THE DIPPERS AND THE POLE STAR
I never heard of any boy or girl who didn't know the Big Dipper. But there is one very pleasant thing about the Dipper which children never seem to know. With the aid of these seven magnificent stars you can find all the other interesting stars and constellations. So true is this that a book has been written called "The Stars through a Dipper."
To illustrate, do you know the Pointers? I mean the two stars on the front side of the Dipper. They point almost directly toward the Pole star, or North star, the correct name of which is Polaris. Most children can see the Pole star at once because it is the only bright star in that part of the heavens.
But if you can't be sure you see the right one, a funny thing happens. Your friend will try to show you by pointing, but even if you look straight along his arm you can't always be sure. And then, if he tries to tell you how far one star is from another, he will try to show you by holding his arms apart. But that fails also. And so, we all soon learn the easiest and surest way to point out stars and measure distances.
The easiest way to tell any one how to find a star is to get three stars in a straight line, or else at right angles.
The surest way to tell any one how far one star is from another is by "degrees." You know what degrees are, because every circle is divided into 360 of them. And if you will think a moment, you will understand why we can see only half the sky at any one time, or 180 degrees, because the other half of the sky is on the other side of the earth. Therefore, if you draw a straight line from one horizon, clear up to the top of the sky and down to the opposite horizon, it is 180 degrees long. And, of course, it is only half that distance, or 90 degrees, from horizon to zenith. (Horizon is the point where earth and sky seem to meet, and zenith is the point straight over your head.)
Now ninety degrees is a mighty big distance in the sky. The Pole star is nothing like ninety degrees from the Dipper. It is only twenty-five degrees, or about five times the distance between the Pointers. And now comes the only thing I will ask you to remember. Look well at the two Pointers, because the distance between them, five degrees, is the most convenient "foot rule" for the sky that you will ever find. Most of the stars you will want to talk about are from two to five times that distance from some other star that you and your friends are sure of. Perhaps this is a little hard to understand. If so, read it over several times, or get some one to explain it to you, for when you grasp it, it will unlock almost as many pleasures as a key to the store you like the best.
Now, let's try our new-found ruler. Let us see if it will help us find the eighth star in the Dipper. That's a famous test of sharp eyes. I don't want to spoil your pleasure by telling you too soon where it is. Perhaps you would rather see how sharp your eyes are before reading any further. But if you can't find the eighth star, I will tell you where to look.
Look at the second star in the Dipper, counting from the end of the handle. That is a famous star called Mizar. Now look all around Mizar, and then, if you can't see a little one near it, try to measure off one degree. To do this, look at the Pointers and try to measure off about a fifth of the distance between them. Then look about one degree (or less) from Mizar, and I am sure you will see the little beauty—its name is Alcor, which means "the cavalier" or companion. The two are sometimes called "the horse and rider"; another name for Alcor is Saidak, which means "the test." I shall be very much disappointed if you cannot see Saidak, because it is not considered a hard test nowadays for sharp eyes.