 2017

Venus

Month

Planet positions 2016

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Index

Absolute magnitude 7 Achernar (Alpha Eridani) 48 Acrux 52 Adhara (Epsilon Canis Majoris) 60 Alcyone (in Pleiades) 74 Aldebaran (Alpha Tauri) 74 Algieba (Gamma Leonis) 78 Algol (Beta Persei) 8, 74 Alnasl (Gamma Sagittarii) 68 Alnath (Beta Tauri) 74 Alphard (Alpha Hydrae) 62 Alpheratz (Alpha Andomedae) 72, 86 Altair (Alpha Aquilae) 68, 84 Andromeda Galaxy (M31) 72 Andromeda the Chained Maiden 72, 86 Antares (Alpha Scorpii) 6, 66 Antlia the Air Pump 62 Apex of the Sun’s Motion 82 Apparent magnitude 6 Apus the Bird of Paradise 52 Aquarius the Water-Carrier 70 Aquila the Eagle 68, 84 Ara the Altar 52 Arcturus (Alpha Bootis) 80 Argo Navis the Ship Argo 50 Aries the Ram 72 Asterisms 1 Astronomical twilight 12 Auriga the Charioteer 74 Beehive, The (Praesepe, M44) 18, 76 Bellatrix (Gamma Orionis) 58 Beta Ceti 56 Beta Lyrae 84 Betelgeuse (Alpha Orionis) 9, 58 Binoculars 89 Bootes the Herdsman 80 Caelum the Engraving Tool 48 California Nebula (N1499) 74 Cancer the Crab 76 Canes Venatici the Hunting Dogs 80 Canis Major the Great Dog 60 Canis Minor the Small Dog 60 Canopus (Alpha Carinae) 50 Capella (Alpha Aurigae) 74 Capricornus the Sea-Goat 70 Carina the Ship’s Keel 50 Castor (Alpha Geminorum) 76 Celestial equator 9 Celestial poles 9 Celestial sphere 9 Centaurus A 52 Centaurus the Centaur 52 Cepheid variables 8 Cetus the Sea Monster 56 Circinus the Compasses 52 Clouds of Magellan 48 Coal Sack, the 18, 52

Columba the Dove 58 Coma Berenices (Berenice’s Hair) 80 Coma Cluster (Melotte 111) 80 Comets 17 Conjunction of planet 16 Constellations 1 Constellations, table of brightest 2–3 Corona Borealis the Northern Crown 82 Corvus the Crow 64 Crab Nebula (M1) 74 Crater the Cup 62 Crossing the meridian 9 Crux the (Southern) Cross 52 Cygnus the Swan 84 Dark nebulae 18 Declination 12 Delphinus the Dolphin 84 Delta Aquarids meteor shower 70 Deneb (Alpha Cygni) 84 Denebola (Beta Leonis) 78 Distances in sky 8 Dorado the Swordfish 48 30 Doradus 48 Double stars 8 Draco the Dragon 82 Dunlop 18 (Iota Pictoris) 48 Dunlop 227 54 Eclipses of Moon 14 Eclipses of Sun 14 Ecliptic 12 Emission nebulae 18 Enif (Epsilon Pegasi) 86 Epsilon Lyrae 84 Equuleus the Colt 86 Eridanus the River 48, 58 Eta Aquarids meteor shower 70 Eta Carinae 50 Evening star 16 False Cross 50 First Point of Aries 72 Flamsteed numbers 6 Flare stars 9 Fomalhaut (Alpha Piscis Austrini) 70 Fornax the Furnace 56 Galactic equator 68 Galaxies N55 56 N205 (M110) 72 N221 (M32) 72 N224 (M31, Andromeda Galaxy) 72 N253 56 N598 (M33) 72 N3623 (M65) 78 N3627 (M66) 78 N4472 (M49) 64, 80 N4486 (M87) 64 N4594 (M104) 64 N5128 (Centaurus A) 52 N5236 (M83) 64 N6744 54 Galaxies 18, 18–19, 80 Gamma Aquilae 84 Gamma Canceri 76

Gamma Velorum 50 Gemini the Twins 76 Geminids meteor shower 76 Giant stars 7 Globular clusters 18 47 Tucanae 48 M3 (N5272) 80 M4 (N6121) 66 M13 (N6205) 82 M15 86 M22 (N6656) 68 N6752 54 NGC 362 48 Omega Centauri (N5139) 52 Great Square of Pegasus, the 72, 86 Grus the Crane 54, 70 Hadar (Beta Centauri) 52 Hamal (Alpha Arietes) 72 Helical rising 60 Helix Nebula 70 Hercules 82 Herschel 3670 48 Herschel 4330 50 Herschel 4332 50 Hipparchos 66 Horologium the Clock 48 Hyades 74 Hydra the Female Water Snake 60, 62, 64 Hydrus the Male Water Snake 48 I2391 (Omicron Velorum) 50 I2602 50 I4665 82 Indus the Indian 54 Inferior conjunction 16 Iota Pictoris (Dunlop 18) 48 Irregular variable stars 9 Jewel Box, the 18, 52 Jupiter 16 Kappa Crucis 52 Kaus Australis (Epsilon Sagittaurii) 68 Lacerta the Lizard 86 Large Magellanic Cloud 48 Leo the Lion 78 Leo Minor the Small Lion 78 Leonids meteor shower 78 Lepus the Hare 58 Libra the Scales 66 Light grasp 89 Light year 6 Lupus the Wolf 52 Lyra the Harp 84 M1 (Crab Nebula) 74 M3 (N5272) 80 M4 (NGC 6121) 66 M6 (Butterfly Cluster) 66 M7 (NGC 6475) 66 M8 (Lagoon Nebula) 68 M11 (Wild Duck Nebula) 68 M13 (NGC 6205) 82 M15 86 M16 (NGC 6611) 68 M17 (Swan Nebula) 68 M18 (N6613) 68 M20 (Trifid Nebula) 68 M21 (NGC 6531) 68

M22 (NGC 6656) 68 M24 68 M25 (I4725) 68 M27 (Dumbbell Nebula) 84 M31 (Andromeda Galaxy) 72 M32 (NGC 221) 72 M33 (NGC 598) 72 M35 (NGC 2168) 76 M41 (NGC 2287) 60 M42 (Orion Nebula) 58 M43 (NGC 1982) 58 M44 (Praesepe) 76 M45 (Pleiades) 74 M46 (NGC 2437) 60 M47 (NGC 2423) 60 M48 (NGC 2548) 60 M49 (NGC 4472) 64 M57 (Ring Nebula) 84 M65 (NGC 3623) 78 M66 (NGC 3627) 78 M67 (NGC 2682) 76 M83 (NGC 5236) 64 M87 (NGC 4486) 64 M104 (‘Sombrero Hat’ galaxy) 64 M110 (NGC 205) 72 Magellanic Clouds 48 Magnitude of stars 6 Manger, the (Praesepe) 76 Maria 14 Markab (Alpha Pegasi) 86 Mars 16 Melotte 20 74 Melotte 111 (Coma Cluster) 80 Menkar (Alpha Ceti) 56 Mensa the Table Mountain 48 Mercury 16 Messier catalogue 19 Meteor showers 17 Arietids 72 Delta Aquarids 70 Eta Aquarids 70 Geminids 76 Leonids 78 Orionids 58 Quadrantids 80 table of brightest 17 Taurids 74 Microscopium the Microscope 54 Milky Way, the 18 Mimosa (Beta Crucis) 52 Minor planets 17 Mira (Omicron Ceti) 56 Mirzam (Beta Canis Majoris) 60 Monoceros the Unicorn 60 Moon, main features of 14 Morning star 16 Multiple stars 8 Acrux 52 Adhara (Epsilon Canis Majoris) 60 Algeiba (Gamma Leonis) 78 Alpha Centauri 52 Beta Lyrae 84 Castor 76 Delta Orionis 58 Dunlop 227 54 Gamma Andromedae 72

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Gamma Velorum 50 Herschel 3670 48 Herschel 4330 50 Herschel 4332 50 Iota Orionis 58 Iota Pictoris (Dunlop 18) 48 k Puppis 60 Mu Crucis 52 Struve 1120 60 Struve 1121 60 Theta Eridani 56 Musca the Fly 52 N4472 (M49) 80 N5272 (M3) 80 naked-eye doubles Alpha Librae 66 Epsilon Lyrae 84 Sigma Tauri 74 Theta Tauri 74 Nebulae 18–19 California Nebula (N1499) 74 Coal Sack (dark) 52 Crab Nebula (M1) 74 Eta Carinae Nebula (N3372) 50 Keyhole Nebula (N3372) 50 Lagoon Nebula (M8) 68 Lambda Crucis 52 M43 (N1982) 58 North America Nebula (N7000) 84 Orion Nebula (N1976) 58 Rosette Nebula (N2237) 60 Swan Nebula (M17) 68 Tarantula Nebula (N2070) 48 Trifid Nebula (M20) 68 Veil Nebula (N6960) 84 Wild Duck Nebula (M11) 68 New General Catalogue 19 NGC 55 56 NGC 104 (47 Tucanae) 48 NGC 253 56 NGC 362 48 NGC 1360 56 NGC 1499 (California Nebula) 74 NGC 1952 (M1) 74 NGC 1976 (Orion Nebula) 58 NGC 1980 58 NGC 1981 58 NGC 1982 (M43) 58 NGC 2070 (Tarantula Nebula) 48 NGC 2168 (M35) 76 NGC 2237 (Rosette Nebula) 60 NGC 2287 60 NGC 2354 60 NGC 2362 60 NGC 2423 60 NGC 2437 60 NGC 2451 60 NGC 2548 60 NGC 2682 (M67) 76 NGC 3242 62 NGC 3372 (Eta Carinae Nebula) 50 NGC 3766 50 NGC 4472 64 NGC 4486 64

NGC 4594 64 NGC 4755 (Jewel Box Cluster) 52 NGC 5128 (Centaurus A) 52 NGC 5139 (Omega Centauri) 52   NGC 6205 (M13) 82 NGC 6231 66 NGC 6705 (M11) 68 NGC 6720 (Ring Nebula) 84 NGC 6744 54 NGC 6752 54 NGC 6853 (Dumbbell Nebula) 84 NGC 6960 (Veil Nebula) 84 NGC 7000 (North America Nebula) 84 NGC 7293 (Helix Nebula) 70 Norma the Set Square 52 North Galactic Pole 80 Northern Cross 84 Novae 9, 66 Occultation 16 Octans the Octant 54 Omega Centauri 18, 52 Omicron Velorum 50 Open clusters 17–18 Butterfly Cluster (M6) 66 Collinder 399 84 Coma Cluster (Melotte 111) 80 Hyades 74 I4665 66, 82 Jewel Box (N4755) 52 M7 (N6475) 66 M8 (N6613) 68 M16 (N6611) 68 M21 (N6531) 68 M24 (‘star cloud’) 68 M25 (I4725) 68 M35 (N2168) 76 M41 (N2287) 60 M46 (N2437) 60 M47 (N2423) 60 M48 (N2548) 60 M67 (N2682) 76 Melotte 20 (Alpha Persei) 74 N752 72 N1980 58 N1981 58 N2362 60 N2451 60 N3766 50 N6231 66 Omicron Velorum (I2391) 50 Pleiades (M45) 74 Praesepe (M44) 76 Theta Carinae (I2602) 50 Trapezium (Theta Orionis) 58 Trumpler 24 66 Ophiuchus the Serpent-Holder 66, 82 Opposition, planet at 15 Orion Nebula (M42, NGC 1976) 58 Orion the Hunter 58 Pavo the Peacock 54 Pegasus the Flying Horse 86 Perseus 74, 86

Phases of Moon 13 Phoenis the Phoenix 48 Pictor the Painter’s Easel 48 Pisces the Fish 72 Piscis Austrinus the Southern Fish 70 Planetary movements, table of 91–95 Planetary nebulae 18 Dumbbell Nebula 84 Helix Nebula (N7293) 70 N1360 56 N3132 62 N3242 62 Ring Nebula 84 Planets, identifying 16 Planets, movements of inner 16 Planets, movements of outer 14–16 Pleiades 18, 74 Pointers, the 52 Polaris 54 Pollux (Beta Geminorum) 76 Praesepe (Beehive Cluster, M44) 76 Precession of the Equinoxes 13, 66, 72 Procyon (Alpha Canis Minoris) 60 Proxima Centauri 8, 52 Puppis the Ship’s Poop 60 Pyxis the Ship’s Compass 60 Quarantids meteor shower 80 Rasalgethi (Alpha Herculi) 82 Rasalhague (Alpha Ophiuchi) 82 Reflection nebulae 18 Regulus (Alpha Leonis) 78 Resolution 89 Reticulum the Reticle 48 Retrograding of planet 14–15 Rigel (Beta Orionis) 58 Right ascension 12 Rigil Kent (Alpha Centauri) 52 Rosette Nebula 60 Royal Stars of Persia 70, 74, 78 Sagitta the Arrow 84 Sagittarius the Archer 68 Satellites 17 Saturn 16 Saucepan, the 58 Scheat (Beta Pegasi) 86 Scorpius the Scorpion 66 Sculptor the Sculptor’s Chisel 56 Scutum the Shield 68 Serpens Caput the Serpent’s Head 66 Serpens Cauda the Serpent’s Tail 66, 68 Sextans the Sextant 62 Shaula (Gamma Scorpii) 66 Sidereal time 21 Sigma Octantis 54 Sirius (Alpha Canis Majoris) 60 Small Magellanic Cloud 48 Soothis (Sirius) 60 South celestial pole 9 South Galactic Pole 56 Spica (Alpha Virginis) 64

Stars 1 Stars, table of brightest 7 Struve 1120 60 Struve 1121 60 Summer Solstice 76 Supergiant stars 7 Superior conjunction 16 Supernovas 18 Taurids meteor shower 74 Taurus the Bull 74 Teapot, the (in Sagittarius) 68 Telescopes 89 Telescopium the Telescope 54 Terminator 14 Theta Carinae 50 Theta Eridani 56 Theta Orionis 58 Trapezium, the 58 Triangulum 72 Triangulum Australe 52 Trifid Nebula 18, 68 Tropic of Cancer 76 Tropic of Capricorn 70 Trumpler 24 66 Tucana the Toucan 48, 54 47 Tucanae 18, 48 Ursa Major the Great Bear 78, 80 Variable stars 8 Mira-type Mira 56 R Car 50 R Hor 48 R Leo 78 R Lep 58 S Car 50 U Ori 58 Eclipsing Algol 74 Beta Lyrae 84 Semi-regular L2 Puppis 50 Vega (Alpha Lyrae) 84 Vela the Ship’s Sail 50 Venus 16 Vernal equinox 12, 72 Virgo Cluster 64, 80 Virgo the Young Maiden 64 Vulpecula the Fox 84 White dwarf stars 8 Wild Duck Nebula (M11) 68 Winter Triangle, the 84 Zodiac 13

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