IN STARRY SKIES

Evening Post, Volume CV, Issue 147, 23 June 1928, Page 26

IN STARRY SKIES

. (By "Omega Cent.iuri.")

PEGASUS, THE FLYING HORSE

Near Young Andromeda .... Closo ifiid above her head tlio wondrous slecd With hoof and \yinls exerts a double speed. So close they meet, ,0110 brilliant star they . share,.' His body it adorns—and decl;s her hair. His side and shoulder with three others grac'U, As if by art at equal distance plac'd— Splendid and large. Obscure his ample chestBlack his long neck, and black his flowinf: crest. ' . . . But on his nostril clows a living fire— Snorting he seems to stamp with rage and ire. 'No quadruped tills horse; for lost to sinlit Vanish his hinder parts in darkest night.. Once as they say, on Helicon was seen • Starting from roclsy cleft sweet Hippocrene; When with his hoof he struck the sounding rock And earth, obedient to the magic shock, . Pour'd forth her copious stream. And hence . the name Of Hippocrene—and hence its lasting fame. ■Still flows tho. cooling fount in Thespian Treads Pegasus tho elysian fields of Jove. . . —Aratus. The Great Square of Pegasus fills a large space amongst the constellations tjest seen in spring. Only those who are up long after midnight or before the dawn see it now, but by the beginning of September it will be up in the early evening. Before the end of October it will be due north before' 9 o'clock. It is not a perfect square, for. as we see it the upper side is longer than the lower, and tho latter is longer than either of the other two sides, but it is quite a fair .approximation. It may well be called great, as its shortest side is about 13 degrees and its longest one 17. The four stars are fairly equal, all being between the second and third magnitude. 'As Aratus pointed out, one star does double duty, being Alpha in. the constellation Andromeda and Delta in that; of- Pegasus. It is the brightest star in the group, being of magnitude 2.2, and is known by the name Alphareto. The chief stars of Pegasus are arranged in a figure that is extremely like, though much larger than, the group ■of seven stars known as the Dipper in Ursa Major the Great Bear. A line of three stars extends westwards from Alpha Pegasi and corresponds to the handle of the' Dipper. :■ The name Pegasus seems to imply

great strength. The constellation was .|jrobably recognised as a. striking group in very early times, for a horse's figure with wings is shown on Babylonian tablets. This combination of strength and speed may have been used by the Ar,gans to represent Asva the Sun.- The best known stories of. Pegasus, however, wo owe to the Greeks, many of whose myhts are pictured in the sky. Cepheus and Cassiopeia, Perseus and Andromeda, Pegasus and Cetus, are all connected by -these old stories. Cepheus and Cassiopeia were King and Queen of Aethiopia. Andromeda was their beautiful ■daughter. The sea-nymphs were enraged by hearing Cassiopeia claim greater beauty than their own. They sent a sea monster, Cotus, to ravage tho coasts, of their kingdom. The unhappy monarchs were informed that their country could be saved only by giving their daughter Andromeda as a prey ro the monster. Poor Andi'omeda was chained to a rook, but before tho monster could get her, a hero appeared to rescue her. This wa3 Perseus, who was just returning from his victory over Medusa the Gorgon. He carried the terrible head decked with vipers instead of hair, which turned to stone all who saw it. Andromeda was warned to turn her face away whilst the sight of Medusa's head- turn.cd the sea monster into a mighty rock. But what has this to do with Pegasus? The connecting-link.is found in Bellerophon, the son, of "Poseidon, the God of the Sea. It is possible that he was originally identical with Perseus. Both wore connected with the sun-god' Helios and with the sea-god Poseidon, the symbol of whose union was Pegasus, the winged horse, renowned x for strength ;and speed. ' Perseus was the local hero of Argos, Bellerophon that of Corinth. Rivalry led to invention of fresh exploits. Pegasus, the white-winged steed, is said to have sprung from the blood of Medusa. He was caught and tamed by Bollorophon, who rode him when he slew the Chimaera, the storm-demon who devastated' the country. After many exploits Bellerophon attempted to fly to heaven, but when Jupiter caused an insect to sting Pegasus, he was thrown off, and the magic steed reached heaven alone. So, unless Bellerophon is represented by the constellation Perseus, he is absent'from the sky. The identity of the two heroes is; also suggested by the'later myth which declares that Pegasus was the steed on which Perseus. carried Andromeda away. But though Pegasus is enshrined amongst the stars ho has left his record on the earth. Wherever his foot struck fountains are said to have gushed forth. The famous ■ spring on-Mount Helicon in Boeotiais called Hippocrene, the fountain of the hovae; But it is also called the fountain of tho Muses, and was considered the source of poetic inspiration. It was jiot the only spring in Greece which, according ■to the legend, was produced by the stamping of the hoof of Bellerophon Js horse. Another was Pivene on the crest of a rock 1800 feet high above the Isthmus of Corinth. . ;.In his "Pegasus in Pound" Longfellow gives a similar story. "On tlio morrow, when tho village Woke to all its toll and Ciiro, Lo, tho strango steed bad departed And they linew not when or where. But they found upon tho green sward, Where his struggling hoofs had trod. Pure and bright, a fountain flowing :Prom the hoof marks in the sod. But why is Pegasus represented by little more than half a horse? The reason may be the dame as.in the-caso of some other constellations, that it was employed for the.figurehead of a ship. . Although a largo constellation, Pegasus is not rich- in objects for the telescope. It is quite outside the Milky, "Way, and-so is without the rich background enjoyed by the galactic constellations. But if we inclifde Alpha Andvoincda as Delta Pegaai there are no less than seven stars with individual

names. Alpha is called Markab, an Arabic,word for saddle. Beta, has alternative 'names, Sheat or Menkib, tho upper part of tho arm; Gamma is Algenib tho wing. Delta Pegasi or Alpha Andromcdac is called Alpherata, the head Epsilou is known as Enif tlio nose, Zcta is Homam the lucky star of the hero, and Eta isMatar the fortunate one. These seven stars arc at widely different distances from us. They are given as 80, 204, 407,110, 1630, and 3200 light years respectively, omitting only Zeta. They include representatives of nearly all the principle types as shown by the spectroscope. B, A', G> X, and M are represented by Gamma, Alpha, Eta, Epsilon, and Beta respectively. The only typo missing amongst the brightest stars, namely, Il', is supplied by the fourth magnitude star lota. Tho stars, with the exception of Alpheratz, are receding from us with velocities of a few miles a second. They vary very widely in intrinsic brightness. Alpha Pegasi is one hundred <.ues as brilliant as our sun, but that is little beside Epsilon and Eta, which are of thirty-six thousand and ninety thousand sun-power. There are a number of double and multiple stars in the constellation. Pi 1 and Pi 2 form a pure wide pair. Eta, a third magnitude star with a tenth magnitude companion ninety seconds away, is a test object for 3-inch telescopes. The main star is a spectroscopic binary. Epsilon is a triple star, but it: can be seen only as a wide double in small telescopes, the companion of magnitude 8.5 being 140 seconds from the 2.4 magnitude star. ' Kappa is a fine binary, the components of magnitudes 4.8 and 10.8 being 11 seconds apart. But one of these is itself a spectroscopio binary. Other spectroseopic binaries are lota and Eta. The star number 78 is a close double, the components of magnitudes 4.9 and 8 being only 2 seconds apart. In number 1 thirty-six' seconds scp.iratcg tho fourth" magnitude star, from its eighth magnitude companion. Number 30 is a triple star, two-twelfth magnitude companions being within six and ten seconds,of the 5.2 magnitude star. Xi has a twelfth magnitude companion twelve seconds away. Amongst the stars noticeable for colour are Epsilon, Psi, and thoso numbered 2, 7, 19, 35, 36, 55, 57, 71, 77, and 78. Beta varies between the limits 2.2 and 2.7 in 41 days. The changes in brightness are said to bo irregular. IT is a short' period variable ranging from 9.3 to 9.9 in 9 hours. R and S are long period ones changing from 6.7 to 13 and from 7 to 13 in 380 and 318 days. Ml 5, in front of the Horse's mouth, is a globular cluster, six minutes in diameter consisting of thirteenth magnitude stars. Dr., Rob-

erts counted 900 stars in it. Fifty of these have been found to be variable. The cluster is 48,000 light years from us, but is approaching U3 at tho rate of sixty miles a second. The radiant point of tho Pegasid meteors which are seen on 28th June is on the horse's neck, about seven degrees from Alpha. ,