MIRACLES OF SCIENCE 



And even if the seventh satellite of Jupiter should 

 prove on further examination not to have a retrograde 

 movement (the question is not quite settled) there 

 would still remain such anomalies as the exceedingly 

 rapid rotation of the innermost moon of Mars; the 

 ever-puzzling fact that neither the sun itself nor any 

 of the planets revolves fast enough to produce a cen- 

 trifugal effect adequate to overcome the attraction of 

 gravitation; and the vital fact that the planets do not 

 revolve in the plane of the sun's equator. 



Moreover Professor Moulton in 1909 carried out 

 an elaborate mathematical investigation which seems 

 to render it at least doubtful (1) whether a revolving 

 gaseous body, such as the original Laplacian nebula 

 is supposed to have been, could develop the mechan- 

 ical conditions necessary to whirl off a ring of its sub- 

 stance, and (2) whether such a ring could assume the 

 form of a planet even if it were detached. 



THE PLANETESIMAL THEORY SOLVES MANY PUZZLES 



The planetesimal theory, on the other hand, seems 

 to afford a fairly satisfactory explanation of all the 

 observed anomalies of planetary revolution and rota- 

 tion, without doing violence to any recognized law of 

 mechanics. 



For example, the crucial facts that the sun rotates 

 slowly and that the planets do not revolve in the plane 

 of the sun's equator, present no difficulties, since 

 neither the direction nor the speed of the sun's rota- 

 tion is conceived as having had anything to do with 

 the genesis of the planetary system. The sun merely 

 continues to rotate like the big top that it is on the 



