Page:The Solar System - Six Lectures - Lowell.djvu/20



proceed to show you; for it is proper that we should recognize the members of the system before considering the system's constitution and the several characters of its constituents.

In many text-books you shall find it still stated that these flaming portents, the cometæ or long-haired stars,—for the ancients saw tresses where we prosaically see tails,—one of which, on the average, startles a generation into wonder, are visitors to us from other stars. So also we were taught that the strange stones that fall to us from the sky, and we call meteorites, were bits of some body from far interstellar space. Such knowledge belongs now to the history of science, not to science itself; for these bodies carry with them their badge of membership: it shows in the orbits they describe. So, when we pass through a comet's tail, or pick up a piece of meteoric iron, we now recognize that we have to do, not with a stranger, but with our own kith and kin. Man may gaze at matter beyond the solar system, but man has never yet touched it.

Proof of community lies in the character of the paths. Planet and particle alike turn out to travel in ellipses, and ellipticity betrays association. How the orbit labels the occupant we shall see, on finding the paths the planets pursue and why