THE HEAVENS IN OCTOBER

Marlborough Express, Volume LX, Issue 232, 1 October 1926, Page 6

THE HEAVENS IN OCTOBER

(By

th© Director,

W anganui

Ubservatory.) PLANETS AND CONSTELLATIONS (By the Director, Wanganui Observatory.) The SUN is moving througli the eonstellation Virgo dnring the best j>art of October, passing into Libra at the ond of the month. Having {passed the equator into th© Southern Hemisphere, last month, liis movement is day by day further south, increasing his declination and altiftude by 11 d.eg. dnring the month. Solar activity was weli in evidence during September. A fine group of spots passed across the disc, being near the solar moridian on th© 18th and 19th. A measure of its total (length on the 20tli gave 172,000 miles. The MOON, in lier movement night by night towards the east, ipasses the planets and some of the brighter stars and serves as a convenient pointer to them. Sh© will be nearest Venus on the morning of the 6th, Mercury on the morning of the 8th, Saturn 'on the evening of the iOth, Jupiter on tho niglit of the 16th, Mars on the night of the 22nd. MERCURY is an evening star, | near the sun, at the beginning of Ithe month. He is drawing away from the sun towards the east, during tlie whole of October, and may be seen in the western sky at sunset, south of the sun, about the micldle of the month, and Jater he will be in lunar oonjunction on tlie 8th, in Aphelion on the 15th, being brighter at this time, being nearest the sun. VENUS is a morning star during tlie month. She is close to tlie sun and unfavorably placed for observation during the month. She will. be in lunar oonjunction on the morning of the 6th, and in greatest heliocentric latitud© north on the 8th.

MAPS is an evening star rising about 9 p.m. at the middle of the month, close to the Hyades Group in Taurus. He is now an interesting object in the telescope mlthough still far from bemg at his nearest, for this oppcsition takes place 011 November 4th. He will ■ be rather more tlian 47 millions of miles from the earth on the 15th of the month. JUPITER is now the most prominent phinef, and brighter tlian anv, but the moon, at this time. His soutliern declination. at this time, makes for exceptionally good telescopic seeing, at this time, and much fine detail can be seen on his "belts" in a good astronomical telescope. He becomes stationary amongst the stars on the , 14th, and will be in lunar conjunction on the night of the 16th. The best evenings to observe the transits, occultations. and eclipse® of his bi'ighter satellites will be those of the 1st,. 4th, 8th, 10th, 15th, 17tli, 18th, 19th, 23rd, 25th, 27th, 29th. SATURN is an evening star during the month but getting near the place of the sun, and must be obse'rved early in tlie evening. He may be seen in the west under the Scorpion, and over the star Alpha and Beta of Libra. He will be in lunar eonjunction on tlie evening of the 10th, Saturn being about five dianieters of Ihe moon distant towards the south. PLACES OF THE CONSTELLATIONS. The Constellations, as given below, will be found suitable for 10 p.m. of the istp 9 p.m. of the 15th, and for 8 p.m. of the 30th • of the month. Looking towards the north we see the Winged Horse, Pegasus slightly east of the meridian, witli the leading stars of Andronieda reacliing down to the north eastern horizon. Cygnus is well over towards tlie norwest with Dolphim over thi.s again. The northern Triangle and Aries are now seen with Cetus, from nor-east to east. Rather south of east the Stream of EridanUs rises up in great loops of stars to Achernar which is high up over the sou-east. The bright star Canopus is now beginning to rise on tlie eastern side of the southern meridian, followed by the other bright stars of Argo. Over those again are the two clouds of Megallans with Hydrus and Tbncan. The Cross is now low down in the south west, with the Pointers above, and the rest of the Centaur, and Lupus, over this ipoint The southern Triangle, and Pavo, with Ara, are over the Cross, and near the zenith is G.rus, the Southern Crane. Libra has about set, and the Scorpion is getting near tlie western horizon, with Sagittarius, Capricornus, and Aquarius along ihe line of th© ecliptic in the order given. Aquilai is high over tlie nor-west and near its setting at same point is the last of Lyra. TIME. Most people, nowadays, carry a watch, more or les§ reliable, and probably think very little aboutr time, and liow it is derived. A rather good storv was told some years ago, by astronomers, wlio went abroad to a'bserve fin eclipse of the sun. Arriving at some out of the way old seaport they were rather agreeably surprised at about midday to hear the report of a gun. They were informsd that this gun was fired each day at noon. Noting a certain inaccuracy they investigated. Arriving at a rocky platform above the town, they met the man in charge of the gun and, on inquiry as to how he ihecked his time, ivere informed that lie had a good nautical chronometer which was "looked after" by tlie svatchmaker, down in the port. Further inquiry elicited the information that when the chronometer, went to th© watchqiaker for cleaning he — the svatchmaker— lent tlie signal man his ! watch. The asti'onomers were as-i sured it was a very good watch. ! When they met this watchmaker it came out that he kept liiis watch by I the gun. and when ' he had tho j chronometer down to clean he kept ' that also by the gun. The astrono- ' mers, considerably interested, so we

are tohi, said nothing — at tlie time — but went on their way. Tho ancient Egyptians did bctter tlian this when tliey erected upright staves, or gnomons, and knowing north and south at least got true solar time day by day at noon. The next stap was to incline tlie gnomon i so that it pointed to the pole of the heavens. This was introduced into Greece, from Chaklea, in the form of sundials. Water docks (elepsydrae) were in use at Alexandria about 259 B.C. sand glasses came at a later date and remained in use until quite r-eoent times. For astronomical uses, and for navigation exact time is essential. The accuracy of the chronometer as turned out by some noted makers, is very great. Tlie docks of Dent of London, and Riefler of Berlin, are very fine. Oue of the latter was described, sometime back, by its owner, Professor Howe of Case School of Applied Science, at Clevorland, U.S.A. This clock was housed in a compa rtment having double brick wails, with arrangements for lcoeping the air betueen, and in the clock chamber, dry, and at constant temperature. The Vdock was wound autoniatically every five minutes, and rested on a massive pillar and in an airtight chamber of glass. Its finest reoord showed a variation of oue iifteen tliousandth of a second in a period of threo months; its greatest variation being the twenty two tliousandth of a second in a day. At this rate it vould not- lose a whole second in an ordinary lifetime. But this is negleoting the important elenient wear. The most uniform thing we know is the rotation of the Earth on its axis. It is eonsidered not to vary the one tliousandth of a second in as many years. All our time is reckoned from this, so that here we have the prime timekeeper. It is found by a tqlescope mounted very solidlv on two pillars by trunnion bearings in which it moves in a great circle cutting tlie equator at right angles. Setting this to tlie position of a star, in altitude, the rotation of the earth will oause the telesoope to pass over the istar, or as it will seem, the star will enter the field of view and pass across it. The

time it passes ihe centre is called a "transit," the greatest care being taken to secure tliis very exactly, by its passage over spider threads stretched across the field of view. The interval between two snch transits is knovrn as a sidereal day. This is shorter than the day we keep of 24 hours, on our docks, by nearly four minutes. The ordinary , clock time is known as "mean" time and is obtained by breaking. up the 365 davs of the vear into even periods of 24 hours. minutes, anl seeonds. This is a fiction so far as our relation with tlie celeistial bodies are concerned, but it suits because we must have some thing uniform. The time for all paris of the British Empire. and most others, is reckoned from that line which passes through tbe centre ofythe transit telescope at Greenwicli. Places east of this, to the 180th meridian are fast, or before, and places west after Greenwich, to Plie extent of four minutes for every degree. New Zealand timo is taken from the 172^ meridian, whicli is 11| hours in advance of Greenwich. Tliis again is a fiction for any place but that line which marks the 172f meridian through the islands of* this Domiiiion, but it serves quitfe well unliess wish to know when some celestial body will cross our meridian, when we soon find there is something wrong with the clock. But that is another, and a much larger subject.