When, where, and how, if ever, did this journey begin--when,
where, and how, if ever, will it end? This is the greatest of the
unsolved problems of astronomy. An astronomer who should watch the
heavens for ten thousand years might gather some faint suggestion
of an answer, or he might not. All we can do is to seek for some
hints by study and comparison with other stars.

The stars are suns. To put it in another way, the sun is one of
the stars, and rather a small one at that. If the sun is moving in
the way I have described, may not the stars also be in motion,
each on a journey of its own through the wilderness of space? To
this question astronomy gives an affirmative answer. Most of the
stars nearest to us are found to be in motion, some faster than
the sun, some more slowly, and the same is doubtless true of all;
only the century of accurate observations at our disposal does not
show the motion of the distant ones. A given motion seems slower
the more distant the moving body; we have to watch a steamship on
the horizon some little time to see that she moves at all. Thus it
is that the unsolved problem of the motion of our sun is only one
branch of a yet more stupendous one: What mean the motions of the
stars--how did they begin, and how, if ever, will they end? So far
as we can yet see, each star is going straight ahead on its own
journey, without regard to its neighbors, if other stars can be so
called. Is each describing some vast orbit which, though looking
like a straight line during the short period of our observation,
will really be seen to curve after ten thousand or a hundred
thousand years, or will it go straight on forever? If the laws of
motion are true for all space and all time, as we are forced to
believe, then each moving star will go on in an unbending line