The Book of Stars: Being a Simple Explanation of the Stars and Their Uses to Boy Life

by A. Frederick Collins

In the last chapter we said that all the stars in the sky, including our Sun, are fixed in their positions; by this we mean that if we were to look at the Big Dipper every night for a hundred years we could see no change in the positions of any of the stars forming this constellation.

But if we look at the sky along the line of the ecliptic—that is the path of the Sun—one night after another we are likely to see a bright point of light which looks exactly like a star and yet it is certain that this point of light really does move among the other stars. What kind of a heavenly object then is this?

The bright point of light which thus seems to us to be a star when we look at it with the naked eye is really another world, or planet as it is called, and very like our own Earth. To prove that this moving point of light is really a world, or planet, and not a distant star, all you need to do is to look at it through a pair of opera glasses, or a small telescope, when it will be seen to be a round body, whereas a star when viewed through the greatest telescope is never larger than a mere point of light. ([See Fig. 50].)

Fig. 50.—A Star and a Planet in a Telescope.

The reason the planets, some of which are smaller and some larger than our Earth, can be seen to move is because they are quite near our Earth; that is, they are near when compared with the fixed stars.

Again, the reason the planets shine like the stars is not because they are hot and flaming bodies like our Sun and the other stars, but because the light from the Sun which strikes them is reflected to the Earth in exactly the same way that the sunlight falling on a mirror is reflected away in another direction.

Names and Sizes of the Planets.—The names of all the planets, and there are eight chief ones, should be learned as well as the order in which they are arranged around the Sun. The names of the planets are given below in the order of their size.

Mercury—The smallest planet and the one nearest the Sun. Pale ash in color. Has no moon.

Mars—The Red Planet. Reddish in color. Has two moons.