elocity of one hundred and eighty
thousand miles a second? Only a very small fraction of it can be
received by the planets or by other stars, because these are mere
points compared with their distance from us. Taking the teaching of our
science just as it stands, we should say that all this heat continues
to move on through infinite space forever. In a few thousand years it
reaches the probable confines of our great universe. But we know of no
reason why it should stop here. During the hundreds of millions of
years since all our stars began to shine, has the first ray of light
and heat kept on through space at the rate of one hundred and eighty
thousand miles a second, and will it continue to go on for ages to
come? If so, think of its distance now, and think of its still going
on, to be forever wasted! Rather say that the problem, What becomes of
it? is as yet unsolved.

Thus far I have described the greatest of problems; those which we may
suppose to concern the inhabitants of millions of worlds revolving
round the stars as much as they concern us. Let us now come down from
the starry heights to this little colony where we live, the solar
system. Here we have the great advantage of being better able to see
what is going on, owing to the comparative nearness of the planets.
When we learn that these bodies are like our earth in form, size, and
motions, the first question we ask is, Could we fly from planet to
planet and light on the surface of each, what sort of scenery would
meet our eyes? Mountain, forest, and field, a dreary waste, or a
seething caldron larger than our earth? If solid land there is, would
we find on it the homes of intelligent beings, the lairs of wild
beasts, or no living thing at all? Could we breathe the air, would we
choke for breath or be poisoned by the fumes of some noxious gas?

To most of these questions science cannot as yet give a positive
answer, except in the case of the moon. Our satellite is so near us
that we can see it has no atmosphere and no water, and therefore cannot
be the abode of life like ours. The contrast of its eternal deadness
with the active life around us is great indeed. Here we have weather of
so many kinds that we never tire of talking about it. But on the moon
there is no weather at all. On our globe so many things are constantly
happening that our thousands of daily journals cannot begin to record
them. But on the dreary, rocky wastes of the moon nothing ever happ