172 ON THE OKIGIN OF THE PLANETAEY SYSTEM. 



whose plane is almost at right angles to the planes of 

 the larger planets. It must at the same time be 

 remarked that the coincidence, in the direction of these 

 planes, is on the whole greater, the longer are the 

 bodies and the larger the paths in question ; while in 

 the smaller bodies, and for the smaller paths, espe- 

 cially for the rotations of the planets about their own 

 axes, considerable divergences occur. Thus the planes 

 of all the planets, with the exception of Mercury and 

 of the small ones between Mars and Jupiter, differ at 

 most by three degrees from the path of the Earth. 

 The equatorial plane of the Sun deviates by only seven 

 and a half degrees, that of Jupiter only half as much. 

 The equatorial plane of the Earth deviates, it is true, 

 to the extent of twenty-three and a half degrees, and 

 that of Mars by twenty-eight and a half degrees, and 

 the separate paths of the small planet's satellites differ 

 still more. But in these paths they all move direct, 

 all in the same direction about the sun, and, as far as 

 can be ascertained, also about their own axes, like 

 the earth that is, from west to east. If they had 

 originated independently of each other, and had 

 come together, any direction of the planes for each 

 individual one would have been equally probable; a 

 reverse direction of the orbit would have been just as 

 probable as a direct one ; decidedly elliptical paths 

 would have been as probable as the almost circular 



