GLORY OF THE STARS.

New Zealand Herald, Volume LXIV, Issue 19625, 2 May 1927, Page 12

GLORY OF THE STARS.

THE HEAVENS IN MAY. PLANETS AND CONSTELLATIONS. BX CItUX AUSTRALIS. fhe Sun is in the constellation Aries until May 14, when he enters Taurus. His apparent motion is toward the north, decreasing his altitude from 38 degrees on May 1 to 31 degrees on the 31st. The Moon will be in conjunction with Venus on the 4th, Mars on the 6th, Saturn, on the 18th and Jupiter on the 26th. Mercury is a morning star during May, but, as superior conjunction with the Sun occurs on May 20, he will at no part of the month bo favourably placed for observation. Venus is an evening star during the month, moving from Taurus into Gemini on the 12th. She is drawing away from the Sun and setting later every evening.' Mars is an evening star in Gemini throughout the month. He is distinguishable by his ruddy hue, but is now too far away from the Earth to render observation profitable. Jupiter is a morning star in Pisces and is increasing his elongation west of the Sun, so that he is rising earlier each morning. Transits, eclipses and occupations will be visible on the following mornings: 3, 4, 5, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 26, 27, 28, 29. Saturn is a brilliant object in Scorpio this month. He will be in opposition to the Sun on May 27. Comet Pons-Winnecke was detected on March 3 by Professor van Biesbroeck at the Yerkes Observatory, U.S.A. It was found quite near its predicted place, and it appears that it will pass nearest to the Sun on June 21. The Constellations. The constellations, as given below, may be seen as indicated at 10 p.m. of the Ist, 9 p.m. of the 15th and 8 p.m. of the 31st of the month. Canis Major is now setting in the south-west, while Canis Minor ia setting further to the west. Above Procyon is the faint' constellation of Cancer, containing the * beehive " cluster of stars, and above Sirius Is Argo, a large and brilliant group, whose brightest gem is Canopus. Following the Galaxy from Sirius through Argo, we come to the Southern Cross, shining prominently almost overhead. To the north and east of the Cross is Centaurus, with its two bright pointers. Still following the flow of the Milky Way we come, to the two small ' groups of Lupus and Ara, which lie between Centauru3 and Scorpio. The brightest star in this group is Antares, which, as its name implies, rivals the planet Mars in its ruddy hue. Below Scorpio, Sagittarius is rising in the south-east. From near Scorpio a stream of faint stars runs in a straggling line parallel to the Galaxy toward Cancer in the west. This is the con stellation of Hydra. The prominent constellation of Leo, with its bright star Regulus, is now near to setting in the north-west. Between Leo and the zenith are the small groups of Crater and Corvus, the latter consisting of a small quadrilateral of four fairly bright stars. Below Corvus on the meridian is the large group of Virgo, containing the bright star Spica. To the east of Virgo, Libra and Ophiuchus are rising, and in the north-east Bootes is now prominent. Its brightest star is Arcturus, possessing a distinctly orange colour. This splendid star is just on the verge of those whose distances can be measured; its light takes nearly a century to reach us, and at its distance our Sun would be visible only in a telescope. On the northern horizon are the small groups of Coma Berenices and Canes Venatici. The Planet Saturn. The most charming of celestial objects and the wonder planet of the solar system is Saturn, which is now shining with a soft golden lustre in our evening skies. It is difficult to conceive that within the limits of our own system there can exist a world so unlike our own. The planet, with its glorious ring system and lovely retinue of satellites, is a captivating sight in the smallest of telescopes. Saturn to the naked eye gives no hint of the grandeur of its system; it presents the appearance of a moderately bright star with a very slow movement in space. By reason of its tardy movement the ancient poets bestowed on it the name of the God of Time—an old man who slowly and inexorably pursues his endless path. At a distance of 886,000,000 miles from the Sun, Saturn completes its orbital journey in 29£ years. Large enough to contain 719 Earths, Saturn is so small in den sity that it is the only one of all the planets that would float if placed in a huge ocean of water.

Through the finest telescopes Saturn appears as a globe surrounded by clouds, and the details of its surface are therefore hidden from us. Wo know, however, that it possesses a very dense atmosphere, and that it revolves on its axis in about 10i hours. One result of this rapid spinning is that the clouds which cover the planet's surface are arranged in belts parallel to the equator in form so regular that one could imagine they had been turned in a lathe. The Wonderful Kings.

First seen in 1610, when Galileo turned his telescope to the study of Saturn, the rings of Saturn have since then been of universal interest. Around the planet an immense, thin, flat ring forms a girdle. This ring is encircled by a second and this again by a third. The inner, or "crape" ring, is faint and dusky, and through it the body of the planet is visible. A broad ring, the brightest of all, comes next, and this is separated from the bright outer ring by a vacant space about 2000 miles wide. The planet cannot be seen through the two outer rings, which, of the same colour as Saturn itself, cast a dark shadow upon it. By far the most astonishing feature of the rings is their relative thinness. They are probably not more than 100 miles thick, and when they are presented edgewise to the Earth, which happens twice during a revolution, or every 15 years, they are visible only as a thin line across the planet's disc. The rings were edgewise in 1921. and will be in that position again in 1936. They are at present opening out, and in 1929 the ring system will appear most open. The rings are not continuous, solid bodies—each is composed of dense swarms of minute satellites, perhaps no bigger than a few yards across, revolving independently in distinct orbit® with periods corresponding to their several distances from the planet, and varying from four to 13 hours in duration. The innumerable members of the rings are separated bv appreciable distances, as has been proved at such times as stairs have passed behind them—the stars being visihle through even the densest portions of the rings. Besides its rings, Saturn has a retinue of ten moons, a greater number than any other planet. Titan, the largest, is a little bigger than Mercury, and performs; a revolution round its primary in nearlv 16 days. The innermost is Mimas, which revolves in a period of 22 hours, while the most distant, Phoebe, takes 550 days to perform a single revolution. Saturn is assumed to be the youngest planet. n«t in years, but in development, but whether the rings of Saturn are a finished structure or represent a transitory stage in the development of the planet, is a question which has yet to be decided.