Page:The evolution of worlds - Lowell.djvu/130

100 central mass would exercise a prohibitive action upon any planet trying to form within. In certain places it would not allow it to collect at all. The evolution of the solar family would resemble that of some human ones in which each child brings up the next in turn. So that the planetary system made itself, as regards position, a steadily accumulative set of prohibitions combining to leave only certain places tenantable.

In this manner we may perhaps be brought back to Bode's law as representing within a certain degree of approximation a true mechanical result, although no such exact relation as the law demands exists. That a relation seemingly close to it is necessitated by the several successive inhibitions of each planet upon the next to form, is quite possible.

One other general trait about their orbits is worth animadversion. In spite of being eccentric and inclined, they are all traversed in the same sense. Every one of the asteroids travels direct like the larger planets. In this they differ from cometary paths, which are as often retrograde as direct. Thus in more ways than one they hold a mid-course in regularity between the steady, even character of the planets proper and what was for long deemed the erratic behavior of the cometary class of cosmic bodies. Very telling this fact will be found with regard to the genesis of the solar family, as we shall see later.