ON COMETS.

Kumara Times, Issue 1049, 10 February 1880, Page 3

ON COMETS.

Comets differ in so many respects from planets, that, beyond the fa'cts of their belonging to the same system and obeying in their motions the same laws of gravitation, there is little analogy between- them. The word Comet is derived from the Greek kora6 , (hair), the hbbulohs ■■ matter composing the doriift and t&U’. hair, and the object being therefore called komdtes (a hairy star). The following extracts taay prove interesting at* the present time. Professor Mitcheljj in One of his' lectures on the “ Planetary and Stellar Worlds/' says “The wonderhil characteristics which mark - the* flight of comets through space-r-the which they blaze forth—their exceeding velocity and their terrific appearance—their eCcentiic motions, sweeping towards the sun from all,regions and in all directions—have rendered these bodies objects of terror and dread in all ages of the world. While the planets pursue an undeviatiug course round the sun in orbits nearly circular, and almost coincident with the plane of the etkrth’s Orbit, all revolving harmoniously in the same direction, the comets perfo«m their.revolutions in orbits of every possible eccentricity, confined to no particular plane, and moving indifferently in accordance with, or opposed td> the general motion 6f the planets, they come up from below tile plane of the ecliptic* or plunge downwards towards , the snh from . above—-sweep swiftly round this their great centre, Uhd, with incredible velocity, win" their flight far into the fathomlesss regions of space, in some basCs never again to reappear to human vision. In the early ages ' of the world, superstition regarded these wandering fiery Worlds with awe* and looked upon them as omens of pestilence and war ; and, indeed* even in modern times, no eye Can look upon the fiery train, spread out for millions of miles athwart the sky, and watch the eccentric motions these anomalous objects, without a feeling of dread. The movements of the planets inspire confidence. They ate Over visible, and true to their appointed times, while the comet* erratic in its course, bursts suddenly and unannounced upon the sight; and no Science can predict in the outset its Uncertain track. Whether it may plunge into the sun, or dash against One of the planetary systems, or even come into collision with our own earth* is equally uncertain, until after U.Tjjufficient number of observations shnl hate been made, to render tin computation of the elements of itt orbit possible.” Dr. Lardney, in his “Handbook of Astronomy,” mys :— “ In respect of magnitude the tails of comets are unquestionably the mosi

stupendous objects which the discoveries of the astronomer have ever presented to human contemplation. The following are the results of the observation and measurement of a few of the more remarkable {— Bate of (Greatest observed Length Appearance. of Tail. 1847 5,000,000 mile*, 1744 19,000,000 y, 1709 40,000,000 „ 1858... ... 45,000,000 „ 1618 50,000,000 „ 1680 100,000,000 „ 1811 100,000,000 „ 1861 130,000,000 „ 1843 200,000,000 „ The magnitude of these prodigious appendages is even less amazing than the brief period In which they sometimes emanate from the head. The tail of the comet of 1843, long enough to stretch from the sun to the planetoids [over 200,000,000 miles] was formed in less than twenty days. * * Notwithstanding the enormous number of comets, observed and unobserved, which constantly traverse the solar system in all conceivable directions; notwithstanding the permanent revolution of the periodic comets, whose presence and orbits have been ascertained ] notwithstanding the frequent visits of comets, which so thoroughly penetrate the system as almost to touch the surface of the sun at their perihelion, the motions of the various bodies of the system, great and small, planets major and minor, planetoids and satellites, go on precisely as if no such bodies as the comets approached their neighborhood. Not the smallest effects of the attraction of such visitors are discoverable.”