IN STARRY SKIES

Evening Post, Volume CXIII, Issue 2, 4 January 1932, Page 14

IN STARRY SKIES

, SCORPION, SERPENT BEARER, ALTAR, AND RULE

(By "Omega Centaun.")

The Scorpion is certainly one of the '{most beautiful of tho constellations. Its only rival is Orion, and the two may ■well be allowed to share the honour. £Tot only do these two surpass all other groups in beauty, they aro also the easiest constellations to recognise, ex-cept:-perhaps the Southern Cross with the Pointers. In learning the constelJations, anyone in the Southern Hemisphere- should start with these throe groups. In New Zealand tho Pointers and tho Southern Cross iic\cr set, and we can always see either the Scorpion or Orion. Delta, in Orion's belt, Is almost On tho equator and therefore ds above the horizon for twelve hours at a time. Botdlgeuse ciosses the meridian almost exactly twelve houis before lota in tho sling of tho Scorpion. But the bright stars of tho Scorpion range from twenty to foity-iivo degrees in southera declination, and so are in view for fromr fourteen to twenty honrs at » 'time. Thus it happens that Orion rises before the Scorpion sets, and the latter appears again over the soutli-cast-*Mn hills when Orion is sinking in the west. The rising of Orion in the early evening wo associate with the begin-

aiing of spring, and the Scorpion in a similar way is the herald of Easter.' The same *iirce constellations are useful jn defining the position of ,tho Milky iWay, which passes close besido Orion smd right through the othei; two. As | «, wido stream it passes between Proc'yon, on one side and Betelgouse and I SJirins on the other. Its narrowest point I ft reached just before it envelops the Cross. The Pointers also aro in the Middle of it, and then the stream gradually widens until, on reaching the Scorpion, it extends right from thel Claws' to the Sting. This fact gives' these constellations an added import-1 ancc. "When the Southern Cross is at its lowest point, directly below tho pole, the Milky Way encircles the horizon and becomes almost unnoticeable. .This occurs- in the early evening in October and November. Orion is then rising and the Scorpion - letting. In February and March, and again in.June and July, the Milky Way passes right | overhead, in the former case from' W. to S.E., in the latter from. N.E., to S.W., ,and beween those dates it is: high in the .sky. It is thus only'during I tho first part of the summer that the Milky Way fails to be conspicuous in the early evening sky. Fortunately we | Tiave no scorpions in New Zealand, and no one is tempted to introduce them, so we cannot say that -we are reminded of them, by this curved line of stars. But the arrangement, is so striking that it gives a suggestion of life and activity. Occasionally this group has teen taken, to represent a snake or a Crocodile, but it was known as a Scorpion to the Arabs, the Persians, 'the Greeks, and the Romans. The Greeks said it was sent by Diana to till Orion, Tmt the Romans made Juno the instigator of this crime. Antares, the brighest star in the Scorpion, is a most remarkable bbdy. "Its ruddy colour is very noticeable even 1o the naked ej-e. Tho Chinese in the '-days of Confucius called the constellation the Great JJire. Great, indeed, is ■the. red fire of A'ntares. The star heads •the list of known giants with 'a diameter 450 times that of the, sun, ,or nearly 400 million miles. Its volume must be equal to that of 90 million «ut(S,-but it is so tenuous that its mass is only 40 or 50 times thnt of the sun, and it outshines the sun somo 400 or 800 times. It is 125 light years from ss. Antares probably got its name, "The Rival of Mars," from its ruddy fcolour. It is a visual TrinarVj the com-

panion being of the seventh magnitude and only 3.5 seconds from it. The main star is :morcover a apeciroscopic binary.

Near Antarcs is M.4, a globular cluster of a great number of very faint stars. Thirty-three variables liavo been discovered within it. It ij ono of the nearest globular clusters,, being about 23,000 light yeais away. M.62, M.SO and 6441 aro albO globular clusteis, at distances of 60,000^57,000, and 69,000 light years respectively. Twenty-six variable stars have been discovered- in M.62 and f our -in- M.BO.

M.6 and M^7 aro much nearer and smaller groups of stars. Shaplcy clas'sines- them as galactic clustois, each lof about DO stars, and gives their dis--1 tances as approximately 1400 and 1000 light years. The stars in M.6 are | strangely arranged in lines •which suggest an outline di awing of the petals of a flower. i Serpens and Ophiuchus foiin a vast, but not very striking, double or interlaced constellation. It extends from 25 degrees noith to over 30 degiees south of the equator, and through four hours of right ascension. Tho northern portion -was shown in an earlier map. Tub whole constellation contains about sixty nalcod eye stars, but none brighter than tho second magnitude. They aro arranged in lines crossing one another, and this may have suggested the idea of tha Serpent Bearer. Tlic head of the Serpent is marked by a ?roup of stars, Beta, Gamma, Kappa, la-i, and many fainter ones lying in 'tho region near Arturus and tho Northern Grown. The line of its body is marked by Delta, Lambda, Alpha, Epsilon, Omega, and Mu. Near the latter it disappears be-

hind the<,body of Ophiuchus. It reappears again, twenty degrees away, in. Nu, Xi, Omicron, and Eta, and extends to Theta right on the borders of the Eagle. Tho head of Ophiuchus is marked by the second magnitude star Alpha, which is close to Alpha llereulis. One foot, represented by Phi, Chi, Psi, and Omega, reßts on the heart of the Scor-pion,-near Antares, the other, marked by, Theta, reaches nearly to the Scorpion's Sting. M.O, M.lO, M.12, M.14, and M.19 are all globular clusters. Their distances range from 36,000 to 68,000 light years. M.S, in Scrpens, lies just north of the equator. It is one of the brightest of the globular clusters, -being surpassed only by Omega Centauri and 47 Toucani, and equalled by M.22. No less "than 84 yar" ; iables haye been disco vered "In. 'it.,lts distance is over 35,000 light years. Ara, the Altar, is a. small' constellation between tho sting of the Scorpion anil the feet of the' Centaur. It is one of the ancient groups, but is just on the border of Ihe region hidden from the astronomers of antiquity. 1 About twenty of its stars, are visible to the naked ,eye, but none are" very bright. Alpha is of the second magnitude, and Beta is a ah'ade brighter. Tho globular cluster 6388 is small, but>. fairly distinct. It"is from 56,000 liglit years away. No. 6397, at a distance of 18,000 light years, is one of the very nearest, globular clusters. Hence it appears considerably larger and much brighter. Norma, the Rule, is a small 'constellation added by La Caillo in 1752. He gave it the more imposing but clumsier name," Quadra Euclidis, or Euclid's Square. It extendd about 23 degrees from north to souta, and about 10 degrees from east to west in its widest part. It has less than a dozen stars visible to the naked eye, and all of these are below the fourth magnitude. It contains three interesting galactic clusters, janging, in apparent diameter, from ten to twenty" minutes of arc. They are numbered 6025, 6067, and GOB 7in the N.G.C. They contain 30,120, and 35 stars" respectively, and their distances from uS-are about 1500, 5000, and 3,000 light years respectively. It is interesting to notice how much smaller these- distances are than any given, for globular clusters. It seems likely that any globular cluster which enters tho galactic stream is scattered, and thus loses its symmetry aftd apparent com-1 pactness. ' i