ASTRONOMICAL NOTES.

Press, Volume LII, Issue 15500, 29 January 1916, Page 7

ASTRONOMICAL NOTES.

FOR FEBRUARY.

(Br the Rev. P. W. Fairclocgh F.R.A.S.)

Venus is now conspicuous in the west soon after sunset. Jupiter will be found high in the north-west. Saturn is in Gemini, several degrees above tho two leading stars of that constellation and to the westward of tliem. Mars is in Leo. Though all these planets are not visible at one time, Venus having set before Mars rises, the evening sky *is now excep-. tionally rich. The apparition of Mira was not the spectacular success that I hoped. In the first place it came off before the time-table date. Indeed, Mira was at her best at the time I wrote, but as the weather was cloudy I had not noted it.* She rose to the second magnitude and remained visible till the late moon drowned her ineffectual fire. I find from enquiries that reach me that a few people from time to time undertake to acquaint themselves with the face of the sky. For this purpose a celestial chart or globe is necessary. Those published on several occasions by the "Weekly Press" are quite good enough to start with, and wiil indicate the form of the constellations and give the names of the principal stars. We will ask the editor to re-publish the map of the circumpolar region and will t?y herewith to point out some of its very interesting features. None of the stars in it are visible bej'ond the 45tli degree of latitude in the northern hemisphere. In the centre of it is the south pole of the heavens. This is a point that is practically fixed and stationary in the sky, and neither- rises nor sets. In Canterbury, when we look due south the pole is about midway between the Zenith and the horizon. You easily find the Southern Cross, which in the evening is now in the south-west and almost on its beam ends. Draw a line in your mind's eye from the head of the- Cross through the foot and prolong it about four lengths of the Cross. The end of your line will then be near the Pole, which almost makes an equilateral triangle with the two Magellanic clouds—the side leading to the larger cloud being somewhat the longer. To know this point is of the greatest importance in understanding celestial motions, for everything seems to move round it; or round an axis that slopes from this Pole down through the earth to the North Pole. No star not further from the Pole than the horizon can ever set. It simply swings round the Pole like the Cross itself, which is sometimes almost overhead and sometimes near the southern horizon. Now for some objects of interest: Let us return to the Southern Cross. The sta r at the foot of it is a double. The "Pointers" are the bright pair just below the Cross in the evening. The brighter of them is Alpha Centauri. It is by far the nearest star known, being only about twenty billion miles away, a distance, that light can traverse in about four years. Alpha gives about three times as much light as the sun. He is a double star, one of the finest and easiest to separate in the sky. The pa-ir revolve round their centre of gravity in 81 years. They are now at thoir greatest distance apart. Now look at the other Pointer (Beta Centauri; and draw a line from it to the nearest star in the Cross. To the 'north of Beta you will sec another star, smaller than any of the four in the Cross. This star makes a shapes., equai-siued triangle wilu ijeca and the nearest star in the Cross. Now prolong ) the base of this triangle nearly its own length' from Beta through your new star. The line leads you to a misty star. That misty star is the famous Omega Centauri. the . finest globular cluster in the heavens. Even I oinocuiars will show you what it is; but great telescopes reveal more than j 10,00U stars in that one misty star! Now turn to the Magellanic Clouds: those two fragments of the Milky Way which neighbour the Pole. These are perhaps tho most mysterious objects in the sky, and it is not known whether they are part of our System or outside island . universes. They contain vast numbers of nebulae, of variable stars and the like. Now mark the smaller one, Hebecula Minor, and note just below it another misty star. That is "47 Tukani," and another amazing globular cluster. Try the binoculars on it. Only one astronomer signed the manifesto of Germcn men of science on the war. He must have been the "undevout astromoner," who, as the poet says, "is mad." Mr Denning, the shooting star specialist, describes the paths of two meteors recentlyi seen from two stations. The meteors were Aquarids; that is of tho Halley's comet family, and were therefore of special interest. The "radiants," or tno points, at which the meteors first appeared, were within four degrees of each other;-the speeds were 37 miles and 40 miles per second. The former sloped in its visible path from 48 miles high to 40; and the latter, which was bv far the larger, from 69 miles high to 60. The comet is now far on its outward voy-. age, between Saturn and in j. fact; and yet some meteors that were once presumably 'part of the nucleus are still straying in our neighbourhood 1. Tills indicates a high antiquity for the comet. It has been traced back for 2150 years in human records, but the wide scattering of. these fragments by the differential perturbations of the planets would require far more time than that. It will be quite natural to ask how these stray meteors are identified. The answer is that it is now a well-established fact that comets have troops of outriders in the form of meteors widely spread along and around their path; that the meteors in question came from tlie region of the sky through which the comet's path passes and had a direction corresponding to that of the comet, and, most important of all, that the rate of motion observed in the meteors was similar to that of a body falling towards the sun from beyond Neptune, the distance to which the comet retreats. One of the easiest ways for amateurs to serve astronomy is to observe meteors. Any two persans who knew the face of the sky, and who lived, say, ten miles apart, and who would both watch a region of the sky for certain hours and carefully record the path and time of every shooter seen, would in the course of a very few years compile a most valuable record.* ''Knowledge" contains a series of articles by Professor A. W. Bickerton, °n the "Graphics of Gravitation." which lead up to partial impact and the creation of the Third Bodv.