YOU all know that the sun comes to us in the morning, and goes away from
us at night, and you say that it rises and sets. Does it rise and set in
the same place?
I know that is a foolish question to ask any child who lives with his
eyes open. You all know, of course, that it rises opposite to where it
went down the night before, and takes all day to cross the sky to its
setting-place again. And you know it rises in the east, and sets in the
west.
But do you know that most of the stars, too, rise and set in this same
way? Those of you who are old enough to be up when the stars are out can
see for yourselves that this is so. You can see some stars rise, and
some set, if there is nothing in your way, and you patiently watch; or
you can pick out a particular star, and notice just where it is, and
then, if you look for it later, you will see that it appears to have
moved.
All night long, and all day too, only we cannot see them in the
sunlight, stars are rising, crossing the sky, and setting, the same
stars coming up a little earlier each day. But there are some stars
which neither rise nor set, and these I will tell you about some other
time.
Now, after all this that I have said about the rising and setting of the
sun and stars, you will be surprised to learn that, so far as we can
see, they never move at all. The planets--and our earth among them--move
around the sun; but the sun stands still; and all the stars which are
suns, shine always in the same place, and are hence called fixed stars.
How, then, can they be said to rise and set?
I will try to explain this in the next lesson. In the meantime you had
better read again what I told you about the planets in the second
lesson.