’ R A C T I C A L S T R O N O M W ITH TH E U NAID ED EYE

' B Y 6 O T R M A T m ; REV . HEC O CPH ERSON

A . R . . M . , F. A S

E ER F H E SOC I ETE ASTRO NO I U E D E F RA N E B O T C ETC . M M M Q , ! ! ! A T H OR OF T H E RO A NC E O F O D ER N ASTRO NO Y ASTRO NO ERS U M M M , M ! ! ’ ! F TO-D A Y A C E NT U RY S P ROG RESS I AST O O Y O , R M N l N

R EV ISED ED ITIO N

fio n bo n a n h Qfibi n hnrgh

T . c. E. c. A C K LTD T NELSON SONS LTD J , . . , .

CONTENTS .

INTROD U CTORY

TH E NORTHERN STARS

THE STARS OF WINTER

TH E STARS OF SP RING

THE STARS OF SU M M ER

TH E STARS OF AU TU M N

. TTHE S OU THERN STARS

N ND L SU , M O O N , A P ANETS

ASTRONOM ICAL PHENOM ENA

B IB LI OGRAP HY

IND E!

P R ACTICAL A STR ONOM Y .

C A T H P ER I .

I N T R O D T O R U C Y .

WH EN we cast our eyes to the heavens on any clear and , by preference , moonless night , o ur attention is attracted by apparently i n o f o f numerable points light , all degrees of T brightness . hese are the stars , which in all ages have drawn to themselves the atten tion f o nk n . . . ma i d Mr E W . Maunder , in a previ ’ o us o f hi m volume t s series , has Shown how an s attention was first directed to the heavenly i o f bod es , and how the mere recognition the n th e phases of the Moon , the varyi g positions of plan ets a n d the season al changes Of the stars has developed stage by stag e into the science f o astronomy a s we know it at the present day . Perhaps o f all the sciences modern as tr o n o m i s - t y the most awe inspiring , the mos wonderful , the most instructive . The aver age man reads o f the marvels which th e o f telescope and spectroscope reveal , the L 6 PRACTICA ASTRONOMY .

a n d great depths spaces , the rapid velocities , n the eter al working of evolution , and he H e o r n o f wonders . has little no k owledge the methods used by the astronomers in ! ascertaini ng the a cts of the science ; and he is not familiar with the stars or conste lla tions . Let us suppose that there is something unusual in the astronomical world . The news ! papers are full o f the Opposition o f Mars . The average man has read about Mars and he s is anxious to e e the planet for himself . The almanacs tell hi m that it is in a certain con n sa stellatio , y , Virgo , and the newspapers repeat the statements of the almanacs . The would- b e Observer o f Mars is as puzzled as H e hi f ever . knows not ng o the constellation H e Vir go . does not know where to look for di d it , and even if he , he would probably be H e unable to recognise it . is paying the penalty for not having made himself a o qua i n t e d with what we may call the topog r a h f p y o the heavens . A gain , let us suppose that a bright comet is to be seen o r that a meteoric shower is expected from a certain constellation , say , Le - b e o . The would Observer is in the same position as in the case previously mentioned . Hi s ignorance o f the topography of the sky i s at the root Of his inability to see the comet or to witness the meteoric shower . INTRODUCTORY . 7

S O much fo r the utility of knowing the names o f the various stars and con stella tions ; but a knowledge of this kind is more N0 o n e than merely useful . can really enter in to what may be called the spirit o f astron o m h a n n h o w y without aving acquai tance , i n ever slight , with the planets and stars As di vidually . a contemporary astronomer has well remarked ' H OW great an interest is given to any Object by the fact that we know its name . Take some town children o ut into the country and se t them to gather wild flowers : h o w instantly they a sk their ! o f names . It is the same in the case the n stars . When in a clear i ght we consider the heavens and behold apparently co unt s o f le s points light , we are confused and over whelmed by the number o f the stars and n by the complexity o f their di stribution . O e star appears to be almost the same as a n di ff other , except for the erences in bright o ness , and we l ok away from the sky again with neither interest n o r curiosity . But if we learn that such and such a star is Al de b a r a n , and such and such is Sirius , and a n d such such a constellation is Orion , then o ur interest in the stars is aroused and as a result we are desirous of tracing out the star groups and o f identifying the stars themselves . ! -b e But , the would astronomer asks at 8 L PRACTICA ASTRONOMY . this time how is it possible for me to lea rn the names o f the stars and trace the outlines Of the constellations without bein g taught 7 Carlyle in his Old age lamented Why did not somebody tea ch me the constellations and make me at home in the starry heavens ? ! But in reality it is not necessary for anyone ta u h t to be g the constellations . It is best n lea r n for everyo e to them for himself . When the would- b e astronomer begins hi s task it may seem almost impossible of attain o f i n ment , and some the h ts which are given in astronomical books on ly make the task ffi n n di . more cult For i sta ce , when we are told to draw imaginary li nes through such and such stars in the Plough , and that these will lead us to such and such stars in Bootes and will form triangles a n d quadrilaterals with such and such stars in Draco , we feel A f o f . ba fled with the magnitude the task gain , o n some maps and guides to the heaven s there are represented what are known as the ! n O constellatio figures . n such maps we find the Plough represented by the figure of a bear covered with stars , Cygnus by a star O spangled swan , rion by a human figure o f dotted with stars . The stars all mag n i tude s are inserted and named , but they are confused and indi vidually lost thr ough the i n tro ducti o n o f the constellation figures . These INTRODUCTORY . 9

figures Of course are o f extreme interest to the o f s a n d historian a tronomy to the antiquarian .

' They throw a flood of light o n importan t questions connected with the beginn i ngs Of o n i n astronomical science , but star maps ten ded for the beginner who desires to obtain a knowledge of the topography of the heavens , u they are utterly o t Of place . The best method of acquiring a knowledge o f a n d the stars is to study them as they are , to obtain a kn owledge o f the most important constellations in the heavens whi ch it is ! i impossible to mistake . From th s it is com pa r a ti v e ly easy to trace out the other co n st e lla ti o n s ; to simplify thi s task by ex planation and direction is the aim o f the following pages . Once the observer has become famili ar with the various constellations and their seas onal changes a new charm is added to As hi s interest in the stars . an able astron o f n omer has remarked , the task learni g the i i stars has a charm Of ts o wn . The s lent watchers from heaven soon become each a ili fam ar friend , and to any imaginative mind the sense that he is treadi ng the same path a s that traversed by the first students Of ! n Nature will have a stra ge charm . — Our Pla ce in th e U ni v erse Before enter ing o n the task o f describing the topog 10 T AL ! PRAC IC ASTRONOMY . r a h o f n p y the heavens , it is ecessary to consider briefly o ur position in th e Universe and the bearing Of the position a n d motions o n of our planet the appearance of the heavens , o n o f and the apparent motions Sun , Moon , n pla ets and stars . We o n 8000 live the Earth , a globe almost di miles in ameter . This globe is not , as the li d ancient astronomers be eve , suspended in space . It is in ceaseless motion ; it turns o n - its axis once in twenty four hours , and in addi tion it revolves round the sun in 36 51 days . The mean di stance o f the Earth from th e so Sun is miles , the pathway traversed by our world i s about di I n miles in ameter . order to travel round hi r t s great orbit in a year , the Earth whi ls thr ough Space at the amazing rate Of eightee n miles in o n e second . i s But the Earth does not travel alone . It accompanied on i ts j ourney by it s faithful satellite the Moon . The Moon revolves round

- the Earth in a little over twenty seven days , at an average distance Of miles . Just o ur o f da as we get unit time , a y, from the o f o n ea r rotation the Earth its axis , and a y ’ from the Earth s revolution round the Sun , o ur m o n th we derive other unit , the , from the ’ Moon s revolution round the Earth . i s n o t The Earth , however , the only body 1 1 INTRODUCTORY .

n d o r b o f whi ch revolves rou the Sun . The day holds sway over a large system o f bodies — a n d planets , comets meteors . The five larger planets are very conspicuous a n d have — been known from prehistoric times Mercury a nd Venus within the orbit o f the Earth ; I d S . n a Mars , Jupiter and aturn without di n n tio there are two dista t planets , Uranus , a n d almost invisible to the unaided eye , so a n d n Neptune , completely ; ma y small n o f a n d pla ets , between the orbits Mars e n Jupit r , but i visible to the unaided eye n n di T o accou t Of their great stance . here are also numerous comets and their kindr ed di bo es , meteors , revolving round the Sun and com i ng within the reach o f human vision from time to time . S so The Solar ystem , far as we know at n l prese t , is a ittle under miles di o f n in ameter , the orbit Neptune bei g the h known boundary . In this system the Eart is merely o n e planet amon g others ; and it n fif is by o means the largest . It comes th in order of size , being much smaller than a n d Jupiter , Saturn , Uranus Neptune , and

Slightly larger than Venus , Mars and Mercury . Th e Sola r S s em —Th e n y t Sun , the ce tral o f body the Solar System , is a huge globe di about miles in ameter . In volume it is one and a quarter milli ons of times greater L 12 PRACTICA ASTRONOMY.

a n d i t s than that of the Earth , mass is times that of our planet . The Sun is a great o f e i n o cn globe gaseous matt r , at an almost l n e n ce i v a b y high temperature . The glowi g — — v eIOpe visible to u S the photosphere i s T merely the outer surface . his surface is diversified from time to time by the appear — ance of sun - spots great holes o r cavities in the photosphere . From these spots it has been ascertain ed that the Sun rotates on its axis in about twen ty- fiv e days ; a t least thi s ri is the period for the equato al regions , for the vast globe does not rotate as a whole .

The Spots are not always equally numerous . They increase and decrease in a period of about eleven years . This period is called ae the solar cycle , and is obeyed by the facul , o r o n bright spots the photosphere , and by the prom i nences o r red flames whi ch are projected from the chromosphere , a thin gaseous envelope surroundi ng the photo n sphere . The corona , the outermost appe d o f di age all , varies in shape accor ng to the di same period . In ad tion , the variations o f the magnetic needle and o f the aurora o n earth have a sim i lar period . The dis co v ery o f magnetic fields in sun - Spots by the American astron omer H ale gives us so me idea o f the nature of the connection . The Sun holds sway over a system of bodi es 13 INTRODUCTORY. di di o f varying size and con tion . We may : 1 n vide these into two classes ( ) the pla etary , 2 and ( ) the cometary bodies . The planets fall into three subdivisions ( 1 ) the inner planets ; 2 3 ( ) the minor planets , or asteroids ; and ( ) the

t . ou er planets In addition , two of the inner and the four oute r plan ets are centres o f sub o f o r ordinate systems one more satellites . di The inner planets are , in order of stance ,

Mercury , Venus , the Earth , and Mars . Our planet is slightly larger than Venus and con r l side a b y larger than Mars or Mercury . Venus and Mercur y have no satellites ; o ur Earth o n e— — two has the Moon and Mars has . Comparatively little is known Of Mercury and Venus . Mercury seems to be a barren , rocky world , and it is generally accepted amon g astronomers that its rotation is per

- formed in eighty eight days , the same period as is required for its revolution round the m i e x eri Sun . One he sphere , accordingly , p cn ce s everlasting day and the other per pe tua l night . Many astronomers accept a t o similar conclusion in regard Venus , but the n s evide ce is n o t o strong . The atmosphere o f - Venus is very thick and cloud laden , and

- very few Of its surface markings are known . o n o n i ts Mars , the other hand , rotates axis in about twenty-four hours thirty -seven i o f i s co n m nutes . The atmosphere Mars

15 INTRODUCTORY . led him to the conclusion that there is a very o f thin atmosphere , and that vegetation a o f low order still exists . But the existence ani mal life is highly improbable . The lunar rota tion is performed in exactly the same period as its revolution round the Earth . One hem isphere is continually turned to wards us , and the other side has never been seen . u 800 The asteroids , a group of abo t tiny planets , revolve between the orbits of Mars and 4 00 Jupiter . The largest , Ceres , is about miles i in d ameter ; the smallest are very minute . A e di very tiny ast roid , scovered by Max Wolf 1 1 8 f n 9 t o m . early in , has a diame er— o ly four iles The four outer planets Jupiter , Saturn , Ne tun e— Uranus , and p are very much larger than the Earth and its neighbouring worlds .

The largest , Jupiter , is nearly miles in All diameter . four seem to be in a condi o f tion great internal heat , and it is doubtful if solid surfaces exist below their heavy cloud laden atmospheres . Jupiter has nine satel — lites four large a n d five small Saturn ten — Uranus four ; and Ne ptun e e so far as is — n e di e o . i s known In ad tion , Saturn ncircled o f ! by a wonderful system rings , composed o f myriads o f tin y meteorites revolving S O closely together as to be indi vidually indis ti n ui sh a ble ur g from o world . A considerable number o f comets are kno wn 16 PRACITCAL ASTRONOMY .

g to be members of the Solar System , revolvin round the Sun in very elliptical orbits . These s comet are not solid bodies like the planets , o f but appear to be collections loose stones , u surrounded by gaseo s matter . Meteors , or n - shooti g stars , are believed to be the products o f the dissolution of cometary bodies . t Let us suppose tha the Solar System , whi ch is both absolutely and relatively o f so co - vast an extent , were extensive with the n —i n visible u iverse other words , let us imagine for the sake Of clearness that the Uni v erse I t were no larger than the Solar System . would be indeed a very large universe , much larger than we are able to comprehend . The Sun would rise and se t as at present ; it would ascend to its highest point in summer and descend to its lowest point in winter . The Moon would pass through i ts cycle of changes in its revolution round the Earth . The planets would make their periodical a p e a r a n ce s li n p , shining bril a tly on an inky black sk y . Usually there would be some object visible in this black sky o n moonless nights n r o e o two planets would probably be seen , but there would be even ings o n which the F r heavens would be absolutely black . o there would be no stars . Thus by imagining the heavens without stars , we are enabled at once to assign to the 1 INTRODUCTORY . 7

n i n stars their true positio the order Of nature . The stars are lumin aries far outside o f the S Solar ystem the stars , in fact , are not worlds in any way analogous to the planets they are themselves suns similar to the central body

‘ Of the S olar System . It is true that when we see a planet on the backgr ound o f stars ll it appears much more bri iant . Jupiter , for I hi i nstance , s nes many times more br ghtly o f than Sirius , the brightest the stars ; and yet Jupiter in comparison with even the faintest star which we se e twinkling in the f ni field o the telescope is utterly insig ficant . It belongs altogether to an inferior order o f f bodies ; it is merely the attendant o a star . Thus we se e that one effect o f the great di s tance of the stars is to make them seem very

insigni ficant bodi es . Another effect o f their di stance is that their motions are t o the ordinary observer a b so l o f lute y imperceptible . One the great truths Of modern astronomy is that the so - called fixed stars are in motion in various di r e c tions and with di fferent velocities ; but so great is their di stance that these motions can

only be noted after the lapse of many years , with the aid Of powerful in struments a n d H o r H e exact mea surements . Were omer siod o f o f J o b a to - or the author the Book live day , they would see the same constellations and 2 18 L PRACTICA ASTRONOMY .

a st rs with which they were familiar . They would behold apparently unchanged the bands o f Orion a n d the Pleiades a n d ! th e Bear with her train . f Thus to us the —stars are the background o the Solar System the setting to the dr ama o f An d the planetary motions . as such the f stars were treated o r many years . They were Observed mainly a s convenient reference points for the Observation Of the positions of the Moon and planets . Since the days Of a H Sir Willi m erschel , however , the stars have been observed and studied for their Own sake . The stars then are the di stant background

Of the Sola r System . Thus when we read in astronom i cal almanacs o r in the newspaper press that Mars is in Aries o r Jupiter is in Taurus , it is necessary for us to remember that seen from the Earth , Mars is in the same line o f vision as the stars in the constellation Aries ; that the constellation Taurus is the c ba kground against which Jupiter is seen . We must also bear in mind that the stars n o t a are a real background , but only an p o n e parent . The constellation Taurus , for n o t di instance , is a collection of bo es all at the same di stance from the Solar System . Some o f the stars in the constellation form co n connected groups and systems , but the stellation is not necessarily a uni ty . In 1 INTRODUCTORY . 9

f n di s o ther words , the stars are at dif ere t ta nces . Sirius , for instance , the brightest star in the sky , is much closer to the Earth n than Rigel in the neighbouri g constellation . di To The stars are at various stances . make this clear, a simple illustration may be

n . s sa give Two star , let us y of equal bright ness , appear close together in the heavens .

They may form a connected system , but not l t necessari y . One may be much closer o the

Solar System than the other , and they may appear close together merely because they happen to lie in the same lin e of vision . It is quite a mistake t o suppose that the brightest stars are necessarily the nearest . Sometimes

- so . Fo r they are , sometimes they are not o f instance , an insignificant star the fifth magni tude in the constellation Cygnus is nearer to the Earth than Sirius , the brightest sk star in the y . Di s n ce o f th e S s — ta tar . Something remains to be said Of the di stance and magn i f tude o the stars . We have seen that the diameter o f the Solar System is a little under

(five thousand million) miles . The principle o f the measurement o f star di stance has been explained by Mr . Maunder a n d in another volume of this series , it is only necessary to give o n e o r two examples o f the di f Th e n stances o the stars . earest star is 20 L PRACTICA ASTRONOMY .

only visible in the southern hemisphere . It is the brightest sta r o f the constellation Cen A a n d taurus and is known as lpha Centauri , the distance o f thi s o r b is about twenty- fiv e l f bil ions o miles . It is almost impossible to di d b e ' realise this vast stance , but an i ea may gained from consideration o f the fact that if di the stance from the Sun to Neptune , the di S most stant planet of the olar System , were 10 represented by feet , the nearest star would di be fourteen miles away . The great stance o f the stars may be better realised in another Of hi way . The rays light , w ch travel from n a n d the Moon to the Earth in a seco d a half , o f m i with a velocity les per second , cross the di ameter o f the Solar System in ui fo r eight hours . Four years are req red light to travel from the nearest star . Ma n i udes o f th e S r s — g t ta The stars , as we di have seen , are situated at all stances from t the Solar Sys em , and probably they are f Y e t ll o all Sizes . their apparent bri iance does not o n the whole depend o n di stan ce or

o n . size alone , but both One bright star may be comparatively near and of moderate i i m size , another may be very d stant and of di mense dimensions . The stars are vided into m a gn i tudes accordin g to their apparent brightness ; and si x magni tudes of stars a r e within reach Of the unaided eye . There are 2 INTRODUCTORY . 1 about twenty stars Of the first magnitude and f o f l sixty o the second . Some the conste la n tio s , as will be explained , are very rich in bright stars , others very poor . Th e brightest stars have proper names . Th us the brightest star of Cani s Maj or is n o f k own as Sirius , and the brightest star A Taurus is known as ldebaran . These proper names were given to the stars by the early A astronomers , Greek and rabian . When the stars came to be catalogued and charted it n di was ecessary to designate them in vidually . Accordingly the brighter stars i n each co n stel lation are known by the letters of the Greek A A alphabet . Thus ldebaran is also lpha A Tauri (literally lpha of Taurus , Tauri n A being the Latin ge itive) , Sirius is lpha n Ca is Maj ori s . When the Greek letters b e come exhausted , numbers are used . Th e Stella r U n iverse —Just as the Earth a n d the other plan ets form a system o f worlds n n d so revolvi g rou the Sun , the Sun and the other stars also form a con nected system o n a r e a much vaster scale . While the planets l o f di separated by mil ions miles , the stances between the indi vidual stars are to be reckoned by billions . Much in formation has been collected co n — cerning—indi vidual stars their di stances and masses a n d concerni ng double and variable

23 INTRODUCTORY .

o f s lae several thousands gaseou nebu ; but , i nevertheless , it appears to be strictly l mited ! S in extent . Like the Solar ystem , this greater Stellar System seems to be merely o n e amon g others! Recent research makes it probable that some of the isolated star- clusters and many o f ae the spiral nebul are external , though prob ably smaller and perhaps dependent , systems di i n plunged at vast stances space . It has s H been computed that the clu ter in ercules , o n e o f n is a t di so the earest , situated a stance great that light requires years to travel . We are confronted then with an ascendi n g o f — scale world systems . First Of all , we have — the little terr estrial system the Earth and Moon—and other satellite systems within the n l S greater Solar System seco d y , the olar Syste m i s merely o n e Of millions o f other n o f systems , compo ents the greater Stellar d S — System ; thir ly , the Stellar ystem vast , almost infinitely vast in exten t though it be — appears to be but o n e o f a number o f similar systems scattered throughout the infini te ex o to tent f space . The human mind is unable conceive this apparently endless profusion o f suns and systems and systems o f systems . We pause awe- stricken beforewhat Shelley a ce n tury ago called This in te rmin a ble wilde rn ess Of wo r s a o e me n t ld , t wh s im si y E e r v n so a in g fa n cy sta gg e r s . 24 L PRACTICA ASTRONOMY .

i n fin it — We are face to face with y the eternal , the illimitable , the unthinkable . In the words o f o f a ch e th the poet Richter , The Spirit man with thi s infinity for end is there none ! to the Universe Of God . Lo also there is ! no beginning .

A CH PTER II .

TH E NORTH ERN STARS .

’ TH E positions o f the stars in the sk y a r e sub — j ect to two periodi cal chan ges the hourly n change and the seasonal cha ge . The former is due to the rotation of the Earth o n its axis and the latter is due to its revolution roun d se e the Sun . Even the casual Observer can that the stars rise and se t like the Sun and that di fferent stars are visible at di fferent seasons . O wing to the rotation of the Earth o n its axis the entire star- sphere appears to move round o ur world once in twenty- four hours ; and owing to the revolution Of the Earth o r b round the Sun , the of day appears to move a mong the stars , or rather , the stars appear ri n to drift westward into the sunset , si g and settin g four minutes earlier each night . The Earth rotates o n an axis which is H 25 T E NORTHERN STARS . inclin ed to the plane o r level Of the terrestrial orbit round the S un by about sixty- seven e di d grees , and to the perpen cular by about

- twenty three degrees . The result is that some se t stars rise and like the Sun , others are never to be seen , while others again neither rise nor ! se t n , but seem to circle round a fixed poi t in the Sky , and are continually visible whenever sk the y is clear and the Sun absent . In a survey of the heavens , it is wise to commence wi th the stars whi ch are continually visible the circumpolar stars of the northern hemi

Sphere . Th e lo u h — P g . The axis o f the Earth points to a part Of the heavens very close to a bright star Of the second magnitude known as the i l Pole Star , wh ch remains practica ly stationary in the heavens . But the Pole Star is not the most suitable object from which to commence f a study o the circumpolar stars . There is no question that the large constellation o f Ur sa M a m o r —o r o f i , the Great Bear a part — it is the conspicuous object o f the northern heavens . N0 one can m i stake the seven stars w C ’ kno n variously as the Plough , harles s — — Wain and i n America the Dipper . These stars have been noted and Observed from the earliest ages ; they are referred to by H omer H d and esiod an in the Book of Job . Th e Plough is see n to best advanta ge in 26 AL PRACTIC ASTRONOMY . autumn , when it is due north and compara ti v ely low down in the heavens ; there can i then be no d fficulty in identifying the group. The northern heavens are not especially rich n n in bright stars , and in the autumn eve i gs the Plough is visible either slightly tilted to - o r i the north west , due north , slightly t lted - di to the north east , accor ng to the hour Of the night o r the time o f the season . For ’ ni o f instance , at ten O clock in the begin ng

‘ 6 0 8

— l . e P . FI G . Th lo ugh

di October the Plough is rectly north , a month later at the same hour it is slightly tilte d to the north - east but it is unnecessary here to mention the various days and hours o n whi ch di the Plough is to be seen in fferent positions . O nce the configur ation of the cons tellation i s th e i di ffi implanted in m nd , there will be no i n ut o . culty picking it , whatever its position th In e winter evenings , generally speaking , the Plough is in th e north- ea st ascending in E 2 TH NORTHERN STARS . 7

n As a the heave s . the hours p ss on during ni o r the same eve ng , as the season progresses at the same hour , the Plough rises higher and hi gher in the heavens until in Spring it is practically in the zeni th in the hours fitted for Observation . This is the season when it

di f n . is most ficult to recog ise the Plough If , li however , we are fami ar with it before , it is quite easy to i de n tifv the well-known figure hi sk gh in the y . In summer , the Plough is

- to be seen in the north west , descending as v n the season ad a ces . O n the whole it may safely be said that the a n autumn is the best se so for a beginner , who knows nothin g of the constellations and has n ever seen the Plough , to commence his di stu es . Obvious at all times , the Plough is absolutely unm i stakable in the autumn even n i gs . There are seven stars in the constella si x o f hi n tion , w ch are , roughly speaki g , Of d f the second magni tu e and o n e o the fourth . Proceedi ng from the front of the Ploughshare s dl de si backward to the han e, the stars are g n a te d by the first seven letters of the Greek —A E alphabet lpha , Beta , Gamma , Delta , p w silon , Zeta , and Eta . They are also kno n A A by rabic names . lpha is Dubhe , Beta ! is Merak , Gamma is Phecda , Delta is ! A ! Megrez , Epsilon is lioth , Zeta is ! ! Eta Al o r Mizar , and is kaid Benet 28 AL PRACTIC ASTRONOMY .

n a . sch Of these names , only the Sixth , i s e . Mizar , commonly us d Two o f the stars in the Plough call for special l mention , Delta and Zeta . Delta is general y believed to have been at one time o f the second ni o f mag tude , whereas it is now the fourth , so it would seem to have decreased in brilliance .

Zeta , generally known as Mizar , is a remark A able star . keen eye can detect the fact o r that it is double , rather that there is a faint i s companion star near . This little star known

A : as lcor , and in the binocular the two make a striking spectacle . With a moderate tele i s scope Mizar seen to be itself double . The Plough is only part o f the con stellation a co n s i cu Urs Maj or , but it is much the more p us n o part . The remaini g stars Of the con stellation are much fainter and much more di ff icult to trace . — Th e Po le Stan Alpha and Beta o f Ursa ! Maj or are known as The Pointers , because a straight lin e j oining these two stars points directly to the Pole Star . Once these two t o stars are known , it is impossible mistake n the Pole Star . It is noticeable as bei g the next conspicuous star in the line with the As Pointers . its name indicates , the Pole Star approximately marks the point in the ’ n heavens to which the Earth s axis poi ts .

To an Observer at the North Pole , the Pole HE T NORTHERN STARS . 29

Star would appear almost exactly overhead ;

to an Observer at the equator, it would seem r almost exactly on the horizon . In o u lati d o f tu es , the altitude the Pole Star above the horizon varies with the latitude o f the place di from which it is observed . To the or nary observer , the star seems stationary in the o n e un heavens , the point aro d which the other stars describe circles . In reality its position does n o t exactly coincide with the celestial Pole ; it actually describes a very ll sma circle , and there are several stars nearer l to the Pole , which are practica ly invisible — without the aid o f a bin ocular the chi ef o f M i i s these being Lambda of . Ursa inor , wh ch just visible to the unaided eye . The Pole Star is the chi ef star o f Ur sa M rim o r a n d A the Little Bear , is also known as lpha l Ursae Minoris . The conste lation Ursa Minor , like the more conspicuous Ursa Maj or , has seven principal stars . Proceeding in a curve from the Pole Star these are Delta , Epsilon ,

Zeta , and Beta while Gamma and Eta form a square with Beta a n d Zeta . Beta and Gamma are the only noticeable stars Of the constellation except the Pole Star . a ssi o ei a C p . O n ce the Plough and the o f Pole Star have been identified , the task learni ng the arrangement of the northern stars is much simplified . If we keep the

THE NORTHERN STARS . 31 A d D . a n elta , and Epsilon Beta , lpha , Gamma o f a n d a are the second magnitude , Delt and

o f . Epsilon are the third Kappa , though — — faint Of the fourth magnitude is prominent f by reason o its position . It forms a trapezium A a n d . A i with Beta , lpha , Gamma nother fa nt star whi ch is easily identified by reas on o f its i position is Iota , wh ch is in a straight line with

Delta and Epsilon . The constellation is o n e o f the richest in the i t di ff heavens , and in this ers from its com

- panion star group , the Plough . Ursa Maj or is situated in a barren portion Of the sky . Cassiopeia is fully immersed in the stream o f

‘ k r the Mil y Way o Galaxy . The Milky Way i s o f - one the best known celestial phenomena . As Mr . Maunder has explained in a previous o f hi l volume t s series , the Mi ky Way is the ! f ! foundation o the celestial building . It - f is the ground plan o the Universe . It is nothing more nor less than the region o f the heavens in whi ch the stars are most closely d crowded together . To the unai ed eye it presents the appearance o f a belt Of milk y sk light across the y ; and in this belt , not at d o n e the broa est , but at of its brightest parts , i Of C the ch ef stars assiopeia are immersed .

To the observer with a binocular , Cassiopeia is a particularly interesting field for Observa tion . The star Gamma is the centre o f o n e 32 L T PRACTICA AS RONOMY . Of the most remarkable regions in the heavens in regard to the sym metrical arrangement of the stars it is also very crowded . The constellation is also famous in the history o f astronomy owing to the fact that the most brilliant temporary star which h a s been recorded shone o ut near Kappa in August 1 2 5 7 . This star was particularly studi ed by h o the famous astronomer Tycho Brahe , w , di d di r although he not scover it , Obse v ed it so patiently and systematically and left so complete an account o f its variations that it T h ’ ! has always been known as yc o s Star . 1 5 72 One evening in November the astronomer , o n n d n casti g his glance upwar s , was astou ded to notice the familiar appearance o f Cassiopeia completely changed by the presence o f a new and brilliant star whi ch far outshone the other stars in the constellation . When first seen by i Tycho it was as br ght as Jupiter , and when it reached its maximum it was equal to Venus n in brillia cy , being visible in full daylight . i e Stead ly d clining , it ceased to be visible to the unaided eye a year and a half after i ts appearance . a lla a e — C pe n d V g a. H aving identified the

Plough , the Pole Star and Cassiopeia , it is comparatively easy for the observer to find As a l the other important northern stars . u ready mentioned , the Plo gh and Cassiopeia THE NORTHERN STARS . 33

are o n opposite sides o f the Pole Star There o n o f are two stars , also opposite sides the d n Pole , which are useful gui ing stars not o ly for the northern heaven s but also for the stars se f which rise and t . On account o their A A brilliance , Capella ( lpha urigae) and Vega (Alpha Lyrae) cannot be mistaken ; a n d a l — — though these are a t least in Scotlan d cir cum o la r d p stars visible all the year roun , Aur iga and Lyr a cannot properly be described n as circumpolar co stellations . Capella is the prom i nent star of the first magnitude between

C . assiopeia and the Plough In the autumn , when the Plough is due north and Cassiopeia ni d n nearly in the ze th , Capella is ascen i g in - n the north east . In wi ter , when the Plough is ascen din g in the north- east and Cassiopeia - C l descending in the north west , apel a is to e i s o be seen almost overhead , while V ga pra

tically lost in the haze Of the horizon . In n Spri g , when the Plough is nearly overhead C i n C and assiopeia low down the north , apella is descendi n g in the n orth- west and Vega

- d . ascen ing in the north east In summer , when the Plough is descen di ng in the north west and Cassiopeia ascen di ng in the north C east , Vega is nearly overhead , while apella n is practica lly lost in the haze of the horizo . Vega and Capella will be more fully de scribed i n the chapters o n the summer and 3 34 L M PRACTICA ASTRONO Y . winter constellations respectively ; but it is essential that these two stars should be known soon after the Plough and Cassiopeia . — Ceph eus There are other two northern con stella ti o n s , less conspicuous than those men ti o n e d , which it is well to identify . These are Ce s D r l ph eu and a co . The former conste lation adj oins Cassiopeia . When Cassiopeia is low down in the north Cepheus is above Cassiopeia to the right , and practically immersed in the stream o f the Milky Way A The stars lpha , Beta , Iota and Zeta form - All a well marked trapezium . four are of the third magnitude . Within the trapezium and 18 o f nearly in the centre Xi Cephei , the fifth magnitude . Gamma Cephei forms a triangle with Iota and Beta ; it is Of the third mag n itude and comparatively close to the Pole A Star , with which it is in line . nother much r smaller triangle is fo med by Zeta , Epsilon — and Delta . Delta is a variable star the brightest o f the important a n d numerous ! class known as Cepheids . It varies from the third magnitude t o the fourth in 5 days 8 40 7 . hours minutes seconds Mu Cephei , Of A the fourth magnitude , lies between lpha and

Zeta , below an imaginary line j oining them . It is pr obably the reddest star visible t o the unaided eye in the northern hemisphere , and wa s named by Sir William Herschel the THE 3 NORTHERN STARS . 5

c garnet star . Seen in the bino ular , Mu f Cephei is a very striking and beauti ul object . D r a co is o n e o f the most difficult constella n C n tions to follow . It adj oi s epheus and wi ds alon g the barren reaches o f the sk y near Ursa n o f Minor , and e ds in a line stars parallel to th e —A o f Plough lpha , the third magnitude ,

is on a line with Zeta Ursae Maj oris (Mizar) , Lambda is o n line with Alpha Ursae Maj oris while Kappa is the star between Alpha and n Lambda . The co stellation coils round the sk y until it j oins Cepheus ; then it curves round again and term i nates in three bright

stars Xi , Beta and Gamma near the bound f aries o the constellation H ercules . These three stars with Iota H erculis form a di amond

shaped figure . There are other constellations partly cir cum o la r - a n d A p Cygnus , Perseus ndromeda , but these are practically inv i sible at certain periods and will be di scussed among the stars

o f the respective seasons . We have now completed a survey o f the northern stars whi ch are visible all the ni ght d ni n w a n all the year round . Begin g ith the ll n Plough , the observer wi recog ise the Pole a C a n d o f St r and assiopeia , by means these C he will identify apella and Vega , the two o f watchers the northern heavens . There is som ething awe-inspiring in contemplating the 36 L PRACTICA ASTRONOMY .

o f i s ceaseless revolution these stars , and th feeling is not di minished by the recollection that the motion we are watchi ng is that o f o ur o wn A world projected on the sphere . s : TO an able writer has expressed it ! watch these northern constellations as they follow each other in regular ceaseless procession round the Pole is o n e o f the most impressive spectacles to a m i nd capable o f realising the f actual significance o what is seen . We a re spectators of the movement of one of Nature’ s o f hi machines , the vastness of the scale w ch and the absolutely perfect smoothness and regularity Of whose working so utterly dwarf ! the mightiest work accomplished by man .

CHAPTER III .

TH E STA RS OF W I NTER .

I N the previous chapter a description wa s given of what are known as the circumpolar stars— those stars in the northern heavens which are Situated so close to the Pole that do n o t se t they rise nor , but circle ceaselessly round . They are to be seen every clear night , in position s varyin g with the changing seasons . o f n o t The maj ority the stars , however , are e o f thus situated . They have th ir seasons THE STARS OF WINTER . 37

l a n d o f visibi i ty invisibility , favourable and f n di n o n un avourable positio s , depen g two — factors their apparent di stance from the Pole and their position wi th respect t o the A S un . S mentioned in the previous chapter , di a i n as , the stance of a st r from the Pole hi it creases , the circle w ch describes grows wider and wider . Some constellations , such A A as Perseus , ndromeda and uriga , are partly circumpolar partly seasonal . The circles which they descri be on ly pass very slightly n below the northern horizon . O ther co stella n a s e i tio s , such G min and Bootes , pass below the horizon for a Slightly longer period ; but such groups always rise in the north- east and set - O in the north west . ther groups farther n from the Pole , such as Orio , rise almost due east and se t almost due west ; whi le others again merely ascend a little distance above n in - the southern horizo , rising the south east

- and setting in the south west . O wing to the apparent motion of the Sun o r rs among the stars , , as it appea to us , the apparent dr iftin g o f the stars into the sunse t i a n d tw light , these stars which rise set have f Th their particular seasons o visibility . e nearer the con stellation is t o the Pole the n longer its period of visibility . For i stance , Auriga on ly disappears from view for a Short time . The farther a constellation is from the

T 3 HE STARS OF WINTER . 9

l o f a ll conste lations , is the most brilliant the a - a st r groups , and is lways visible at a con n f r a l v e n i e t altitude o observation . It rises

most due east , culminates midway between

the horizon and the zenith , and sets almost

. O n due west nce see , Orion can never be a n n forgotten . In the e rly eve i g in November c ri and De ember , it is visible sing in the south east ; later in the season it reaches the me

r idi a n o r . , point due south In February and March it is de

- scendi ng in the south west . A o f large proportion people , who have no particular interest in astronomy , are familiar with ri r e O on . The figure is easily An membered . irregular quad rila t e r a l i s formed by the four Q o s Al bright stars , pha , Gamma ,

FI G’ Beta and Kappa . In the centre o f thi s quadrilate ral are three stars almost In equally bright , nearly a straight line slant in g downwards . These are Delta , Epsilon

and Zeta . A Of these seven stars two , lpha and Beta , s are Of the fir t magnitude , and five , Gamma ,

Kappa , Delta , Epsilon and Zeta , of the second . Al - - pha , at the north east or top left hand corner mi Of the quadrilateral , is more fa liarly known ts A by i rabic name Betelgeux . It is a very 40 L PRACTICA ASTRONOMY .

conspicuous Obj ect , shining with a red light which contrasts with the bluish- white radiance f O . Rigel Generally , Betelgeux is inferior in to nl brilliance Beta Orionis , more commo y

- known as Rigel , the star in the south west , o r - the bottom right hand , corner Of the quad rila te r a l ; but at times it in crea ses in bright u hi n ness and o ts nes Rigel . Its variatio s are ll l irregular , but easily fo owed . It is general y believed to have bee n brighter than Rigel in 1 6 03 n , when the Greek letters were assig ed to At the individual stars . that date it was A di n designated lpha , in cati g that it was hi f l then the c ef star o the conste lation . a n d These two stars , Betelgeux Rigel , have been much studied by astronomers . Both are so far di stan t from the Ea rth that it can not be said that the atte mpts to mea sure their A distance have met with success . pproximate measurements , however , have been made . Betelgeux is at least over times more massive than the Sun . It is , as already men ti o n e d a , a red st r , as its atmosphere is much r As hea vier than that o f o ur o b of day . the subject o f spectroscopic astronomy is dealt n with in a other volume of this series , it is unnecessary to mention the methods by which astronomers have reached their conclusion s l ni a . a s a concer ng these st rs Betelgeux is , a ready mentioned , variable star ; and vari 4 THE STARS OF WINTER . 1 able sta rs o f this particular type are generally red in colour . o n i s - i n Rigel , the other hand , bluish white l c wi . n olour , Shining th a clear light Its o y points o f resemblance to Betelgeux are its n imme se distance and enormous size . Its t dis ance cannot be measured , but astronomers have calculate d the m i ni mum di stance at hi . o n w ch it can be placed It is placed , even di the minimum estimate , at a stance so vast i 8 that light , wh ch travels from the Sun in minutes and from the boundaries of the Solar 4 307 System in hours , requires no less than years to cross the mighty void . It must be a sun o f o n e o f enormous size , probably the greatest bodi es in the entire Universe ; it s mass is at least Of times that the Sun , and , as we know , the Sun is inconceivably larger than the Earth . ni - o r t o Gamma Orio s , in the north west p - n i r e right ha d corner of the quadrilateral , is A a quently known by its rabic n me Bellatrix .

At - the south east corner of the figure is Kappa , o f n also the seco d magnitude . The most famous Object in the constellation

O . is , however , the Great Nebula in rion It n d T surrou s heta Orionis , the middle star of ! w o f hi n the S ord Orion , w ch co sists of three n faint stars in a straight li e with Epsilon , the mi ddl o f e star the belt . On a clear night a keen eye ca n dete ct a haziness about Theta 42 L PRACTICA ASTRONOMY . which a binocular shows to be a cloud o f misty light . Even in a small telescope it is a striking spectacle . The haziness expands i - its into a magn ficent cloud like obj ect , and apparent size increases as the telescope em ployed becomes larger . The nebula is a n o f gigantic mass Of glowing gas , thousa ds times larger than the Solar System . Photog r a ph y has shown the nebula to be vastly more, extended than it appears to be when studied with the telescope indeed the whole constellation has been ascertained to be wrapped in nebulous haze . r o f co n O ion , as the most conspicuous the st ella ti o n s , has been known from the earliest s age and is referred to by the early writers . H omer refers to Orion , while we are all familiar with the well - kn own passage in the Book o f C n Job , anst thou loose the ba ds Of Orion Ca n i s Maj o r a n d Ca n i s Min o r Orion i s the index- conste llation o f the winter star groups in the southern aspect o f the heavens . Betelgeux forms a very conspicuous equilateral triangle with two other bright stars , Sirius in n i n n r Ca s M a j o r and Procyon in Ca i s M i o . As the Old rhyme has it

Le t P r o o e x a n d a ss a n e a a r cy n j o in t o Be te lg u p li f , To r ea t e o n e r e S r o w th e o t o n o s ch h p i t wh i ius g l s , m s c spicu u

st a r , T en e e e te v e a fi re fin e a n d v a t h will th e d ligh d i w gu s , '

I ts s a n i s e u a r l la r i ts a st . p q te a , t ria n gu c 43 THE STARS OF WINTER .

The great triangle is one o f the most notice able con figurations in the entire heavens its strikin g appearance bein g due to the bril li a n ce o f the three stars co mposing it and to f d o . the earth stars within Procyon , a star o f fir ni t d —A the st mag u e , is the chief star lpha

' —f i D o o Can s Minor or the Little g . It is the only conspicuous star in an inconspicuous n co stellation . More striking in its appearance o r D o i is Canis Major the Great g . Th s group is famous as containing Sirius—Alpha Cani s — sk S Majoris the brightest star in the y . irius is never t o be seen very hi gh in the heavens

- in these latitudes , rising in the south east and

- setting in the south west . The Dog Star o f has been termed the monarch the skies , a n d so far as mere brilliance is con cerned fully l merits the title . Much Of its bril iance , how due ever , is to the fact that it is comparatively r i n s o n e o f o u nearer neighbours pa ce . Light requires eight years to reach us from the Dog S d tar , as compared with hun reds of years from

Betelgeux and Rigel . Therefore , although Sirius i s probably considerably larger than our Sun i n , it is relatively a small star comparison with other Orbs which appear its inferiors on f n S account o their greater dista ce . irius is a

- well known double star , but the satellite can i n only be seen powerful telescopes . — Ta urus Higher in the sky than Orion are 44 L PRACTICA ASTRONOMY .

ll Ge i two bri iant constellations , Taurus and m ni . m It is impossible to istake the two groups . Ta ur us - o f i i t is north west Orion , Gem n nor h o f east . Taurus is the second the twelve con st ella ti o n s o f di i the Zo ac , through wh ch the Sun moves o n its apparent path round the Ge i i Earth , while m ni is the th rd . Of the two Taurus is the more famous , as it contains - - H the two well known star clusters , the yades

5

4 — s FI G . Ta ur u .

a n d o f the Pleiades . The former is a group

five stars arr anged like the letter V . The o f H d o f brightest star the yades , and indee s Al o r Al the con tellation , is debaran pha

Tauri , which marks the upper left hand Of o f the figure . Epsilon , the fourth magnitude , n s marks the upper right ha d , and Gamma , al o f A d o i . the fourth magn tude , the angle l ebaran is by far the most conspicuous star it is Of a bright red colour and indeed closely resembles 4 THE STARS OF WINTER . 5

n Betelgeux in the neighbouri g constellation . The di stance of Aldebaran has been measured with some approach to certainty , and its mass is believed to be about two hundr ed times o f that the Sun . — Th e Plei a des H igher in the sk y than Alde a H o n b ran and the yades , and the right n o f ha d Side these stars , is the most famous

- — star cluster in the entire heavens the Pleiades . a n d Like the Plough Orion , this cluster has attracted the attention o f man from prehistoric n times . Canst thou bi d the cluster of the Pleiades 7 asks the Creator Of J o b in that Book of the Bible H esiod too says o f the Pleiades

There i s a time when fo r t y da ys the y li e An d o rt n t o n e a e d r o a n e e f y ig h s , c c l f m hum y , referring to their invisibility when the Sun is n passi g through Taurus . Th e Pleiades begin to appear in the late n eveni gs of autumn , above the eastern horizon . ’ At T o f this season we , like ennyson s hero Lo cksle H a ll y , behold

th e Ple ia de s r isin g thr o ug h th e me llo w sha de - Glitte r in g like a swa r m o f fir e fli e s ta n g le d in a silv e r b ra id .

The n ame Pleiades is probably derived ll ma n u . from the Greek Pleiones , y or f Th e Six stars are closely packed together .

Re v ise d V ersio n .

THE STARS OF WINTER . 47

Castor is a double star , but is not within the n - reach of the bi ocular . On the right hand Side of the constellation is a square formed by n G four stars Epsilo , Mu , amma and Zeta . Epsilon and Mu are of the thi rd magnitude and Gamma Of the second ; while Zeta is a

- well known variable , fluctuating from the third to the fourth magnitude in 1 0 days 3 i hours . It can be easily followed w th the un r aided eye o binocular . Zeta forms an equi e o f lat ral triangle with other two stars , Delta o f the third magnitude and Lambda the fourth . o f Finally , close to Mu is a noticeable star Eta , the third magnitude alt—hough slightly variable . e us a n d E i da n us . e L p r R turning to Orion , it is well to note the in conspicuous constella

Le us a n d . tions close to it , p Eridanus Lepus — — the H are i s exactly underneath the m a g n ifi cent star group . There is nothing remarkable

about this constellation ; its four . chief stars , Alpha and Beta o f the third magnitude and G amma and Delta Of the fourth , form the o f l Er i da n us corners an irregular quadri ateral .

is a much less compact constellation . It straggles from close to Orion to the boundaries o f C d etus , and then curves downwar s into the

southern hemisphere . Beta Eridani , of the

third magnitude , can be easily identified from

its proximity to Rigel . — A uri g a A survey of the winter constella 48 L PRACTICA ASTRONOMY. tions is incomplete without reference to one o f A r i u a . the most remarkable of all , namely g ri Starting from O on , the guiding constellation i s n A A . e of winter , it easy to recog ise uriga bov ni Orion , as we have seen , are Taurus and Gemi , the bright stars o f which are o n either side Of di A the space imme ately above Orion . bove di these two , and therefore rectly above Orion A hi and almost in the zenith , is uriga . T s di group , which , as mentioned in the prece ng chapter , is almost a circumpolar constellation , o f o f n is the shape an irregular pe tagon , with n o e Of its sides much shorter than the rest . The stars forming the corners of the figure are A E lpha or Capella , Beta , Theta , Iota and p l silon . Capel a is of the first magnitude and o n e f li o f o the most bril ant all the stars . It o ur is a star Of the same type as Sun , only very much larger and more massive ; in n recent years , it has been found by mea s of the spectroscope to be an exceedingly close o f double star . Beta , the second magnitude , has also been found t o be double by the same method . Theta , Iota and Epsilon are n o t l fo r of the third magnitude , but do cal special mention . Epsilon forms an isosceles a triangle with Eta and Zet , two stars of the fourth magnitude very close together . In Auriga appeared the famous new star Of 1 89 1 . 49 THE STARS OF WINTER . — Perseus TO the right o f Auriga and further o f a along the stream the Gal xy , which here ll - becomes more bri iant , is the well known P erseus o n e o f th e constellation . This group , . most fascinatin g in the entire heavens to the

i s . t beginner, very easily identified Its mos t u no able feature is a triangle , almost eq ilateral , c n n o f Al o f o sisti g three stars , pha and Beta s ni the econd mag tude ,

and Epsilon o f the third . Almost in the cen tre of thi s trian gle but nea rer to Epsilon is a fainter o f star Nu , the fourth n m a g i t u d e . B e t w e e n Alpha and Beta and slightly above the line n n joi i g them is Kappa , also o f the fourth mag tud ni e . g Al P er sei pha is the - r FIG . 5 . P e se us . brightest o r b in a stream o f a hi n n st rs , w ch forms the seco d distinguishi g o f l n a n d feature the conste latio . In order , b n ni n egi g from the highest point Of the stream ,

the stars are Eta , Of the fourth magnitude , o f Al Gamma , the third , pha Of the second , o f H th e o f . Psi the fifth , Delta the third ere

stream curves Sharply round , the stars in the 4 8 P e r sei o f th e curve being , Mu and Lambda 4 5 0 L PRACTICA ASTRONOMY. f 4 3 P e r se i ourth magnitude , and of the fifth . ‘ The only other notable star in the constellation hi ni is Zeta , Of the t rd mag tude , a somewhat

!

i . isolated star , considerably below Eps lon There are three chi ef Objects o f interest in the constellation Perseus to the ordi nary

! r observer with the unaided eye o binocular . T a r e P er sei o r A hese Beta lgol , the famous ! di A P er se i variable the region surroun ng lpha , o r Mirfak and the double cluster near to the P e r s i star Chi e . The name Algol i s Ar abic fo r th e demon and from thi s some astronomers have assumed that the o ld Ar ab astronomers were acquainted wi th the variations in its l ight . Be this as it may , the fact that the star is variable wa s not discovered until com a r a ti v e l p y modern times , although the varia t ions are quite easy to follow with the unaided e e o f y . Probably the reason this is that the normal appearance o f Algol is that o f an ordi

f As . nary star O the second magnitude . Mr

J . E . Gore remarks Shining with a steady light for about 59 hours its lustre suddenly di m i 4 begins to nish , and in about % hours its brilliancy is reduced to about one -thir d o f i ts e normal brightness . It remains at its faint st f o r 1 5 i about m nutes , and then in about 5 lu tr e Th e % hour s recovers its former s . ! variability o f the star wa s di scovered in 1 6 6 9 THE STARS OF WINTER . 51 1 82 by Montanari , an Italian , and again in 7 dri n by Goo cke , a you g English astronomer , wh o i accurately determined the period , wh ch 2 20 45 5 5 is days , hours , minutes , seconds . Goodricke was the first to suggest that the loss o f light was due to partial eclipse Of Algol

' b l o r d . y a large satel ite , dark , almost ark This theory was confirmed twenty years ago o f by the late Professor Vogel Potsdam , by ’ means Of what i s known as Doppler s principle in spectroscopic observations . Vogel applied t o th e n Al the principle Observatio of gol , and he found that before each eclipse Algol was retreating from the Solar System , while after hi each eclipse it showed sign s Of appr oach . T s proved conclusively that both Algol and its invisible companion - star were in revolution o f round their common centre gravity , and Al that gol was not inherently a variable , but merely a double star . Vogel also ascertained that in all probability Algol is a star about o n e ll m i di mi ion les in ameter , and the satellite star about eight hundred thousan d miles — about equal in size to o ur sun the di stance be tween the centres o f the two stars being

about three m i llions o f miles . The presence Of a third member o f this remarkable system

has often been suspected , although not yet

confirmed . To the unaided eye Algol appears nl di n o y a very or nary star , with no outstandi g 52 AL PRACTIC ASTRONOMY . features and it is remarkable that it wa s an ur di it s amate who scovered variations , deter m i r ned its peri od , and put forward the t ue f theory o its variations . Alpha P er se i o r Mirfak i s the centre o f a b o f remarka le region the heavens . When we

Observe this region with the binocular, we cannot but be impressed with its magnificence . o f i There is a festoon stars round M rfak , arranged so symmetrically as t o preclude the idea of a chance scattering . Above Eta and near to the borders o f hi P r ei t o Cassiopeia is the star C e s . Near this star is the magnificent double cluster in Perseus . It is visible to the unaided eye A field as a hazy spot o f misty light . glass shows it much more plainly ; and even in a small telescope it is a striking spec l i s tacle , whi e in a large instrument it awe inspiri ng . Perseus is notable i n astronomi cal hi story as the constellation in whi ch the famous tem po r a r y star o f 1 901 the new star o f the — d h di s new century appeare . T is star was An o f di . r covered by the Rev Dr . derson E nbu gh 1 901 At i ts sur in February . maximum it C i n lli passed apella bri ance , and indeed it was o n e of the most brilli ant temporary star s ever recorded . We have briefly surveyed the chief co n THE O 3 STARS F WINTER . 5

ste lla ti o n s visible in the winter skies and have noted their chief stars and the most interestin g binocular fields . Taking Orion as a starting n i point , the begin er is enabled to ident fy the A other groups . fter all the others have been n l ide tified , Orion sti l remains the chief attrae tion . As a recent American writer has r e marked I have never beheld the first indi cations o f the rising o f Orion without a peculia r feeling of awakened expectation like that Of o n e who sees the curtain rise upon a f An d dr ama o absorbing interest . certainly the magni ficent company o f the winter co n st ella ti o n s o f which Orion is the chief make their entrance upon the scene in a manner ! that may be described as almost dramatic .

It must not be forgotten that , although the winter stars may be see n and identified in and near to cities , they are seen under their most favourable condi tions in the country districts As where the air is clear and pure . the same writer has expressed it In the pure frosty air the star s seem splintered and multiplied n indefinitely , and the brighter ones shi e with a splendour o f light and colour unk nown to the deni zen o f the smoky city whose eyes are dulled and blinded by the blaze of street lights . There o n e may detect the delicate shade of r e li u g e n that nks in the imperial blaze Of Siri s , - Al the beautiful rose red light Of debaran , the

55 THE STARS OF SPRING.

hi Leo — easily kept in mind . T s is the — Lion the fifth o f the constellation s o f the

Zodiac . Leo may be easily found by means Of the A stars Of the Plough—. line drawn from Alpha Ursae Majori s o n e o f the pointers —t hrough Lambda and Mu Ursae Maj oris , di rects the Observer to the stars o f Leo . Per t l n r ec haps , however , the cons el atio may be o g n i se d without thi s aid . Even the most

- o n casual star gazer , casting a glance upward a dl t o any evening of spring , can h r y fail n th e notice a striki g group Of stars , east Of di o r o n th e meridian , west Of the meri an , i s o f merid an it elf , according to the hour the night o r the earlin ess o r lateness o f the se a s n o . The constellation consists Of two parts On the right- hand side a curve o f stars known as the sickle from it s resemblance to the o n - implement Of that name , and the left hand o f f side a group stars in the form o a triangle . 56 L PRACTICA ASTRONOMY . Between the two parts of the constellation t r s . here is a gap , filled by faint sta There are six principal stars in the sickle a n d the star at the bottom at once attracts l r a . u o A ttention It is Reg us lpha Leonis , o n e o f o f fir the fainter stars the st magnitude . The position o f the Sun at the summer solstice was in thi s group when the zodiacal constella t n a n d io s were first arranged , this gave to Leo and its chi ef star a primacy not warranted by the actual importance of constellation or s d tar . Mr . Maun er has Shown this very clearly in his discussion of Leo in A str o n o m y wi th o ut a Telesco pe Our present name for ! the star , he says , is the variant proposed by Copernicus , for the older Latin Rex . ’ t B a silik us A P olemy calls it , the rabs give ’ M a lik i i it yy , the k ngly star , and the cuneiform inscriptions of the Euphrate an ’ o f valley refer to it as the star the king , whilst i n ancient Persia it wa s the chief of the four royal stars . It is its place , however , and not its brilli ance whi ch h a s gained for Regulus i a ll ni th s distinction , for almost the first mag li ! tude stars are its superiors in bril ance . o f o f The next star the curve is Eta Leonis , A the third magnitude . bove Eta , next in f t e o . h curve , is Gamma , the second magnitude

It is a double star visible in the telescope , and

- a favourite object for double star observers . 5 THE STARS OF SPRING. 7

t o f The nex star in the line is Zeta , the third At th e m i o f magnitude . sum t the curve o f — o f the handle the sickle is Mu , the fourth ni d mag tu e ; while below Mu is Epsilon , of the third . In a line with Epsilon to the - fif right hand side is a th magnitude star ,

Lambda Leonis . A little south-west o f Zeta is a point in the h i heavens , unmarked by any bright star , w ch h a s attracte d the atte ntion o f astronomers fo r n ma y years . There is a famous shower of meteors o r fallin g stars known as the November di d meteors . It was scovere early in the last hi century that t s shower was an annual one , generally unnoticed by the casual observer ,

- — but that every thirty thr ee or thi rty four n Th e years it became a mag ificent spectacle . paths of the meteors , traced backwards in the sky , were found to converge at the point H near Zeta Leonis mentioned above . ence e n the met ors were named the Leo ids . The shower is much less notable now than in former years , but November never passes without the appearance o f a few meteors radiating from

Leo . It is unn ecessary t o point o ut that the shower is caused by the Earth ploughing its way th r ough the shoal o f m i n ute bodi es kn own a s e a met ors , and that the meteors merely p pear to come from a poin t whi ch lies in the o f a s Leo same line sight the conste llation . 58 L PRACTICA ASTRONOMY .

Between the Sickle o n the right - hand side Of the constellation and the triangle on the

- left hand Side there is a dearth of bright stars . On the left hand o f the figure we notice the h r h t ee stars , Delta , T eta and Beta , which form - d hi a right angle triangle , of w ch Theta marks ni the right angle . Beta is Of the second mag tude and is oft en spoken Of by its Ar abic ! o f hi name Denebola . Theta is the t rd o f m agnitude and Delta the second . Beta is a n fie ld- interesting object in a glass , as there r e di a e several faint r stars surroun ng it . V i o — Le o i r a — i rg Next to , V g the Virg n is the most prom i n ent conste llation visible

- - in Spring time . Virgo is the large star group to the left - hand side o f Leo and lower in the sk its fi y . It is easily identified , g ure resem Y o n i ts Th e bling a large capital lying side .

o f Y . Al stem the is marked by two stars , pha — —a n d Virginis (Spica) Gamma . The latter star with Eta and Beta forms the right arm o f r m the figu e , and with Delta and Epsilon for s s the left arm . The comparative brightne s Of the stars in Virgo and the dearth Of other bright stars near renders the constellation very conspicuous . o f Y o r Beginning at the foot the , Spica Alpha Virgini s is the brightest star o f the l o f e constel ation . It is the first magnitud f s - hi T hi n and o a blui h w te colour . here is not g THE STARS OF SPRING. 59 particularly remarkable about the appearance o f S d pica to the unaide eye , except its bright ness . The remarkable fact concerning it is e that it is a very close double star , so clos as t o be invisible in the telescope . By means Of the spectroscope , however , we know that the bright star has a dark o r ne arly dark sate llite Th e s hi star . two star , w ch are separated by nl si x l o f l o y and a half mil ions mi es , revolve

0 :

—V FIG . 7 . ir g o . round their common centre o f gravity in about d c o f fift - four ays , with a velo ity y seven miles a secon d and the joint mass Of the two stars a n d sun i is two a half times that of the . It s Obvious that in thi s system we have an arrange ment quite di fferent from that in the Solar S o f t o ystem . The equality in size the w stars makes it impossible fo r the o n e t o revolve d round the other . Both revolve roun their o f common centre gravity . 0 T L 6 PRAC ICA ASTRONOMY .

Proceeding up the stem o f the Y we reach m o f hi Ga ma Virginis , the t rd magnitude . It is a famous double star , but Of course far o f n ul beyond the reach the bi oc ar . It may be seen with telescopes Of 3 and 4 inches i n e r i 1 85 ap ture . The fainter star requ res years

, H to complete its revolution . ere then we have a double star o f exactly Opposite type from Spica . n The four stars which , alo g with Gamma , Y o f form the two arms of the , are all the thi rd magnitude and do not call for particular t is s i n at ention . It intere t g to note that in the region Of the sk y betwee n the arms o f the Y e ni s n a s and B ta Leo , is the point k own the a sa s pole Of the Gal xy . That is to y , thi region o f the heavens is farthest from the l r to Milky Way . If we iken the star y sphere an immense globe and the Galaxy to the o f i ul equator that globe , th s partic ar region t hi Of contains its nor hern pole . In t s region e the sky the stars are most sparsely scatt red . o us a n d r a e — C rv C t r . The sky below Virgo and Leo is divided between two insignificant —Cor vus C Cr a ter constellations , the row , and , u the C p. Corvus may be recognised by the trapezium its hi formed by four c ef stars , Delta at the

- north eastern corner , Gamma at the north a t - s e n western , Epsilon the south we t r , and THE O G STARS F SPRIN . 6 1

e - B ta at the south eastern . Delta , Gamma , Be ta a n d Epsilon are o f about the thi rd mag itu e n d . fif Near to Delta is Eta , of the th Al o f mag nitude ; and below Epsilon is pha , r d the fou th magnitu e . Crater is a less notable nl group . The o y noticeable stars are Delta o f hi o f the t rd magnitude , Gamma the fourth , a n d Al o f t pha the four h . These three stars n form a tria gle . — Hydra a n d (Ja n een On the south and west o f these constellations is the long straggling H dr a group known as y , the longest con in e o n e Of stellation the h avens , and the most n ll di fficult to ide tify . Its most bri iant star A H Ar is lpha ydrae , known by its abic name — o f Al Fard the solitary -the name possibly being suggested by the barren n ess f t o f sk AI F o the adjacent por ions the y . ard is a reddi sh star o f the second magnitude and from its colour was named by the ancient ! r ed Al Chinese astronomers the bird . n H Fard is really the o ly notable star in ydra , whi ch winds from the borders of Libra to the f er borders o Ca n c . This notable though faint constellation may easily be found by means o f H T the most nort hern sta rs of ydra . hese st ars marking the head of the monster are Al d o n - above Far , the right hand Side . Di r e ctly above these stars and between Gemini i s and Leo , the little group Of Cancer , the Crab .

THE O N 63 STARS F SPRI G.

H er hair was stolen from the te mple in whi ch ’ n it had been placed after her husba d s return , whereupon the royal astronomer o f the day declared it h a d been translated to the celestial d regions , and pointe to the shimmering star group as proof o f the truth o f hi s assertion . Th e hi d o f constellation , w le estitute bright a o f st rs , possesses a number faint ones and is an interesting field for the binocular . Above Leo and Virgo and below the Plough l Ca n es is another insignificant constel ation , ! ti ci H Ven a . , the unting Dogs This con stellation , indeed , is almost circumpolar , but is at its best position fo r Observation in nl o n e ri a de si Spring . There is o y b ght st r , g n a t ed A lpha , which is easily found when the Plough is kn own fo r it is the next bright star Eta a o f dl to Urs e Maj oris , the last star the han e of the Plough . It is also known by the some ’ Of C s what ludicrous name Cor Caroli , harles ! H so c eart . It was named be ause it was believ ed by the Royalists to have shone with exceptional brilliance o n the even ing before r fo r Charles II . made his ent y into London the first time after the Restoration . There are no other bright stars in the constellation . To the telescopic astronomer it is chiefly fa n mous o account of the famous spiral nebula . T his magnificent Object , however , is far beyond the reach Of the unaided eye or binocular . 64 T L PRAC ICA ASTRONOMY .

The constellations Bootes and Coron a Bore alis are by some astronomers included among the stars o f spring but it is more correct to include them among the summer stars . They

V - are certainly isible in spring time , but they are most prominent o f a ll i n the short summer wi be nights . Therefore in this work they ll — described among the summer stars i n the next chapter . The average Observer Of the heavens cannot fail to be impressed with the sca rcity o f bright - s stars in Spring time . In the winter skie , s described in the la t chapter , no less than seven stars of the first magnitude are visible o A Sirius , Betelgeux , Rigel , Pr cyon , ldebaran ,

Capella and Pollux , along with a large number o f bright stars o f the second magni tude . On the other hand , Regulus and Spica are the only fir st- magni tude stars amon g the spring r e r constellations p Op . Not only are there d few bright stars in spring , but as compare with other seasons of the year there is a n remarkable dearth Of stars o f all mag itudes . Th e o f hi i s a n d a l reason t s not far to seek , though its consideration leads in to the higher f n problems o astro omy , it may be mentioned here . As was seen in a previous chapter , the Milky Way or Galaxy is the ground- plan of the

Universe . It is itself an agglomeration of E TH STARS OF SPRING. 65 ll di many mi ions of stars , in vidually invisible

to the unaided eye , which are seen collectively f o m . as a belt isty light , Not only is the a n Galaxy agglomeration Of faint stars , but it is a region o f the heaven s in which the bright stars are most thickly scattered . The late M r o n e - . Gore , of the ablest of non professional m i e o f astronomers , exa n d the positions all o n the bright stars the northern hemisphere . H e - found that , of thirty two stars brighter than the second magn i tude twelve lie o n the Milky Way o r on faint nebulous light con n e ct e d with it ; and of those brighter than the thi rd magni tude thirty- three stars o ut o f - T o n . ninety nine lie the Galaxy hus , the number Of brighter stars is considerably more o f than that due to the area the Galaxy . In n se e summer , autum , and winter , we the

Milky Way more favourably than in spring . At thi s season o f the year the part o f the heavens exposed chi efly to o ur view is the region near to and roun d about the pole o f the

Galaxy . The stars increase in density from the pole o f the Galaxy to the Galaxy itself ; therefore the region round about Leo , Virgo , a n d H ydra is naturally the least rich region f o the heavens . Thi s is the explanation o f the relative o f o f paucity stars in the skies spring . In Of summer , although owing to the length day 5 6 6 L S PRACTICA A TRONOMY . light we se e less o f the starry heavens than in S pring , richer and more crowded regions come into view . These will be considered in the n ext chapter .

A T CH P ER V .

TH E ST RS F S M ER A O U M .

I N o f a s the soft air a summer night , s y A fli an merican astronomer , when fire es are n r flashi g their lanterns over the fields , the sta s do not sparkle a n d blaze lik e those that pierce f . O the frosty skies of winter The light Sirius , A m i dvvi n ter ldebaran , Rigel and other bril

- liants , possesses a certain gem like hardness a n d a A cutting qu lity , but ntares and Vega , A the great summer stars , and rcturus , when i n he hangs westering a July night , exhibit a n milder radiance , harmonisi g with the char f ! acter o the season . This description is true to nature : the light o f the summer stars i s ff f di erent from those of winter , but the di fer e nce is chiefly atmospheric there is no peo u liar quality in the light of the various stars

- which are visible in summer time . The chief drawback to the study o f the constellations in summer is the fact that the period o f actual darkness is SO brief . The t n o t so summer stars , in shor , are Obvious as THE STARS OF SUMMER . 67

i do n o t n those Of w nter . They i trude them selves o n the view of the Observer it is n e ce s r T n sary fo him to look for them . hey are no e the less in terestin g o n thi s account there is indeed a certain charm in watchin g the summer sk y darken ing as midnight approaches and t h e o ut o n e Shy stars peeping by one in the heavens . But the student o f the summer Skies must be e n si a sti c H i s i n th u . interest the heavens must be fir st 0 6 stimulated by observation o f the constellations whi ch dom i nate the skies Of win ter and sprin g r e Spe c ti v e l y . — B o o t es Th e chi ef con stellation Of the summer Skies is identified by its ? Ar . principal star , cturus a Th is star is very easily — FI G . 8. Bo o te s . n A recog ised . line drawn from Eta Ursae Majoris , the last star in the n f Ar o . ha dle the Plough , will reach cturus This is o n e method o f findi ng the star ; but Arcturus is so Obvious that it will attract n o f the attentio the most casual Observer . But for the presence o f thi s brilli ant star the constellation B o o tes would be in no way r e At t o markable . the p Of the constellation 68 L M PRACTICA ASTRONO Y. —B t is a triangle formed by three stars e a ,

- Gamma and Delta . Delta , at the left hand o f corner the triangle , is almost in a straight lin e with Epsilon B o o t i s and Arcturus while Arctur us itself forms a triangle with other two r o f fainter stars Eta and Zeta . The figu e e a l Bootes is one not easily rememb red , and though the method o f remembering the stars by means of lines and triangles has , speaking k In o f generally , many drawbac s , the case nl Bootes it is the o y method practicable . Ar o r Al B o o ti s o n e o f cturus , pha , is the most i n m brilliant stars the heavens . The ajority Of astronomers consider Ar cturus to be Slightly more brilli ant than Vega and Capella ; but ni o n i there is not una mity th s point , for the h r o f f r t ee stars are dif erent colou s , Vega being - Ar c bluish white , Capella bright yellow , and t l i d . urus a deeper yel ow , Sha ng into orange It is therefore difficult to determine the m i nute differences in magni tude ; yet the majority Of astronomers believe Arcturus to be the o f h r brightest the t ee . It is therefore the ll o f most bri iant star north the celestial equator , o f and with the exception Sirius , the brightest star visible to observers in the northern hemi sphere . A rcturus , which is situated at an enormous distance from the Solar System , appears to be A a star Of gigantic Size . Dr . Elkin , an merican 6 THE STARS OF SUMMER . 9 a stronomer , made an attempt to measure the o f A H e distance rcturus . found that the ’ di due star s splacement , to the change in the ’ o Observer s position , when he is at exactly p ’ — po site points of the Earth s orbit i n January a n d n — July respectively , for insta ce is about equal to the apparen t distance between the heads Of two pins placed an inch apart and 1 80 viewed from a distance Of about miles . . d d ’ The istance deduce from Dr . Elkin s meas ur e m e n t is Of course by no mean s beyond doubt ; but assum i ng that the estimate is u fairly near the tr th , Mr . Garret P . Serviss , A an merican astronomer , has calculated that if the Eart h were Situated midway between the Sun and Arctur us it would receive over 5000 times as much light from the star as from the Sun and assum i ng that the radiation Of the n star is the same per u it of surface as the Sun , he finds that Ar cturus exceeds the Sun in volume by about times . O l f the other bright stars in the constel ation , o f Epsilon is the second magnitude , Eta , Zeta , a n d o f Gamma Delta the third , and Beta and

Mu of the fourth .

. d Mr Maun er compares Bootes to Orion , A is remarking that when rcturus excluded , the principal remaining stars o f the con n stellation make up a represe tation , pale and d a ll istorted ; it is true , but a representation for

1 THE STARS OF SUMMER . 7

Of the most difficult for the observer t o know As o ur n thoroughly . gla ce travels eastward along the heavens we reach richer regions where the stars are more profusely scattered for we are again approaching the v 101n ity o f th e l o n e o f Of Mi ky Way , the branches which O passes through phiuchus and Serpens . The stars are not grouped in easily remembered n o r figures , are the constellations themselves marked Off one from the other . Serpens and

Ophiuchus , for instance , intersect in a manner which is very puzzling to the beginner in n e constellation study . The key to this i t r section i s found i n the names o f the star-groups v n themsel es . Serpe s is Latin for the Serpent while Ophiuchus i s the Serpent b bearer . On the Old glo es in which the mythical figures are represented , Ophiuchus the serpent- bearer is represented as engaged in a life- and- death struggle with the serpent which i s coiled round him . The natural grouping o f the stars has in this case been ig nored for the purpose o f representing the o ld sk fable in the y , with the result that it is very difficult for the beginner to recogni se which stars belong to Serpen s and which to A Ophiuchus . bove these two groups i s H co n ercules , which , although not a striking n t o . stellatio , —is much easier follow H ercules On the left o f Corona Borealis 72 L PRACTICA ASTRONOMY . and somewhat higher in the sky than that o ur constellation , attention is attracted by four stars which form a quadri lateral which is almost a square . These four stars are Pi Of H er cules o n - o n , the top left hand corner , Eta - o n the top right hand corner , Zeta the bottom - o n right hand , and Epsilon the bottom left All o f hi hand . four are the t rd magnitude . C o f lose to Pi is Rho , the fourth magnitude , o n while a straight line from Eta to Zeta , but th e considerably nearer to the former star , is - H famous star cluster in ercules . This wonder ful celestial spectacle is beyond the reach Of the unaided eye , but it may be noticed if looked for with the binocular and seen fairly well with a small telescope . Larger instruments have shown it to be o n e Of the most wonderf ul — obj ects in th e entire heavens contain in g many f n thousands O stars . For ma y years it was believed that the cluster represented a mere co n local aggregation of stars , but our whole cepti o n o f its place in the Universe has been revolutionised by a remarkable investigation carried through within the last few years by

A . a distinguished merican astronomer , Dr

H arlow Shapley . From an exhaustive study o f the colours and absolute mag n itudes of the d th e stars in the cluster Dr . Shapley reache conclusion that it is situated a t a di stance so great that light requires years to THE T O 3 S ARS F SUMMER . 7

f a n d travel rom the cluster to our system , 1 100 years to cross from o n e side Of the cluster

to the other . In fact the cluster is possibly n d an isla d universe , though consi erably smaller in extent and perhaps not altogether d n n ur n in epe de t Of o Galaxy . That it is a alo gous i n its nature is shown by the recent work Of h f . O Dr S apley , who has detected the presence n n n n a zo e of galactic co ce tratio in the cluster ,

similiar to the Milky Way . Professor Edding t o n has truly remarked that were we tran s planted into the midst of the great H ercules cluster o ur knowledge Of i ts con stitution could so S scarcely be precise as that which Mr . hapley has di sco v ered at a dis tan ce of light years ; a n d the labour would have been i n b ! compara ly greater . Thus when we Observe the cluster it is well to realise that we are lookin g far beyon d the limits o f S n the tellar System into vistas of infi ity . From the quadr ilateral in H ercules the other n Al stars of the co stellation may be found . d e o f most irectly below Zeta is B ta , the n d second mag itu e , the Space between Zeta a n d Beta being a little greater than that n a n d betwee Zeta Eta . Close to Beta , but i n G Slightly lower the Sky , is amma , between a n d d TO the third the fourth magnitu e . the left of the quadrilateral i s a portion o f the heavens in which it seems at first very difficult 74 L M PRACTICA ASTRONO Y.

a n to discern y order in the scattered stars . T r hi here is , however , a cu ve of stars w ch may n be remembered . Beginni g with Beta after o f a considerable space we come to Delta , the As d third magnitude . far from Lamb a as

Lambda is from Delta , we come to Mu , of the T hi . h e ur t rd magnitude curve t ns more sharply ,

a n d - ni and we reach Xi Nu , two fourth mag tude A stars comparatively close together . gain there is a considerable gap and we reach Theta , hi also of the fourth magnitude , w ch is almost — in a straight lin e with three stars so that the T curve becomes practically straight . hese are fifth - n 90H a mag itude star marked erculis , Iota o f d a n d e n o f the third magnitu e , B ta Draco is H equal brightness . In fact Iota erculis is n aturally o n e o f the four stars form i n g the — n otable diamon d- shaped figure in Draco the other three being Xi , Beta and Gamma Dra n co is . — O h i uch us a n d Se en s. A H ul p rp lpha erc is , a bright reddish star , irregularly variable , may — be found almost directly below Delta a con si r l n de a b e stretch Of sky i tervening . Close to Al c i th i s star is pha Ophi u h . So close indeed are the two stars that Alpha H erculis seems to belong more naturally to Oph i uch us than to H B Al hi uch i d . O ercules elow pha p , a secon n e i d d mag itude star , is B ta of the th r magnitu e hi n o t and again below t s star , although in a THE STARS OF SUMMER . 75

i n f straight line but a line slanting to the le t , i G d d . is amma , of the th r magnitu e We may note that in t his constellation appeared the f 1 6 04 o . famous new star In this same g roup , t o o n wi , is situated a fai t star th a very large

proper motion , discovered by Professor Y O 1 9 1 6 Barnard Of the erkes bservatory in . This faint star is Situated at a distan ce whi ch si x light requires a little over years to traverse . It is with the single exception o f Alpha Ce n n tauri our nearest known stellar eighbour . O o f bviously , it must be one the smallest and n f fai test o the stars . n o w o ur S er en s We may direct attention to p , which begins below Corona Borealis in the e H A d space betwe n ercules and Bootes . win i n g stream of stars may be traced from near the boundaries o f H ercules - Kappa Serpen tis t n B o f of the four h mag itude , eta the third , Al o f n Delta Of the third , pha the , seco d (near hi o f t to w ch is Lambda the four h) , Epsilon o f d — the thir , and after a considerable gap f o hi . Delta , Epsilon and Zeta Op uchus It is almost impossible t o remember these stars n from any figure or groupi g . They must be a n d followed star by star , it is fortunate for the observer that they generally r un i n lines

and streams . There are some magnificent n hi l t binocular fields in Serpe s , w ch is wel wor hy o f n careful attentio . 6 L 7 PRACTICA ASTRONOMY .

Lower down i n the heavens are the thr ee least - known constellations visible to north — ern Observers Libra , Scorpio and Sagittarius . hi di n These , w ch are zo acal constellatio s , only rise a short di stance above the horizon a n d Of - as their period visibility is in summer time , when the even in gs are so long clear and the n - period of dark ess is brief , these star groups are among the least known in the heavens . i b a —Li br a o r L r , the Scales , the seventh n constellatio Of the Zodiac , lies east of Virgo A and considerably lower in the heavens . lpha , A Delta and Beta form a triangle . lpha is l o n almost exact y the ecliptic , the line which ’ marks the Sun s apparent path in the heavens . fie l - In the d glass this star is a beautiful double . f e Beta is o a green ish hue . Th is star is b lieved to have decreased in magni tude withi n the Of last two thousand years . It is now the second magnitude whereas Ptolemy cata it f r d logued a s a star o the fi st magnitu e . — Sco i o . t co n s i c rp Nex to Libra , but more p uo us S co r i o although lower in the Sky , is p —the Scorpion—the eighth constellation of the o r o f hi Zodiac , rather the part Scorpio w ch is v i sible to Observers in o ur northern latitudes . In more southern latitudes Scorpio is o n e o f the most m a g ni fici e n t constellations in the heavens it is not only rich in stars but it is immersed in o n e o f the most brilliant portions THE STARS OF SUMMER . 77

Th e S Of the Milky Way . star Xi of corpio , o n S n which is a line with Mu erpe tis , is the first of the curve of stars which distinguish the n - norther portion of the star group . Below Xi a n d Nu n d lies Nu , from the curve i clu es Beta , Al A Delta , Sigma , pha and Tau . lpha , better k it s A nown by Greek name of ntares , is a star

— S o . FIG . 9 . c rpio

o f the first magnitude . It is Of a fiery red o f An t -Ar colour , hence its name es , the rival o f Ar o r o f es Mars . It is a star the same O spectral type as Betelgeux in rion . When Observed with a good telescope it is seen to be d l - a ouble star , the little sate lite orb being of a ni n gree sh colour . For ma y years these colours —red and green—were thought to be the effect

9 THE STARS OF SUMMER . 7

other runn i ng straight thr ough Sagittarius in to

Aquila . r a — - n Ly Thi s star group cannot be mistake . It lies to the left o f H ercules and to the right f o f the stream o the Galaxy . Its most dis t in ui sh i n g g feature is its brightest star , Vega o n o r Alpha Lyrae . In the chapter the n t d or hern stars , reference has been ma e to i Vega , wh ch like Capella is a circumpolar star , and which occupies the position i n summer l i n n n i n which Capel a holds wi ter , bei g high - hi the sky . Vega , whose light is of a bluish w te o n e o f tinge , is the most brilliant stars in the . d n Sky . It appears to be situate at an imme se d n a n d ‘ ista ce from the Solar System , to be a star of about th r ee o r four times the light o f S n o ut giving power irius , which co siderably hi s nes Our Sun . Th e con figur ation o f Lyr a is easily remem o f bered . On the left Vega are three stars o f d lo the fourth magnitu e , Epsi n , Zeta and o f a n d Delta , and two these , Epsilon Zeta , B e form with Vega an equilateral triangle . a n d r low Vega are Beta Gamma Ly ae , both o f d n d the thir mag itu e , which form a quadri lateral with Delta and Zeta . These are the hi c ef stars Of the constellation . Of these stars Beta is notable as a famous Of variable star , the variations which are easily f o . within reach the unaided eye . It varies 80 L PRACTICA ASTRONOMY . from the third to the fourth magni tude i n 1 2 2 1 4 days hours 7 minutes . The variations Of this star are believed to be due to the r e v o lu o f two ll tion stars , one less bri iant than the n n other rou d their common ce tre of gravity . d n The stars , accor i g to Newcomb , are of n u equal size and almost in contact , and the smaller body is much brighter than the larger .

' The system thus revealed is certainly o n e Of the most remarkable in the heavens . This variable star is a very suitable Object for t h e observer who is commen cing the study o f variables , as its changes can all be followed by the unaided eye . i s Epsilon Lyrae a double star , visible as such to keen eyesight . The binocular easily reveals the star as double , and a small tele scope Shows each Of the two t o be itself double so in Epsilon , Lyrae we have a quadruple star . i n Perhaps , however , the most interesting star i s the constellation Delta Lyrae , not on account o f o n n n i n the star itself , but accou t Of a poi t the Sky near it . The most reliable astronom ical calculations have shown that the Sun , n carryi g with it the Earth and the planets , is travelli ng towards this portion Of the heaven s wi th a velocity of about eleven miles per As Si r second . Robert Ball has remarked The speed with whi ch this motion o f o ur system is urged is such as to bri ng us every THE STARS OF SUMMER . 81 da y about miles n earer t o this part As o f the Sky . you look at Delta Lyrae

- to night , you may reflect that within the last twenty- four hours you have travelled towards it through a di stance of nearly three- quarte rs l f S O l of a mi lion o miles . great are the stel ar distances that a period o f not less than o ur years would be required before system , even S moving at this impetuous peed , could traverse

‘ a di stan ce equal to that by which we are ! o f separated from the nearest the stars . The d a sk n observer may be tempte to , whe then shall we reach Delta Lyrae ? In all proba l b i it . y we Shall never reach it For the star, o wn like our own Sun , probably has its motion , and even when o ur system in the course o f f — if thousands o—thousa nds of years it is then in existence does reach the place now occupied by Delta Lyrae , that star will be far away n AS from its prese t position . we contemplate the region o f the heavens towards which we a r e t moving , surrounding this little star , grea thoughts o f our world and i ts destiny arise in o ur m i nds . d C A Some astronomers regar ygnus and quila ,

- the adjacent star groups , as summer con ste lla ti o n s ; but we shall consider them a s autumn groups , because , although well seen in summer, they are seen in their full glory in e the autumn s ason . 82 L PRACTICA ASTRONOMY .

C A T H P ER VI .

TH E ST RS F T N A O AU U M .

I N the calm clear skies of autumn the most nota ble feature on a moonless night is the majestic sweep Of the Galaxy spanni ng the hea vens like a great arch . In September and October the Milk y Way is seen to its fullest a dvantage ; and in i t s course in thi s part of the heaven s it passes through some of the o f At most wonderful regions the Sky . this season o f the year it is easier to comprehend the true nature o f the Milky Way than at As n others . was mentio ed previously , it is the g round- plan or equator of the entire Universe o f stars ; the stars are there much more nu u s n m e r o than in other portio s of the heavens . A number o f observations with a telescope o r even with a binocular is sufficient to Show that this crowdi ng o f the stars towards the o r Galaxy is a fact . In a telescopic binocular

field , in this very region the observer may count as many as fifty o r sixty stars ; while in an equal field in Virgo or o n any part of the a he vens , near to the galactic poles , he may x count as few as five or si . The Galaxy is the fundamental reference plane of the entire Uni f o . verse , just as the equator is the Earth In T HE STARS OF AUTUMN . thi s chapter we shall di scuss the constellations o f o n autumn , beginning with those the

Galaxy . — Cygn us Looking up to the heavens o n ni an autumn eve ng , and glancing along the

Galaxy , it is impossible to overlook what is , if not the most brilliant , perhaps the most interesting constellation in the entire heavens . C n u s yg , the Swan , is immersed in one Of the f most brilliant parts o the Milky Way . It is so situated to the left Of Lyra , but it is con

’ spi cuo us that n o di rections are required to find it . The constellation is shaped like a cross ; indeed so Obvious is the cruciform shape tha t i t h a s often been termed the Northern ! At o f Cross . the centre the cross is the star o f Gamma . The horizontal arm the cross is n b e marked by Epsilo , Gamma and Delta , ni r n di cu gin ng at the left hand side . The pe pe A lar arm is marked by lpha , Gamma , Eta and a ni n Bet , begin g with the uppermost star , e di almost in a straight lin . In ad tion there n o t is another bright star, Zeta , included in the cruciform figure . Of all constellations Cygnus includes the grea test vari ety o f notable stars from the point o f view Of the Observer with the unaided eye or i r b nocula . Beginning with Gamma , the cen o f n l o f tral star the co stel ation , the second a i s m gnitude , it to be noted that it is the 84 AL M PRACTIC ASTRONO Y .

o f e central star a very wonderful r gion , being itself the last star o f a curve or crown of A ni b . C A stars lpha yg , also known y its rabic n o f o f name of De eb , is one the faintest stars the first ma gnitude and the region surround in g thi s star is even more strik ing than that round Gamma Cygni . The star is thickly im mersed in the Galaxy and well repays o b servation with the binocular . The boundary

- 1 . n . FIG . 0 Cyg us between the ga lactic light and the darkness o f the small rift in the Mi lky Way near the star is marked by a stream or line Of stars whi ch appears di stin ctly connected with the nebulous f light o the Milky Way . With the aid o f the bino cular it i s ea sy 6 1 n to find Cygni , the seco d nearest star in the l northern hemi sphere . In a straight ine from A o f lpha Cygni , parallel to the horizontal arm a a the cross , we re ch Nu , a st r of the fourth THE O STARS F AUTUMN .

n n magnitude . Prolongi g the li e not quite so di s n Al t o far as the ta ce from pha Nu , we i i reach a fa nt star of the fifth magnitude . Th s i s 6 1 o n e o f the famous Cygni , the nearest stars n in the heavens . This star is dista t from the Solar System times the di stance o f the

Earth from the Sun . Light requires about se v e r e a r s k y to reach the Earth from this star , which is thus much nearer to the Solar System than any Of the most brilliant stars in the sk i s northern y . Relatively to the Sun , it a very small sta r . To - the naked eye Observer , the brilliance

Of the Galaxy in Cygnus is very noticeable . A a n d There is a luminous spot north of lpha , between Beta and Gamma the galactic light

i s . very brilliant Perhaps , however , the most remarkable Object in the conste llation i s the A fie l s i . d tar Beta , Of the th rd magnitude o r ll glass , better still a sma telescope , shows the star to be double , the large star , Of the ‘ ni n third mag tude , bei g topaz yellow and the A smaller o n e sapphire blue . view Of this

- —— st ar is a never to b e forgotten spectacle . ' At the risk o f a di gression we may tur n o ur t u a at ention briefly to the colo red st rs , C n such as Beta ygni , and to the conditio s exist in g o n planets revolving round any of these t o n e o f d s ars . Proctor, in his books , discusse the scene visible from any planets situated

87 THE STARS OF AUTUMN .

- with Theta , pointing north west , are other At a n d a . two stars , Eta Delt the extreme north- wes tern corner Of the conste llation are two stars Zeta and Epsilon and at the south western extremity is Lambda . Of A l Al t the stars in qui a , pha is Of the firs ni a o f mag tude , Gamma , Thet , Delta and Zeta the third ; Beta betwee n the third a n d the

rt a n d l n Of . fou h , Epsi o and Lambda the fourth t i h i Eta is a variable s ar , vary ng from the t rd magnitude to the fourth in 7 days 4 hours . Al A n A pha quilae , better k own by its rabic n o f A s m i ame ltair , stand dway between Beta and Gamma . It is a bright star Of the first - h e i o f e . a s magn tude , a bluish whit tint It b en calculated that light requires about seventeen Al a a n d years to travel from t ir , whether this n calculatio be correct or not , it is certainly nearer than many other stars Of the first magni A tude . The Galaxy is very bright in quila , n although scarcely so striki g as in Cygnus . Lambda stan ds on a bri ght spot o f mi lky S S o bi eskii light , which is known as cutum ’ ! S o bi e sk i s Shi eld . un 8 1 9 1 8 r On J e , , a brilliant temporary sta A c t o n blazed out in quila , lose the bou dary o f At Serpens . maximum it surpassed Nova P e r se i wa s , and the most brilliant Nova 1 6 04 i t s i since . By September l ght had de As creased to the fifth magni tude . in the case 88 L PRACTICA ASTRONOMY .

P e r se i A Of Nova , Nova quilae was observed f independently by a number o Ob se rvers . Between Aqui la and Cygnus are thr ee in signi ficant little groups which scarcely deserve n s n l n A to be desig ated a co ste latio s . bove the Al a n d S a i tta three stars , Gamma , pha Beta is g , A a the rrow , which cont ins no very remarkable Obj ects and might well be included in Cygnus o r A qui la . To the left and slightly lower in a D el h i n us the he vens is p , the Dolphin , the f most conspicuous o the three groups . It li es to the left o f the Galaxy and is easily noted on ni e a s a clear ght . Ther are four st r arranged o f Al in the form a trapezium , pha and Beta

o n o n . the right , Gamma and Delta the left Beta is o f the thi rd magnitude and the other A i Vul three Of the fourth . bove Delph nus is ecula n o p , the Fox . It contains notable stars , and is generally di sregarded by astronomers . — Capri corn us Below Aquila and to the left o f Ca r i co r n us Sagittarius is p , the Goat , the tenth Of the zodiacal constellations . The chief o f ri A stars Cap cornus , lpha and Beta , may A be easily found exactly below ltair , much sk lower down in the heavens . The y is much n A i more barren here tha in qu la , for the Galaxy

Slopes away in to Sagittarius a n d Scorpio . A C two lpha apricorni , the uppermost Of the stars , is a double star , visible to the unaided Th e eye , and well seen in a binocular . two 8 THE STARS OF AUTUMN . 9

n a n d e stars have no con ection , merely app ar close together because they are in the sa me o f t d a s line vision . Be a is also a ouble star , a A a seen in the binocul r . Both lpha and Bet Al are stars o f the third magni tude . most in a line with Beta are the stars Theta , Iota and o f a e Gamma the fourth m gnitude , and D lta i n a n i . Of the th rd They are not , however . y C n i s way notable . On the whole apricor us not a particularly interesting constellation to the Observer either with the unaided eye o r the binocular . — A quari us a n d Pi sces A similar remark a p A ua r i us a n d P i sces plies to q , the eleventh and twelfth constellation s o f th e Zodi ac A o f respectively . quarius fills a large part n i n f d ri the heave s , stretch g rom the boun a es Of A n quila above Capricornus dow to the horizon . Alpha Capricorn i i s almost in a straight line l A with Epsilon , Mu , Beta and Apha quarii . n ur d Of Epsilo is of the fo th mag nitu e , Mu the a n d A f O . C fifth , Beta and lpha the third lose A Of to lpha is a compact group four stars , the most notable feature i n the con stellation a n d n o t Gamma , Zeta , Eta almost , but quite , li in a straight ne , and Pi above Zeta . Gamma o f n Of and Zeta are the third mag itude , Eta t i the four h and Pi of the fifth . Below th s dr n a group is a qua ilateral , consisti g of Lambd , a Theta , Iota , and Delt . On a clear autumn 90 L PRACTICA ASTRONOMY . evening a bright star i s sometimes to be seen n A hi Fo a l glimmeri g below quarius . T s is m o f m i haut , the first magnitude , the chief lu nary o f n P i sces Austr a lis the southern constellatio , h i n the Southern Fish . T s star is only see n o ni eve ngs when the horizon is specially clear . — — Pisces the Fishes the twelfth conste lla o f d A a n tion the Zo iac , is , like quarius , unin t e r e sti n ll g conste ation with no bright stars , but it is easy to follow , owing to the symmetrical n hi b e arrangeme t of its stars . The c ef stars n i A e gin ng at the borders of quarius are B ta , 4 1 P i scium Gamma , Iota , Omega , , Epsilon , ! i Al A Mu , Nu , , and pha . nother stream runs A a n d upwards from lpha , includes Pi , Eta , Chi l a n d Rho , , and Upsi on , Eta , Gamma , the a re o f brightest stars of the constellation , the t ni four h mag tude . — Cetus To the left o f Aquarius and lower down in the heavens than Pisces is the large

Cetus . constellation , the Whale The figure of

Cetus is fairly easy to follow . Mr . Maunder f A O . compares it to that a lounge chair lpha , i Gamma , Delta , and Om cron mark the head

o f . rest the chair Zeta and Tau , Theta , Eta , n and Beta form the lower portio of the figure . A o f n d lpha and Beta are the seco d magnitu e , G o f amma , Zeta , Tau , Theta , and Eta the

d . s r e thir , and Delta Of the fourth The mo t is i markable star in the constellation Om cron , THE STARS OF AUTUMN . 91

generally kn own a s Mira Ceti - the wo n o n e o f r e derful star Of Cetus . It is the most nli Al ma rkable o f variable stars . U ke gol and the other variables whi ch have been noted in i n previous chapters , M ra ru s through its cycle f n o t o . variations in days , but in months The e d is - p rio not regular , like the short period vari

able stars , but varies considerably . On the i s 33 1 h a s average it about days . The star

been under observation for three centuries , and r has been followed th ough many cycles . It varies from the third to the ni nth m agnitude a s ul a r e , but sometimes at maximum it is much more brilliant , and has been known to o f reach the first magnitude . The variations Mira have never received any completely satis factory explanation ; they are certainly not Al a n d r due to eclipse , like g ol Beta Ly ae . Probably they result from great internal n disturba ces . — Eri da n us. a n d Ari es Between Cetus and is Er ida n us d Orion , the River , escribed in the n n l A chapte r o the wi ter constel ations . bove Ce tus and to the left o f Pisces and the right o f i s A r i es Taurus , the Ram , the first Of the di s e l h r zo acal con t l ations . There are only t ee Al e m bright stars , pha , B ta , and Ga ma , arranged i e in a neat l ttle group , Beta and Gamma b ing e Al o f a clos together . pha is the second m g ni t o f a o f th e ude , Beta the third , and Gamm 92 AL M PRACTIC ASTRONO Y .

. a fir fourth Gamm is a double star , the st 1 6 6 i discovered telescopically , in 7 ; but it s beyond the reach of the binocular . — Peg a sus Returning to Aquarius we recog nise above that star- group a very noticeable constellation in a somewhat barren part o f the sk - P e a sus o r W d H Th e y g , the inge orse . most notable feature about Pegasus is the so ! o f called Great Square Pegasus , although strictly speaking the title is incorrect , for the

— 1 . 1 . P a FIG . e g sus star at the top left - hand corner belongs to the s e A is neighbouring con t llation ndromeda . It ni impossible to fail to recog se Pegasus . The great square is o n e o f the most notable con fi ur a ti o n s nl o n g in the heavens , not o y account o f the brightness of the stars forming it , but also because Of the deart h o f bright stars f All o f withi n the figure itsel . four stars the f e square are o the s cond magnitude . Beta - Al Pegasi is at the top right hand corner, pha THE O STARS F AUTUMN . 93

- at the bottom right hand corner, and Gamma - n d at the bottom left ha corner . C a n d o f lose to Beta are Mu , Lambda , the ni An r ul d fourth mag tude . i reg ar qua rilateral A is formed by lpha , Zeta , Theta , and Epsilon , a ll hi of w ch are easily identified . — A n drom eda Although Pega sus is so notice a l n ul able constel ation , it is si g arly barren n r o r ds O in interesti g sta s binocular fiel . f more inte rest is the neighbouring con stella A dr eda As n d Al n om . tion already me tione , pha An dr o m e da e is the star at the top left-hand corner of the great square . Almost but not qui te in a straight line with Alpha are Beta and Gamma An dr o m e da e f n B e all three are O the second mag itude . Al n tween pha and Beta , but below the imagi ary n o f li e joining them , are Delta the third mag

ni tude o f . , and Epsilon the fourth Delta Of the third a n d Epsilon Of the fourth are almost in a straight li ne with Pi ; perpendi cular to n n n A the li e joi i g lpha , Beta , and Gamma , is

hi l n . a line w ch a most j oi s Mu , Nu , and Beta The star Nu is only interesting o n account o f its proximi ty to one of the most famous obj ects — in the heavens the great nebula in An dr o m i l eda . Th s famous nebula is easi y visible to a person Of average eyesight , being faintly visible bin o c to the unaided eye . It is well seen in a ul ar , and even in a small telescope it is a very

THE SOUTHERN STARS . 95

o f di constellations Perseus and Taurus , scussed in the chapter o n the winter constellations . These fine groups come into prominence in n i n t the autum , but it is win er that they reach their most favourable position for Obser vation .

I I CHAPTER V .

TH E S OU TH ERN STARS .

A D I S TI NGU I SH ED writer o n astronomy has remarked that there i s a strange unforget table sen sation i h the first voyage from our high northern latitudes to the southern hemi di n Sphere . Besides the sappeara ce of old frien ds and the comin g into sight o f stranger n stars , the known stars that still remai to us n il adopt most u fam iar attitudes , and these become more a n d more perplexing the further ! south we go . In other words , a considerable number o f the constellation s visible in these b A latitudes are invisi le in ustralia , South A ri A f ca and South merica , while the constella tion s which are visible here are seen inverted . As di was seen in the prece ng chapters , a considerable number o f stars visible i n the s t e northern hemi sphere do n o t e . O n ev ry se e clear night we are able to the Plough , C s as iopeia , the Pole Star and other notable 96 L PRACTICA ASTRONOMY . A f stars and constellations . number o stars are visible to us in their different seasons , such as Orion , Leo , Virgo , and generally e l o f Sp aking , the constel ations the Zodiac while a considerable number o f star- groups are totally invisible to us in the north , because ur T they do not rise above o hori zon . hese e are the southern circumpolar stars . S en from n o t the southern hemisphere , these stars do se t ; they occupy the same position to the in habitants of the southern lands as the nor th ern circumpolar stars do to u s . To the dwellers A Af a n d A in ustralia , South rica South merica , C a n d n the Plough , assiopeia , other norther star- groups are quite invisible ; o n the other ll hand , Orion , Pegasus and the conste ations Of d the Zo iac are v i sible from both hem i spheres . Th e southern sk may be divided into two — y portions a portion rich in stars and a port ion poor in stars . e S co r i o We may conveniently b gin with p , a i a s in constellation wh ch , was noted a previous chapter , is not seen to advantage in northern d its latitu es . In the south Scorpio is seen in full sk magnificence high in the y , almost exactly u s o f overhead . Following the co r e the Galaxy — — here very brillian t we reach the constella l Lu us o r f A r a A . tions p , the Wol , and , the tar t e Of its Lupus is a notable cons llation , three stars be ing brighter than the thi r d magnitude . THE SOUTHERN STARS . 7

Followi ng the course o f the Galaxy we come Cen ta ur us o r th e to the three constellations , , e ur Cr ux o r Ar o Na v is C nta , the Cross and g , r A o the Ship rgo . These are three very famous groups . Centaurus has ten stars brighter than hi d Al . i m the t rd magnitu e pha and Beta , m er se d o f lk o f in the stream the Mi y Way , are fir A d o n e the st magnitude , lpha being in eed sk r Of the most brilliant stars in the y, inferio n o ly to Sirius and Canopus in brilliance .

0 A — 12 . n ta r s r . FIG . Ce u u a n d S o uthern C o ss

Alpha Ce ntaur i is interesting as the nearest f di wa s a t h e o the stars . Its stance me sured in 1 83 1—2 H As years by Thomas enderson , tron - o f d H a n d omer Royal at the Cape Goo ope , afterwards Professor o f Astronomy in the Uni versity o f Edinbur gh a n d Astronomer Royal for Scotland ; a n d in point Of fact it wa s the first star whose di stance was success l It i s d n ful y measured . istant about twe ty

five billions o f miles from the Solar System . is s l a s o r It al o wel known a binary , revolving 7

99 THE SOUTHERN STARS .

o r o r Malus , the mast Vela , the sails Puppis , A o r n o r . the ster , and Carina , the keel rgo contains fifteen stars brighter than the thi rd n o n e o f i - n mag itude , wh ch is the well k own h i o f Canopus . T s orb is , with the exception a n d di s Sirius , the brightest star in the sky , its so nl ta nce is vast that it can o y be estimated . In this constellation t o o is situated Eta ! Ar gus , the famous link between variable i n co n and temporary stars . Originally an s i cuo us Sir n p star , it was Observed by Joh H erschel in 1 838 to blaze up to the first mag n it ude A d , when it equalled l ebaran in bril lia n ce . Five years later it equalled Canopus , a n d was o n e o f the most brilli ant stars in the sk t h e d y . Since then star has stea ily de in e n o w creased magnitud , and it is barely d visible to the unaide eye . A i A fter leav ng rgo , the galactic stream t O passes into Canis Major , which is seen greater advantage in the southern latitude t - than in the nor h ; this star group , however , d was escribed in an earlier chapter . We have described the course o f the Galaxy in the southern hemisphere in other words , n o f the rich region . The remai ing portion the southern circumpolar heavens is very poor in stars . The south celestial pole is situated in — the constellation Octa n s a group very poor o r b a s in stars , containing no as bright the 100 L PRACTICA ASTRONOMY . d fourth magnitu e . The star nearest the south Octa n i s ern pole is Sigma , Of the sixth magni t vi so ude , just sible to the unaided eye there is no south pole star in the true sense o f the word . Round Octans are a number of star — groups equally inconspicuous Pavo , Mensa , H A & c Dorado , ydrus , Toucan , pus , . The paucity o f bright stars is relieved bv the presence Of the two remarkable objects vari ! o usl n y k own as the Magellanic Clouds , o f l Nub e c the Clouds Mage lan , and the ! a r e t o ulae . These two objects peculiar the m i southern he sphere , and have no counterpart k in o ur northern s ies . They are composed Of - l t o stars , star clusters and nebu ae , and seem form independent systems outside o f the f greater universe o stars . On the opposite side of the pole from the Er i da n us Cross is the constellation , the north r Of hi o ur ern pa t w ch is to be seen in latitudes . ' ll nl Its most bri iant parts , however , are o y visible in the south . Its most brilliant star , Al A pha , is also known by the rabic name Of ! ! A n o f l cher ar , the end the river . Final y , A d between rgo and Eri anus is Columba , the

Dove , immediately south Of Lepus , the little e group b low Orion . A number o f these southern constellations A ur r such as rgo , Centa us , Lupus , and E idanus ha ve been known from prehistoric times ND L 0 A S . 1 1 SUN, MOON, P ANET but the majority have only been k nown a n d named since European civilisation reached the southern hemisphere . Considering the advantages Of later astronomers as compared with the circumstances o f the early star

o ur n - gazers who named orthern star groups , it cann ot be pr e t e n fie d that they accomplished their work satisfactorily ; fo r the southern ll n conste ations , speaking ge erally , are not only di ffi cult to identify , but are inappropriately a n named d grouped . The chief stars in the southern hemisphere are easily remembered , in the same way as those in the north—the Cross and Achernar are at di fie r e n t sides of the Pole so are Argo a n d r An d o f Sco pio . with the march the seasons i the r positions are constantly changing .

A T CH P ER V III .

S N M O ON AN D P L NETS . U , , A

WE have n o w discussed the various constella tions and the best method of recogni sing them and identifying their principal stars . These stars lie at immense distances from the Eart h they form the background of the motion s o f f e th e bodi es o the Solar Syst m . The ancient Greeks recognised seven bodies

AND L . 103 SUN, MOON, P ANETS

zodi acal constellation s such a s Taurus a n d mi n hi i n Ge i are gh the heavens , and others such as Scorpio and Sagittarius are low down a n d H not far above the horizon . ere , then , n we have the key to the seasonal cha ges . When the Sun in its apparen t path is in t h e hi gh constellation s o f the Zodiac it is summer the orb of day is high above the horizon and i s e o n visible for a protracted p riod ; when , the n d S o r s other ha , the Sun is in corpio Sagittariu i s sk i s it is winter . The Sun low in the y and r only visible for a comparatively Sho t time . When the brilliant conste llations o f winter o n m i dn i s are the meridian at ight , the Sun d e in the zo iacal const llations Opposite , namely , ! - a n d S the summer star groups , Scorpio agit t a r i us i n r . In summer the Sun is the winte n n t h e co stellations . The reason of this tilti g of ecliptic is the fact mentioned in the fir st f chapter , namely , that the axis o the Earth is di b ut not perpen cular to the plane of its orbit , n d - At incli e twenty three degrees . the spring x a n d ni l equino , in March , d—ay ght are equa all over the Eart h a t the poles and the A equator . t th is period both the poles are exposed to the S olar days in an e qual degree but with the gradual revolution o f the Eart h in its orbit the northern hemi sphere is in clined a n d more and more to the solar beams , the mi e southern he sphere less and l ss . Gradually 104 L S M PRACTICA A TRONO Y .

s At Spring pa ses into summer . the summer solstice in June the days are much longer tha n n m i the nights in the orthern he isphere , wh le in the southern the reverse state of thi ngs Af prevails . ter June the period o f daylight in the northern hemisphere gradually de creases until i n September day and night are equal all over the globe . The axis Of the Earth is again upright relative to the Sun ; the northern hemisphere is tilted more and more away from the Sun as autumn passe s wi into nter , until at the winter solstice it reaches its greatest inclin ation away from the sun - the reverse state Of affairs being the case A n in the south . fter the wi ter solstice the period Of daylight gradually increases , as the Earth is tilted more and more towards the n solar beams until the Spri g equinox in March , i when day and n ght are equal all over the globe . The result o f thi s cycle o f change is that in Spring and autumn the Sun rises due east and sets due west in summer it ri ses in the north

- east and sets north west , and is about eighteen — hours above the horizon just as is the case o f with the high constellations the Zodiac , Taurus and Gemi ni in winter it rises in the - - i s south east and sets in the south west , and above the horizon for a comparatively short o f lo w time , as in the case the constellations

d . of the Zo iac , Scorpio and Sagittarius 0 AND L . 1 5 SUN, MOON, P ANETS

so due i The sea ns , then , are to the nclination ’ u o f the Earth s axis . But another ca se is also i n d at work , though a very modified egree . ’ Th e ' Ea r th s b ut orbit is not a perfect circle , an ellipse therefore at one poin t o f its orbit a h i s n the E rt closer to the Sun tha at the other . In o ur n orthern winter the Earth is three millions of miles nearer than in summer . — H ere we have an apparen t paradox that the time o f closest approach to the S un is the time of greatest cold . When we consider the di s question , the apparent paradox soon m i e appears . In the northern he spher the lesser distance Of th e Sun modi fies th e rigours o f n i winter, and its greater dista ce m tigates the warmth of summer . In the southern o n n hemisphere , the other hand , the conditio s o Of are reversed . The peri d greatest heat di occurs when the Sun is at its least stance , and that of greatest cold wh e n i t is furthest away . Thus the climate in the northern hemisphere is rendered more equable than that in the southern . To the Observer without a telescope the Sun can scarcely be described as an interesting

c . n Obj e t Whe spots are numerous , at the

- sun ! spot maximum , the larger ones are some times vi sible to the unaided eye through i o f - o smoked glass . But the v sibility sun sp ts to the unaided eye is a very rare occurrence .

10 AND L . 7 SUN, MOON, P ANETS A new Moon and full Moon . t full

!

Moon the Sun , the Earth , and the Moon are in n mi a straight li e , with the Earth in the ddle n o n position . The Sun is shi ing directly the o se e d l Mo n , and we it fully illuminate , whi e ! at last quarter only half o f the Moon i s l il uminated , as seen from Earth . O win g to its eastward motion along the di n 50 Zo ac , the Moo rises about minutes later h i o f each day . T s is the average amount delay , but the amount varies ; sometimes it is less than half an hour , sometimes an hour di f n o n and a quarter . The fere ce depends the angle which the Moon’ s path makes with the horizon this angle is least i n the constellation

n . H n Pisces , visible in autum e ce we have the ! n o f H phenome on the arvest Moon , when o ur satellite rises less than half an hour later i n every even g . There is much less moonlight in summer At hi than in winter . first t s may seem to be due to the length ened period o f daylight the moonlight n o t being required a n d con sequently not noticed ; such , however , is not nl the case . There is really less moo ight in n summer than wi ter . This arises from the fact that before the Moo n can be full and shining with complete radiance , it must be i n t o opposition the Sun that is , situated o f sk in the diametrically opposite region the y . 8 AL 10 PRACTIC ASTRONOMY .

I n winter the Sun is passing through the lower d n zo iacal co stellations , consequently the Moon at the full phase passes through the higher . The full Moon at m i dwinter is in the same m situation as the Sun at idsummer . Thus in n n wi ter there is more moo light than sunlight . n n di I summer the co tions are reversed . The Sun is in the higher con stellati ons ; co n se quently the full Moon at m i dsummer occupies m i the place Of the Sun at dwinter, and thus there is more sunlight than moonlight . The Moon may be studi ed by means o f the binocular , and even in a small telescope it is a wonderful spectacle . The full phase o f the Moon is the most useful to mankind , but it is not the most interesting n At i s to the astro omer . that phase the Sun ni o n a n d n shi ng direct the Moon , conseque tly the Objects Of the lunar surface cast no Shadows . A view Of the full Moon i n a telescope is di s A ti n ctly disappointing . few days before the ul full phase usef observations may be made .

The astronomer , however , studies the Moon at all its phases ; in fact , it is only by long continued Observation that anything can be learned concerning our sa tellite . When o n e looks at the Moon through a — a — telescope large or sm ll for the first time , the most stri king feature is the r ugged and mountainous character o f the lunar surface . AND L 109 SUN, MOON , P ANETS .

The surface is diversified by great grey plains , hi w ch were once supposed to be seas , and n o f mountainous uplands , comprising ra ges hills and mountains , and great numbers Of n h walled plai s and volcanic craters . T ese volcanic craters are by far the most numerous n objects o the Moon . Volcanic action seems to have been much stron ger o n o ur satellite — H o ur to . than Earth relatively Size owever , this action seems to be now practically extinct , and the Moon i s generally beli eved to be a dead ’ world . Professor P ickering s studies indicate the possibility that a very thi n atmosphere does exist , and that there is a rudimentary

. so vegetation But , even if this be , we are correct in regardi ng the Moon as dead . — Th e Plan ets There can be little di fficulty n — in identifying the principal pla ets Venus ,

Mercury , Mars , Jupiter , and Saturn . Of the seven chi ef plan ets of the Solar System outside o ur o wn nl fiv e Of world , o y these are visible d to the unai ed eye . Uranus is practically e invisibl without the aid Of a telescope , and S Neptune absolutely O . Absolutely the larger plan ets are di vided into two groups according to size—the Inner

Planets , comparatively close to the Sun , Mer cury , Venus , the Earth , and Mars , compara ti v e ly small in size and the Outer Planets ri n o f — beyond the g minor planets Jupiter,

AN L D . 111 SUN, MOON, P ANETS

planets and their motions among the stars . These motions are much less Simple than those n d f Of the Sun a Moon . The motion o the Sun along the ecli ptic is simply the Earth’ s motion ’ reflected in the heavens ; the Moon s circuit o f the Zodi ac i s simply the actual revo lution

o f the Moon round o ur world . But the planetary motions are a combination Of real

and apparent movements . The Earth is a r planet , and in motion ound the Sun ; the n H planets are also moving round the S u . ence ’ the Earth s motion i s partly reflected in the

irregularities Of the planetary motions . Thus the planets are sometimes apparently moving from west to east ; sometimes from east to w st a est . Sometimes they appear almost f n ti o n a r . o y It is , however , no part our prese t purpose to enter into a discussion o f the n pla etary motions and their irregularities , whi ch have attracted the attention o f astron ll omers and mathematicians in a ages . Venus is the most brilliant pla net the n evening star and the morni g star , the H esperus and Phosphorus of the r Greeks . F om very early times the identity o f the morni ng star and the evening sta r h a s n been recog ised . The late Professor Schia pa r elli suggests that it was recogni sed so long ago a s the epoch o f the Book o f J o b he be li ev e s Mazzaroth in its season to refer to 112 L PRACTICA ASTRONOMY .

i n n the period cal appeara ces of Ve us . Be thi s a s it may , the motions of Venus have been li fami ar to mankind from the earliest ages . Venus is said to be at superior conjunction S un a n d when the Earth , the , Venus are in

i . a straight line , with the Sun in the m ddle ’ Venus , owing to its position within the Earth s hi a n d orbit , ex bits phases similar to the Moon , m i at this time it is fully illu nated , but is lost f in the rays o the S un . Then the planet ! n emerges from the su light as evening star . When it reaches the position known as great o f di est elongation east the Sun , the sc seen through a small telescope is fully illum i nated A n like the Moon at the quarters . S Ve us draws nearer to the Earth the di sc increases mi in size , but the illu nated portion decreases — until the planet n o w a dwindlin g crescen t is again lo st in the rays o f the Sun at the posi ! f ! hi tion known as in erior conjunction . T s ! position is analogous to new Moon . The d planet is invisible , as its dark side is turne towards the Earth . Shortly after this it reappears a s a morning star it is at first n a thin crescent , increasing in size u til it reaches the position known a s greatest ! i s elongation west . It now at its best posi f n i tion o r observation a s a mor ng star . Seen through the telescope the di sc becomes sma ller and more fully illuminated , until it again A D L » N . 113 SUN , MOON, P ANETS reaches superior conjunction , and is lost in n o n un the solar rays . The i terval from c j c

— . tion to conjun ction superior conjunction to n o r superior conju ction , inferior to inferior 5 84 a n d c is days , is known as the synodi period of Venus . a n d Venus at times is exceptionally brilliant , the ignorant have from time to time regarded the planet as a return of the star o f Beth ! f h e o r . o t lehem , as a portent The phases

l , p anet are not visible to the unaided eye , but

. may be seen In a small telescope . These phases were discovered by Galileo three centuries a g o , - AS with the newly invented telescope . a tele scopic spectacle Venus is o n e Of the most ex ui site i ts k q in the heavens , but owing to thic d f o f e atmosphere and the if iculty obs rving it , o f little is known its physical constitution . . ' Mercury passes through the sa me series Of a s S i changes Venus in a horter time , its synod c 1 1 ri 6 . n pe od being days Like Ve us , Mercury hi e ex bits phases , but these are not visibl r in the smallest telescopes . Mercu y is very di f n o l ficult Of Observation , and it is smal tribute t o the Skill and perseverance Of the prehistoric astronomers that Mercury was s known in those early times . The planet i nl e never far from the Sun , and can o y be se n r at its elongations as morning o eveni ng sta r . ‘ di fii cult to Even at these periods it is Observe , 8

AND L . 115 SUN, MOON, P ANETS

u— 3 99 o f 3 78 sitio is days , and Saturn days . Off i s Thus the farther a planet , the shorter is i t s synodi c period . With Mars the case is di di 7 80 fferent the syno c period is days , over two yea rs . Mars is much closer to the Earth t e a n d n han Jupit r Saturn , and its appare t f . o motion is more complex Oppositions Mars ,

i n ill . Of too , vary greatly br iance The orbit Mars i s very elliptical in comparison with other f planetary orbits . The pathways o Mars and the Earth approach nearest at the point o ccu Of A pied by the Earth about the end ugust , and they di verge most at the point occupied

‘ r H by o u world in February . ence when Mars i s in Opposition in autumn it is very bright , i s and in spring much fainter . This , however, somewhat modified by the fact that in spring di the planet is in the high zo acal constellations ,

- and in autumn in the low star groups . Favour a nf c able Oppositions , and lso u avourable , re ur at intervals o f about fifteen years . Thus there were very favourable oppositions , when the wa s 1 877 1 892 planet very brilliant , in , , and 1 907 nf 1 886 , and u avourable appearances in , 1 901 1 9 1 6 , and . A small telescope will Show the satellites Of h a s Jupiter and the ring Of Saturn . It been a lleged that the sa tellites o f the former planet e have be n seen with the unaided eye , but the l e vidence is far from conclusive . In a smal 1 16 L PRACTICA ASTRONOMY . e a n d t lescope , however , they are easily seen ,

. A l form a beautiful , telescopic spectacle smal instrument will , however , Show no features o n Mars ; a good telescope is required to - hi Show the surface markings , w le the famous canals are only to be seen with powerful i instruments in favourable cl mates .

A T CH P ER IX .

R N M I AL P H E M E A S T O O O N O NA .

U ND ER the head of astronom i cal phenomena we inclu—de occurrences and appearances in the heavens eclipses of the Sun and Moon , tran sits Of Venus and Mercury , comets , meteors , A di . the zo acal light , and the urora Borealis Such appearances attract a large amount o f — attention more , perhaps , than is their due . — Ecli pses a n d Tran sit s These kindr ed phe n o m e n a are due to the fact that every body in the universe Shini ng by reflected light casts a shadow into Space in a direction opposite to the source o f illumination . Thus the Earth casts a shadow , and similarly Venus , Mars ,

Jupiter , and the other planets cast shadows . The shadows cast by the Earth and the Moon are the cause o f the phenomena known a s solar and lunar eclipses . The Earth casts a L ASTRONOMICA PHENOMENA . 1 17

S hadow , and when the Moon , the Earth , and S un the are in a line , with our world in the m i dl ri d e , the terrest al Shadow which extends ' beyond the orbit o f the Moon falls in the di f ur f rection o o satellite . If the pathway o the Moon were exactly in the same plane o r o f o ur level as that world , it would pass through the Shadow every time it reached the position known as full Moon . ’ AS o f a matter fact , however , the Moon s o rbit is not exactly in the same plane as that o f t h e t n i Ear h , and only occasio ally an ecl pse a do es t ke place . Sometimes a lunar eclipse is — I s sa total that to y , the Moon is completely immersed in the Earth ’ s Shadow—and some a o f d r e times only partial , portion the isc ni A mai ng outside the true shadow . total eclipse o f the Moon is a very remarkable and As beautiful phenomenon . the Moon becomes i gradually immersed in shadow , the illum nated portion becomes smaller and smaller until it

c . ompletely disappears The Moon is not , how l ever , usually totally invisible . It genera ly O - e h u assumes a dark opper colour d e , due to the refraction o f sunlight through the atmosphere o f i the Earth . Th s is supposed to be due to the fact that the blue rays o f the Sun a r e absorbed in traversing the atmos phere o f the

Earth , just as the sunset and sunrise skies assume a ruddy colour .

1 19 ASTRONOMICAL PHENOMENA . o f A At o f an merican astronomer, the end this period the centres of the Sun and Moon return very nearly to their relative positions at the beginning o f the cycle ; also certain technical conditions relating to the Moon’ s orbit and essential to the accuracy of the sa ros ! are fulfilled . Thus a tota l solar eclipse took o n 1 7 1 882 o n 2 8 place May , ; it recurred May , 1 900 8 1 9 1 8 o n . ; and again June , Eclipses , o n a o f however , do not recur the s me part the Earth’ s surface hence at any given place li total solar ec pses are very rare . There has n o t been a total solar eclipse in the United 1 72 4 ll o n e Kingdom since , and there wi not be 1 92 Fo r r visible until 7 . those who have neve a n seen a tot l eclipse , the following descriptio A t h e . by an merican writ r , Mrs Todd , is wor a s ni o f reading , illustrating the mag ficence the spectacle With frightful velocity the actual d o f e sha ow the Moon is often s en approaching , a tan gible darkness advancing almost like a Th e a s a s . wall , swift imagination , silent doom immensity o f Nature never comes quite so near a s to then , and strong must be the nerve not quiver a s this blue- black shadow rushes upon th e spectator with incredi ble speed . Some times the shadow engulfs the observers smoothly , sometimes apparently with jerks ; but all the world mi ght well be dead and cold t s and turned o ashes . Often the very air seem 1 20 L MY PRACTICA ASTRONO . t o hold its breath fo r sympathy ; at other times a lull sudden ly awakens into a strange w a ff o ut ind , blowing with unn tural e ect . Then u pon the darkness , gruesome but sublime , fl o f ashes the glory the incomparable corona , S a ilvery , soft , unearthly light , with radiant s i o f um treamers , stretch ng at times millions c i omprehended miles into Space , wh le the rosy flaming protuberances sk irt the black rim o f t h e Moon in ethereal splendour . It becomes c uriously cold , dew frequently falls , and the ll chill is frequently mental as we as physical . S nl udde y , instantaneous as a lightning flash , a n arrow o f actua l sunlight strik es the lan d s cape , and Earth comes to life again , while corona and protuberance melt into the return ! in g brilliance . n dr Transits are ki ed phenomena to eclipses . O s nly the interior planets , Mercury and Venu , r a e to be seen in transit across the Sun . Tran ' o ur occur , like solar eclipses , when world , .sits o r o ur Venus , and the Sun , world , Mercury , a n d the Sun are in a straight line . There is n o n S eclipse , owi g to the mall apparent size of M ercury and Venus we merely se e black discs f a s spots crossin g the face o the Sun . o f e Transits Venus occur in pairs , separat d b y intervals o f eight years and the pairs are 2 1 s eparated by intervals o f 105 5 a n d 1 5 years . 1 6 3 1 a n d 1 6 39 1 76 1 There were transits in , 12 ASTRONOMICAL PHENOMENA . 1

1 76 9 1 874 a n d 1 882 a n d and , ; the next pair 2004 201 2 o f will take place in and . Transits

Mercury are much more frequent . — Co m et s a n d Mete ors These kindred celes tial bodies have attracted the attention o f A mank in d from the earliest ages . mong the ancients and to the peo ple of the Middle Ages o f comets were a source terror , and were o f believed to be terrible portents wars , fam d di a n . ines , other national sasters In the present day these feelings have given place to won der a n d admiration . O f all celes tial phenomena , comets attract the great o ur est and most wi despread attention . In present knowledge we may divide comets into two classes— those which have been proved to revolve round the Sun a n d wh ose n ca n di a n d t retur s be pre cted , those come s h n which ave not been demo strated . to be ’ members o f the Sun s family . To the first o f H class belongs the famous comet alley , whose last appearan ce i n 1 91 0f ell so far short o f popular expectation ; a n d also the faint o f ' hi h r comet Encke , w ch returns every t ee o f di years , and others . Most the perio c n a n d comets are fai t , do not attract atten tion even when visible to the unaided eye . Th e 1 8 1 1 1 843 1 85 8 brilliant comets of , , and , a n d o f other notable comets the last century , may o r may not belong to the Solar System ;

L ASTRONOMICA PHENOMENA . 123

favourable time for observation than from dn sunset to mi ight . The explanation is that more mete ors meet the Earth than overtake it , and as Mr . Maunder remarks the Earth has its sunrise point in front a s it moves fo r ! i n i ts ward its orbit , sunset point behind . Th e Zo dia cal Lig h t - This is a phen omenon whi ch is much better seen in tropical than in e n o h t mperate regions , but it is occasio ally n A served i Europe . pearly glow i s sometimes noticed in the sprin g to Spread over a portion o f sk the y where the Sun has disappeared . In autumn the same phenomenon is also to be i n seen before sunrise . It is tropical regions ,

i ts . however , that it is seen in full glory n o f o ur I stead being seen like a cone , as in o f latitudes , it appears as a band light , and the portions near to the Sun seem as brilliant as f i the Galaxy . The exact nature o the zod acal o r light has long been more less of a mystery . The general idea among astronomers is that to di f l it is due f used dust , in all probabi ity meteoric matter which forms an outer append to age to the Sun . Opposite in the heavens the Light is a much fainter phenomenon known ! o f o r by its German name the Gegenschein , - o f e r counter glow . Probably it is also met o ic s compo ition . Th e Aur ora B or ea li s n . This phenomeno , closely connected with the magnetism o f the 124 PRACTICAL ASTRONOMY .

. o n e o f th e n o f Earth , is most striki g celes

. n tial spectacles Properly speaki g , the aurora should perhaps be classed among atmospheric it s n phenomena , but close co nection with the sun -Spot period renders it more di rectly akin to the heavens proper . A — h i t s —The urora Borealis t e Northe rn L gh i s a regular phenomenon in the Arctic e a n d t r gions , is often visible in the She o f lands and Orkneys , the north Scotland , and Northern Europe . In lower latitudes the aurora is a rare spectacle , and attracts f a great deal of attention . It consists o s o f streamers , band , curtains , and rays light o f varying tints and di fferent degrees o f bril l n n i a cy. These tremble and shoot up and dow the sk y with startlin g effect hence the popular f — f ‘ ! name o the aurora the Merry Dancers . In lower latitudes aurorae should be looke d fo r more particularly when Spots are numerous di o n the solar sc . Great storms in the Sun a r e generally accompanied by magnetic di s t ur b a n ce s and bri lli ant auroral di splays o n the o f n h a s n o t Earth . The nature the co nection o f I s bee n fully explained , but its reality there no doubt . In thi s ch apter particular attention h a s been given to these astronomi cal phenomena which — are o f comparatively rare occurrence the o f ri e di s a ppearance b ght comets , met oric L 2 ASTRONOMICA PHENOMENA . 1 5

o f S un a n d plays , eclipses the Moon . These phenomena never fail to awaken the curiosity

o f - and interest the average man . It is well that they should ; and yet it is necessary to n r e remember that wo derful as are eclipses , s markable as are meteoric Shower , far more e o r wonderful , far mor marvellous are the di n a r y facts which astronomy teaches us , far more awe-inspiring is a thoughtful glance into the immeasurable heaven s . The marvellous a n d o f - li power energy the Sun , the never fai ng regularity of the Moon a n d planets in their a eternal revolution , the vast dist nces and ni o f n spaces , the calm Shi ng the cha geless stars -these are marvels visible t o us daily and nightly , and we heed them not . Familiarity to i n gives rise , if not to contempt , at least difference . AS Emerson has truly said If the stars should appear o n e ni ght in a thousan d h o w i a n d a a n d years , would men bel eve dore , preserve for many generation s the remembrance ! o f i the City of Go d wh ch had been shown .

I N D E ! .

A LOOR, 28. Al o n e cy , 46 . o r o n a o re a C B lis, A de ba ra n 7 21 44 45 53 64 o r vu 60 l , , , , , , , C s, . 6 6 99. r a te r , C , A Fa r d 6 l , 1 . r o th e So t e r n 96 9 C ss , u h , , 8 . l o 0 A g l , 5 , 51 91 . n 84 , Cyg i , 85. Alta i r 8 , 7 . n 8 19 81 83 85 98 Cyg us, , , , , , 87 , . n der o n T A s , . D 52 . D ELP An dr o m a H IN US ed , , D e n eb 84 An ta r es , . , 77 . D e n n n W F a r i g , . . 122 . Aq u ius , D r a o 8 A u a 9 81 86 c , , q il , 7 , , , 87, 88. D o n S i r F W A r a ys , . . 22 . , 96 . , Ar ct r 66 6 7 68 69 . u us , , , , E RTH 10 A , , 11 , 13 14 15 20 21 Ar o Na v 97 98 99 , , , , , g 100 101 . is , , , , , 81 Ar e 19 9 02 , i s, , 1 , 1 . A r a 33 3 u i , 7 47 . g , , 118 1 24 . A r o r a o r ea 1 , u B lis 1 6 123 . , , E e 116 117 clips s , , , Eddi n to n A . S . B g , , ALL S i r R. S 80 , . E n lki , W a r n a r d E E . . 75. B , , Em e r So n W , R . . 125 . e a tr , B ll ix 41 . , En e J F ck , . . 121 . e te e x , g , 45 B l u , Er ida rius 4 91 100 , 7 , , .

oo te 8 64 FLA M B s M ARI ON C . , , , , , Fo m a lh a ut 90. CANOE GALA! Y th e 22 30 6 0 64 65 a n e e n a i , , , , , , , s t ci 62 . C , 88 a n Ma o r , is j 21 38 . C , , 96 98 99 1 3 2 . a n M n o r 43 , , , C is i , . a eo 1 13 . a n o G lil , C pus, e m n G i i , a e a 32 33 54 64 C p ll , , , , , 1 04 . a r o r n 88 89 p ic us , 102 . C , , o o d ri ck, J . 51 . a r e T G , C lyl , . , 8. o r E . e J . 50 65 a s o e a 29 30 31 32 G , , , . C si p i , , , , , 34 52 95 , , . H AL E . E 12 , G . a sto r 46 , 47 . Ha l e E 2 C , . 1 1 l y, . Ce n ta ur i A1 h , a , 20, e n de r o n H s , T. , 97 . C e n ta ur ris 2(p97 Her les 71 2 3 4 , cu , 7 7 7 75 94 . , , , , , e e 34 ph us, 35 . H e r e S i r C J . sch l, , 99 . e r e 15 C s, . He r e S i r W sch l, . , e t s C u , H es o d 1 25 4 i , 7 , , 5 . o ma e re ni es 6 C B c , 2. Ho me r 42 , . o m e ts C . H a de th e 44 y s , , . o er n u N p ic s, . 114 . H dr a 6 1 65 C , . y , , 128 ! INDE .

I NNES R . T 98. r . Pr to R . 85 , A o c , A , . r o o n 42 6 P cy , , 43 , 4. B 1 25 4 4 J O , 7, , 2 , 5. te r 11 15 1 1 2 02 REG L S 56 J upi , , , 7, 8, 3 , 1 , U U ,

109 1 4 1 R te r J . P 24. , 1 , 1 5. ich , R e 40 41 43 47 54 64 66 ig l , , , , , , , .

A E . 22 K P T YN, J . C , ’ ‘ S AGI TI A , 87 , 94 . LEO 6 55 56 57 62 63 65 96 — , , , , , , , , , Sa tta r 6 102 104 . g i ius , 7 , 78, 88, 2 10 . a 1 S r o s , 1 8. 38 4 100 Le pus , 7 , . n 2 4 1 1 , Sa tur , 1 5, 10 , 109 , 11 , 5.

L b ra 76 102 . i , . 11 , Schia pa r e lli , G . V , 14 , 1 .

w P 1 4 . Lo e ll , . , o r o 6 8 88 6 Sc pi , 38, 7 , 77 , 7 , , 9 )

96 100. Lupus , , 101 1 10 10 , 02 , 3 , 4.

9. Lyr a 33 , 7 r n 1 5 , Se pe s, 7 , 74 , 7 . 87 . r v 6 Se iss , G . P . , 9. MARS 6 11 13 14 18 102 , , , , , , 77 , , 2 3 . Sha ple y , H . , 7 , 7 109 1 14 1 15 116 . , , , e e 23 Sh ll y , P . E. , . Ma n de r E . W . 5 19 30 56 u , , , , , , 9 21 64 Sir ius , 7 , 17 , 1 , , 43 , 53, , 69 , 90, 123. 6 6 , 97 Me r r 1 1 13 102 109 110 cu y , , , , , , h e 1 16 1 So la r Syste m , t , 1 , , 7 , 1 12 1 1 3 120. , , 1 8 19 22 23 41 42 85 101 , , , , , , , , Me te o 16 5 121 122 123 . r s , , 7 , , , 121 . x Milky W a . S ee a la y . y G S a 5 pic , 8, 64 . r f M a 50. i k , 24 40 S un th e , 10 12, 16 , 21 , , . za r , , Mi , 28 . 41 3 81 85 102 103. , 4 , 56 , 69 , , , Mo n ta n a r 51 . i, 10 110 1 11 4, 105, 108, , Mo o n th e 5 10 13 16 20 23 , , , , , , , , 1 01 06 10 111 , 102 , 1 , 7 , ,

1 16 1 1 118 119 120 1 25 . TA R S 21 44 48 95 102 103 , 7, , , , U U , , , , , , , 10 4 . ’ ‘ NEP I U NE 1 1 15 110. , , , e n n o n A 44 54 . T ys , . , ,

Ne o 80. w mb S . c , , To dd , M r s , 119. No v a i 88 . P e r se , 87 , r a n m 94 . T i g ulu ,

T o r 32 . OP H I ych B a he , CH S 1 4 . U U , 7 , 7 Or o n 7 8 18 37 38 39 41 43 i , , , , , , , , , U RAN S 1 1 15 1 10. U , , ,

45 6 9 94 96 . 44 53 54, , 77, , U r r 2 2 , , , sa Ma j o , 5, 8. U r a M n o r 29 . P EGAS S 92 93 96 s i , U , , , .

Pe r e 35 3 49 50 52 95. 9. s us, , 7, , , , V EGA , 32 , 33 , 35 , 66 , 68, 7

1 109 . 110 P e r n W H . 4 V 2 102 109 ick i g , . , , e n us , 11 , 13 , 3 , , , ,

P e 89 90 102 . isc s, , , 111 , 112 , 113 , 120.

P e a de 18 45 62 . V r 6 5 96 102 . l i s , , , i g o , 6 , 58, 6 2 63, , , P o th e 8 25 26 27 28 V o e H 51 l ug h , , , , , , , g l , . C . 2 32 45 55 9, 30, , 33, 34 , 35, , , W OLF, M 15 . 63 . , 67 , 95

Po e ta r th e 28 30 35 95. ZOD I AC 96 102 1 03 104 107 l S , , , , , , , , , , .

x 6 11 1 1 14. Po llu , 46 , 4 . ,

P e Zo d a a L t th e 123 . ra e s pe , 62. i c l ig h , ,

P RINTED I N GREAT B RITAIN AT

TH E P RES S OF TH E P UB LIS H ERS .

University 0! Toronto library

DO NOT

REM OV E

CARD

FROM

THIS

POCKET

Acm e Li b r a r y C a r d P o ck e t

- LOWE M ARTIN C O. LIM ITED