MIRACLES OF SCIENCE 



ed this capture theory, in particular with reference 

 to the asteroids, which he thinks were drawn into 

 their orbits by Jupiter. Our moon also he regards as 

 a capture product. Its curiously marked face, he 

 thinks, shows the effect of the impact of asteroids as 

 it came through their zone. Each lunar crater, in 

 his view, marks the tomb of a planetoid, and not the 

 location of a former volcano. 



The planetoids themselves, by the way, were always 

 stumbling blocks to the Laplacian hypothesis. In the 

 new view they are simply largish planetesimals that 

 did not chance to lie near a larger nucleus of conden- 

 sation and hence have remained isolated, like myriads 

 of the yet smaller fragments we call meteorites. 



In a word, then, the planetesimal theory seems to 

 have a high degree of probability. It is easily the 

 most plausible hypothesis of the origin of the solar 

 system that has ever been advanced. It is peculiarly 

 hospitable to various interpretations as to details of 

 progression in world-making. No known fact of as- 

 tronomy or mechanics contradicts it vitally; a multi- 

 tude of facts support it. 



Of course it is not utterly nugatory of all that went 

 before. We have seen that the new theory, like the 

 old, conceives the solar system to have originated 

 from a nebula, it is still a "nebular" hypothesis. But 

 the entire change of view that it contemplates in re- 

 gard both to the original state of the nebula and the 

 stages of evolution through which a planetary system 

 is evolved, is so radical that the theory is fully entitled 

 to be regarded not only as novel but in a sense as 

 revolutionary. It extends to the planetary system in 



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