ASTRONOMIC THEORY.

Waikato Times, Volume 97, Issue 15979, 6 May 1924, Page 8

ASTRONOMIC THEORY.

THE GENESIS OF PLANETS, “ The secretary of the Royal Society in a discourse at the Royal Institution recently, made another notable contribution lo astronomical theory, stales the British Science Guild Service, in the ''Manchester Guardian.” According to the well-known nebular hypothesis of Laplace, it was originally a very extended rarified gaseous mass —what we now call a nebula, though Laplace had no knowledge of the actual existence of nebulae —and that, as il contracted through gravitation, it throw off successive rings of matter from its edge which ultimately condensed into the planets. This theory has been under grave suspicion for some lime, and Dr Jeans gave what appear lo be conclusive reasons for finally rejecting il lie has previously shown that stars arc probably born in a manner very similar to that imagined by Laplace, but smaller bodies like the planets require quite a different explanation. A discussion of the various possibilities leads lo the conclusion that, so far as our present knowledge goes, there is only one method left for their origin, and that is the disturbance of the sun in its infancy by the close approach of another sun. The gravitation attraction of the visitor would draw matter out of the sun by tidal action, and this matter would finally condense into planets. Such nn event would be exceedingly rare in the history of the universe, owing lo the great distances separating the stars from one another, and this consideration, coupled with the fact that at least half of the stars appear to be double or multiple suns, makes it very probable that our solar system is almost a unique structure. Science Is tending lo the conviction that our earth may be the only inhabited body in space. Professor W. IT. Pickering lias been extending his study of the mode jn which the moon was separated from Die earth, and he believes tint when that monstrous birth took place 700 million years ago the earth was not liquid but solid, and had a period of rotation, a day. of three to four Pours. The moon tore itself away in the South Pacific; probably the northern point of New Zealand was the last point of contact. Then threequarters of the earth’s surface to a depth of .‘To miles was carried away in a trailing mass of ruin. New Zealand was just saved. Prom a region by the Straits of Gibraltar, diametrically opposite, another piece of 11m earth’s surface . stretching out into the At tan lie almost necessarily followed the rest, and a ring of debris surrounding Hm earth mid analogous 1. ibe rings of Saturn was Pius formed. The portion lemi from the Atlantic was possibly some 1000 mdos in diameter. ;