ASTRONOMICAL NOTES FOR DECEMBER.

Press, Volume XLIX, Issue 14836, 29 November 1913, Page 10

ASTRONOMICAL NOTES FOR DECEMBER.

(Bt nn Ret. P. W. Faibcxough, F.R.A.S.)

The rate of the increase in the length of the day is now small, and little change will be noticed for the next s!x weeks, when a decline will be observed. At this r>eriod of the year, as we approach perihelion, our rate of motion m our orbit increases. This has one of those small effects on the day that

: -~ /V-sSB ■ ■ • ■'• prevents the sun from being a aooiisi timekeeper. The ■■ earthY \orbj&||| motion causes tho apparent journey of the sun/which causes constellation and the planets to westward across tho sky. If tho «iw marching eastward ho is marching wards sunrise, and meets tho earth a little earlier every morning.'.jfsfjjlt he marched at a constant pace it.wouJdi'ssf not matter to the timekeeper, but-aj#f he iocs faster at one part of the than at another, and is constantly creasing or decreasing his pace, he canfcsl| not bo that perfect timekeeper h©credited with being. ■ Mercury and Venus are stars, and will be in conjunction. o&tJS tho 2nd, Venus threo diameters of' moon to the north. On the 14th moon will bo in conjunction wjtS-;|| Saturn, and with Mars on the 16th, a«(Q| with Jupiter on tho 29th. fit? Saturn is in Taurus and Mart Gemini, near Kappa. Mars is still distant for small telescopes, but Satura'l| is at his best, for ho norths tow*fd*y§ midnight, and his rings aro well opea«L«?§ Tho eastward march of the 6un'wiß.||? soon deprive us of Jupiter, who rapidly sinking westward. : "%sf; Tho decease of isir Robert Ball triQiS be mourned by all readers of i»nular|g astronomy, for since the famous Proctor thero has beeu no one to ap*fg preach Sir Robert in translating struso mathematical conceptions iato%i| tho blocks and counters with, which\ofe| dinary mortals think. Tho real of the astronomer is simply the fixinsf-i of positions and the measuring of migiit; nitudes or distances. Tho great ma»|l of knowledgo and speculation about {lj*|| condition of heavenly bodies is inference from the observed facts, andlf! it is no necessary part of the astroiioijS; mer's work to draw these- inferaae«|| Yet those who condescend to do it,*awtl| do it well, not only educate but greatly benefit their science kindling the enthusiasm of future , servers, and by securing from the *%«§| ent tho gifts and endowments ■ thidp make new departures possible.'. Bif|| Robert Ball has no doubt done a greefe| deal in this direction. '■■'■<<*m A email comot of groat interests! now visible in tho Northern. Hemißphwi, J l It has been identified as and was last seen, in 1352. It is'Vb§| of six comets known to belong td.Nijjfcg tune's family, that is ; they were plw|| ably captured by him. Weetphal'ii'Jijp! by far the shortest in period, as "it.n|| turns after 61 years, its aphelion tance being almost exactly the same.a*| the mean distance of Neptune. HaHer%| comet recedes 300 millions of mil«»| beyond Keptune, and hence takes :, ym much longer time for tho round trjjjpj WestphaTs is the fourth comet of tl#| group that'has been observed-on ■tfi|| approaches to tihe eun. The oth«w| are those of Halley, Olbers, and The two that have not yet completed *| voyage since their discovery are.du»jf in. 1921 and 1927. They were .3il6| seen in 1846 and 1847.. . The "preseßs| visitor passed its perihelion about ;»| week., ago.. .- . .-, . ■ A J; || The investigations of Brun, waoinas| devoted many years 'to the enbjeoijf point to the coal mine order of" «s|S plosion as being an important: factor* in volcanic eruptions. Steam 1 u.proV| ably tie chief agent, bat be foundj|6af| many violent explosions were lowed by clouds of Trapuor as a etwni?| explosion would be.' Sometimes i|«| air remained quite clear, and there ! jjiß.g no deposit of moisture oa cold , eurfco«||i At other -.times,' -when .■ there■ / ■ *%Mj| cloud, instruments ? ehowedxltWJ nMjfyfji ture in it than oat of it. : 4n analye«| of secluded gases in; new lay*, ahowedj a large variety, including muoh bonic acid gas. Fumeroles show from| 62 to 77 per cent, of but thee©;| are expiring volcanoes, and it do*S|no*| follow -that 'there is a similar prepor-j| tion of hydrous* gas in tihe chimney■;«| a live volcano. . '■ ".■." ; ." ■..';:';..;■■ :''•■,/£■, The "figuring" or the ehaping; ;oxm the polishing of the 100-inch mirror Mt. Wilson is going; on, md Tnay\ta*tt| a year or two. The 60-inch took manjf| months.- WaxKJoated ieole , finest jeweller's rouge were it is said that iha mirror tf.;= not more -ffian one partin two*m?*| Kons out of absolute polishing tool has to rtst? erery «*i minutes to allow the glass to-eool^«A f Tery thin coat of is plaoed ort the rejecting surface^wth^^ie 11 does not enter the. glassyat ; all.; a^?;: are unable to use any **W%*!%®", to protect iie.saver.wd it ha* : . fore to be reeilvered two ,»*« \,

that about explosive of a rocket, ciently powerful to one ton weight at a *^\*Jj:"s*ss eecond, and traction of the earth and vmt %.» in 49 honre. He thinks that.-tyjeSgk soon make this world too genius of man, and that our;«M«««*S*& wUI be taking nights afieU. however, initial difficulties., present rate it will take many to collect the radium, and lected no one could go near it, and -$m sides it would be difficult to surrender ite energy in 40 stead of in millenniume. There;.-.wp other difficulties of a more aßtronomii!«| kind. In the first place, if the ehfJfe were once started at seven miles per : fm cond, it would not require.; the opag| tinuous kick of exploding carry it away from the earth. ■•'•'™|j initial momentum would be But escape from the attraction -of tM| sun is a different matter; no leee;th«f| 26 miles per second would be for that. A shell started from [W£ earth at seven miles a second ™>*JJ* slowly curve into an elliptical M»s round the sun, passing each revolutWp through the starting point. In all Wfe the propelling power this radium shell *j= Jules Verne's ingenious romance again. It is not so accurate, Verne would have remembered _ yam, radium gives off its corpuscles in directions, and that the resultantenergy could not be converted into./;; motion in one direction, seeing the co*"g puacles, unlike powder, pass thwaggs: the walls of the gun. '•'«** That sun spots are magnetic ™**A was suspected long ago, and proved »:;; few years back. The matter faw nog? advanced another stage, and it w_J»Vs lieved that the sun as a whole »•■*£ magnetic field, though not of the sity of the spots. The great instrutnes«N at Mt. Wilson seem to have the matter. The 75 feet graph and polarising apparatus tached to the 130 feet tower telescopy show displacements and duplication*! that can be explained only by istence of a general solar magnetic Tho fact that tho rays of the coro»*p aro bent back towards the Poles, but ; re|| main eroct ia other regions,- is qT"_«| in harmony with the idea. It ee«B||

probable that this will be an important rfL towards solring the solar problems. jt is thoaght that all rotating bodies jß*? bo magnetic fields. Professor fyfrosbex thinks that every molecule is •■■■■-. » ©agnet, because of the ewift revolution of the electrons of which it is compgsed. When such electrons aggregate V tjbeytend to lay their axes parallel to one another. Thus the early and all V its molecules have their poles lying in :. approximately parallel lines, and the • Biftgnetic pole almost coincides with tho ceograph'^ l pole. f or October, has "aa rtjde Proctor on the solar obrttory f or jfew Zealand, with two f ieff» of Nelson and its hills and a full -age portrait of Mr Cawthron. jir R- T - A - Inncs writing on Cosmogonies, remarks that there are four ■ invariable stages in the cycle of thkj batterfly's existence; the egg, the : t<r p;Uar, tho chrysalis, and the butterfly- We know it; uut Wa0 > jpotring only one stage, such as the could forecast tho others? But •■■ vien it comes to a trifle like the uni- /| ffaßf m en wax confidont, and describe ■ tbe infinite past and predict the changes of future aeons of time! All the samo ilr Innes goes on to expound another theory of the origin of the universe. It » compounded of Moulton and Chamberlain's Planetisimal theory and cf Axrhenius'e radiation theory. The primordial stuff was meteorites, he says. An original nebula, fire mist, or gas could not condense into solids. His argunionts aro ingenious, but too recondite for this column.

iur R. H. Tucker has been reconeidering the question of how many etars are within the ken of man and his instruments. Of course all statements on this subject are merely estimates. Xo one sets out to count scores of millions with hie eye glued to a telescope. It may be that in the future when the whole"fiky has been photographed with long exposures, that some enthusiast will devote his life to a steady, itreight out count of the images on the plates, but at present we have only rode estimates and averages. These estimates havo soared as high as 1000 mißionßybut * ne usna l estimate is 100 rniUiqm. Tucker concludes that there are. not inoro than 40 millions to tho lTifcfnfcgnitude—which may bo taken as jUie. limit of visibility, though they talk of the 100 inch reflector showing tie 21st magnitude. Up to a certain •' point the number of stars in each successivo magnitude increases enormously. Tiros, there are 14 of the Ist, 48 of the'2nd, 153 of the 3rd, 813 of tho 4th, 854 of the sth, and 2010 of the 6th. At the 10th we reach 843,000, which is based on a "system," and not on counting. According to the "system," stars should on the average be CTfcnly strewn through space, and therefore increase in number ac the space increases in volume. Failing brightness is attributed to increase of distance only, and the sphere of space bounded by any magnitude should be , roughly, speaking, four times the volume of that bounded by the next brighter " magnitude. Hence each, of the fainter magnitudes should be about four times as numerous ac the one above it. But it is certain that "the facts do not bear ' out this method of estimating. Up to the 12th magnitude the rule probably holds, but after that the rate of increase is-far from maintained; If it were maintained to the 17th magnitude the number would be about 16,000 millions, or nearly 400,000 to the square degree. Tucker's careful estimate gives aa average of 1000 per square degree. -The explanation of 'the great gulf be- • tv«a theory and,fact is that there is eifSer an extinction of light in space, ot tho stars actually do thin, out beyond a certain distance, indicating an v approach to the frontier* of our universe. .■ . •"■•'• :■■; ' ' ;■

,iA few yeare ago it was usual to refer ; epiral nebulae as incipient eolar ejetems; but that has now ceased to bo J.;*>jational,..' conclusion. Photography shows that spirals are very numerous, that in fact all the white nebula* are spirala;- Then comee th* spectroscope &nd proves that these spirals are not gaseous bodies, for they have a. solar spectrum and must, therefore, be distant masses of stars. The great spiral in Andromeda has at least 14 solar

linos, and there can be no mistake about it. The embryonic sun idea ie farther disproved by the prodigious size of the spirals.' That in Andromeda has a diameter four times that of the eun. Now if it ie only as distant as the nearer stars it would still have a real diameter, of 35 million million miles, which light would require seven years to traverse. If one side of it touched the nearest star, Alpha Centauri, the sjln would still be almost, m the middle of the vast spiral. It is, therefore absurd to talk of such a body being an incipient solar system. But. we have been supposing the very least imaginable distance for the ne<bula. If it should be placed among the further stars it would be fiOO times c* far away and have 800 times the diameter. Even that is far from the uttermost possibility. It may be scores of times as far away as the farther stare of our galaxy and constitute an exterior and independent galaxy ac vast, or infinitely vaster tkan ours. , It all depends on the dis**Bce,*and for anything at present known that may be anything up to injsnity.,.; ' '■ : Brazil has adopted standard time, ■two, three, four, and five hours slow of Greenwich. Hind's nebula, discovered in 1845, is raspected of great variability. This

s«w, for the first time since 1867, it is easily visible in a 61 inch comet seeker.