Page:The Solar System - Six Lectures - Lowell.djvu/151



conclusively by their several masses. Present mechanical conditions of the matter inside Jupiter's orbit appear to point to the pre-existent influence of Jupiter upon it before birth. Not only do the amounts of matter in the several terrestrial planets indicate this, but the lack of formation of a planet in the gap occupied by the asteroids seems well-nigh conclusive on the point.

A glance at the axial inclinations of the outer shown by and the inner planets betrays a break in the symmetry of their arrangement. Each, taken by itself, evinces a gradual righting of the axis as one approaches the Sun. This appears strikingly from the table of the inclinations of the equators of the several planets to the planes of their orbits.

This, too, seems to point to the action of Jupiter. On the whole it appears probable that Jupiter existed before any of the small planets within its orbit, and profoundly modified them prenatally.

We thus come to a conclusion in which nothing is concluded : but we need not regret that. The subject becomes the more exciting for remaining yet a mystery. We now know of relations so systematic and singular that we are sure some law underlies them, and it is rather pleasant than otherwise to have that law baffle our first attempts at discovery.