Page:The Solar System - Six Lectures - Lowell.djvu/36



In our identification of the members of our system we have thus got steadily farther and farther away. We began with the planets. Then we attacked the less evident and more erratic bodies, and we found that the nearest of them, the meteorites, were after all fellow-members, and circled quite near us, their orbits being comparable with, and possibly not alien to, the short-period comets.

Next we found the shooting-stars, the meteor streams, to be sun-controlled but travelling farther yet out into space, and connected with comets known to be periodic. We have now to take another step outward to the comets non-periodic, among which the most conspicuous of those visitants are numbered.

Non-periodic we may call them pending investigation. For their orbits are so vast that we know but vaguely what their major axes are.

Some four hundred of these stars with tresses have been seen from the earliest times of which we have records to the present day. Not a year passes that several are not discovered, but conspicuous ones are not over-common. In the last forty years there has been but one of superlative mien, and that was twenty years ago. The present generation has no conception of what a comet worthy the name can be. One of my first recollections