132 SIMPLER ORGANIC SUBSTANCES 



verse and that a star with comparatively small cold bodies 

 circling round it is the rule, rather than a rare exception 

 as was thought a few years ago. As a result of these studies 

 there was a withdrawal from the so-called ' catastrophic ' 

 theories of the formation of our planetary system which, 

 until recently, prevailed among cosmogonists. 



According to such theories, and in particular to that of 

 Sir J. H. Jeans^"® (which was the only theory of the formation 

 of planets current twenty years ago) the Earth and the other 

 planets of the solar system arose as the result of an excep- 

 tional event, a ' catastrophe ', namely the close approach of 

 another star to our own Sun. As the result of its gravita- 

 tional attraction, a stream of incandescent gas was drawn 

 off from the Sun and this provided the material from which 

 the planets were later formed. This theory came in for devas- 

 tating criticism at the hands of H. N. RusselP^° who showed 

 that the theory of the origin of the solar system by collision 

 between some other star and the Sun was incompatible with 

 the law of the conservation of momentum. 



In 1943 detailed calculations made by N. N. Pariiskii""^ 

 demonstrated completely the incorrectness of Jeans' theory 

 and later attempts to revive it in one form or another have 

 not been successful. Furthermore, all the physico-chemical 

 and geological data disagree with the hypothesis that the 

 Earth was formed from gases which were originally 

 incandescent. 



Judging by the statements of the cosmogonists, most of 

 the investigations in this field suggest that our planetary 

 system is not the result of some very rare, ' happy ' accident 

 or catastrophe but that it, like many other analogous systems, 

 arose as a completely normal phenomenon in the course of 

 the gradual development of matter. According to this hypo- 

 thesis the material from which the planets were formed was 

 not provided by incandescent gases but by relatively cold 

 substances scattered through interstellar space. 



Thus contemporary scientific ideas on the origin of the 

 planets return, in principle, to the hypothesis advanced by 

 I. Kant"^ more than 200 years ago. 



Kant considered that the material which now makes up 

 the planets did not always constitute a system of isolated 



