CONCERNING COMETS.

Waikato Times, Volume XIX, Issue 1617, 14 November 1882, Page 4

CONCERNING COMETS.

The history of comets is the history of a jemarkably slow development. The earliest story ou record is of the appearance of two comets at the birth of the great Mithridates, B.C. 133. They aie described by the historian as out shining the splendour of the mid-day sun, occupying the font th part of the heavens, and remaining for 72 days. No one out of the couutiy of Mithridates seems to I have seen those beautiful stiangeis, but I that, of course, need not lead ns to doubt | their existence. They wero a poi tout, for jUifchriclates. As he had a splendid career, and an ignominious end, the two comets weie justifies I either way. A trifle over a hundred years later people had not got to know much moic about comets, for they regarded the comet of 43 Ji.c. as the soul of Julius Cesar wandering about accusingly in the atmosphere. Prom which we learn nothing useful about comets, but a great deal about the mighty influence and great fame of Julius Cesar. Some 13 centimes passed without finding people learning any tiling more useful about comets. But knowledge was accumulating, as is proved by the growing terror inspired by the fiery monsters. This terror arrived at its climax when the tall of Constantinople was followed by a brilliant comet and an eclipse of the moon. " Lord deliver ns from the devil, the Turk, ami the comet,"' prayed universal Christendom. A hundred ycais later Tyelio Bra he found that the recorded observations of 1600 years had grown plenteous enough for a conclusion. The result was tint he expelled comets from the position they had been supposed by popular belief to occupy in our atmosphere. But the transition fiom the sublunary world to space obtained for comets a greater share of lespecttul tenor. They were discovered to be heaveniy bodies of great size travelling about in eccentric orbits at enormous velocities. The world ceased to be safefiom collision. When a comet appeared those who knew anything of astronomy — a very few, happily for the peace of mankind—prepared to die with calmness and dignity. About a ccntiuy this kind of thing continued, till Sir Isaac Newton discovered that the law of m avitation ruled comets m, it docs other heavenly bodies, and that they wove in leguUzi oibifo>. Immediately alter the comet wovhi Iv.ul been thus reduced to a level of oidcrlincss and regularity with its neighbours, Hallcy succeeded at the end of the seventeenth century in identifying many apparently different comets as in reality reappearances of the same comet, confirming the tbeoietic conclusions of Newton by grouping and comparison of a se\ en teen centuries range of facts. Then it was iound that the matter of comets is too nebulous to hurt anything it touches — all but the nucleus, th.it is to say. When the world was accustomed to this view, it was told that contact of oui atmosphere w itli cometicles w ould be beneficial. Thus reassuied the year 18(51 found mankind ; and provided a comet which came so near that "we weio in the tail," which was 400 miles in diameter, theic being in the atmosphere a " phosplunescent, auroral glaic." Thus the harmlcssnesi of comets has been definitely demonstatcd. The nucleus may of course stukc against anything, but theie is plenty of room in space for any number ot nuclei, and the rule of the road is regulated with ' lemaikable nicety and precision. Comets are said to shed a benign influence on vintage, and it is certain that in comet years veiy good wine — the best on record — has been made. Let us hope that the eflect if any, extends to all kinds ot hanests. The laigcst comet ever seen (bar those which appealed in the days of Mithiidatcs\ was Donati's comet of 1838, which was 40 millions of miles long, and 2SO millions of miles from the earth. The comet of IS6I, which co\cred the caith with its tail, was travelling along at the late of ten million miles jn the twenty four hoiu^, and the ■velocity of most of these \isitois is in no coses less, and sometimes more. The comet that ha.s as yet lcmamed with us the longest was the comet of 102!), which was visible in the heavans for live months. The orbits of these bodies aie all defined, and icgular, but their] regularity jb .sometimes ot so complex an Older as to appeal ineijulai. Ah foi instance, the comet of Meisicr in 1770. This body was declared by Leieil, the astiononiet, after long obsei sation, to be moving in an orbit implying a periodic l evolution of ~i\ year. Hut tho comet had ncs er been seen obsei\ed befoic and has ne\ei been ■h'cii since. The matter is thus explained by astionoinei.s. Before 1770 this comet'-* oibit was in distant legions, so that it was not seen, oi, if seen, not in same brilliancy, 01 pi eventing tho form as in 1770 ; and since 1770, its oi bit has again become distant. The distuibing taii'-e ■which biought it within % low in 1770, and has kept it out of s icsv since, is, the astronomeis) tell us, the planet .Jupitci. The influence of that huge bulk dcilected the comet into \ iew in 1770, and deflected it back again into its original mhit m the distant legions of space on meeting it on its letiun journey iound the sun. A eompaiisun ot the two oibits has left the matter beyond doubt. The Mm, we see, is the king and go\ernmg power of the comctmy system, as lie is of the plnnctaij'. The cometaiy oibits aic well defined and regular but the comet bulk being small the cometaiy oibits are apt to be disturbed by the planetaiy influences. As the sun tia"\cl.s thiough space — at what velocity we know not, in what oi bit, and iound what gieatev sun we aic equally ignOMnt—ho takes with him his attendant planetaiy and comctary satellies, each tiavclling m its orbit, and performing its l evolution round his great governing ccntie in its appointed time. Of this system is the bright luminary now \isible in the morning sky, which we have eironeously got into the habit of calling a .sli ingti. lv loahly, lie is one of ourselves, blithe tiavcis fuithur than any of our more regular acquaintances, and docs not \isit us very ficquently. We, therefore, greet him, as we do all friends who behaxe in the same manner, with " Quite a stranger." That is the only sense in which he i.s a sti anger. He is dei'tafcd by some to be an enemy, oi looked upon at beat as a .soit of serpent-in-tlie-bosom kind ot guest. By these, he is said to have made his appeal ance many times before, the inteival of absence m each rase getting shoiter. His oibit iound the sun is thus getting .smaller, and the icason is that the influence of the sun inwaids is pie\ ailing over the iniluence which acting outwards must be equal to maintain equilibrium of orbit It is plain then that having appeared in 1843, after an absence of 37, and being liei c now of mornings, after a wandering of two yeais only, lnscaieer is ncaily at an end. If the warlike Jupiter does not tear him awoy, or if he proves indifferent to the soft seductive charms of Veinns, his fate is only too plain. A plunge headlong into the vast eternities of the sun, and no more of Master Comet. Now it might be thought that this, concerning the poor comet alone, is leally nobody else's business. But that is where tho comet's critics come in w ith their theory. The)' say that by weakly yielding to the influence of the sun he endangers his friends as well as himself. This prodigal's descent into the Avei uian depths of the sun is likely to be bad for us in particular, we are told, because our planet alone is known to have life upon it. In this way : velocity has its equivalent m ' , heat : when the unhappy comet collides ' with the sun his enormous velocity will be converted into heat ; the result will be a considerable increase in the heat of the 'sun. In consequence there will be combustion of al| men and cities on this jyianet. Well ! let us grant that the comet is rushing to, destruction. ' When lie gets into ;the sun it will be found that l>i« nucleus 19 too small to effect the heat of that enormous bulk. As to thq tail, if the tail of the comet of 1861 did riot set • ihe 'earth on fire; wheft it b^phed into tho !

atmosphere, the equally luminous nnd nebulous tail of our poor doomi'd f i ioiul of to-iky will not do much 't»t .his death towards enabling the sun to perform that dreadful feat. Let us continue to watch him with feelings of pure admiration, and if w« believe that h<s is nwrif'irm let us salute him and breath a sigh of unmixed pity on er his sad fate— Lift iiVuu Time*.