John Wenger, age 11, of Seattle, Wash., for his questions
Why doesn’t the moon rotate?
The old moan can fool you in this matter until you think it out and perhaps do a small experiment, We never see the other side of our golden satellite because the same side is always facing the earth. Certainly it does not seem to rotate on its axis. But the heavenly bodies are often misleading. Actually, the moon does rotate, just as the earth rotates on its axis. If it did not rotate, we would see all sides during the course of a lunar month.
The lunar month is 27 1/3 days. During this tune, the moon revolves once around its orbit and rotates once around on its axis. Its rotation is equal to its revolution. While this is going on, the earth rotates around its axis 23 1/3 times. The planet and its satellite swing around like a pair of hoedown dancers.
Here i s an experiment you can do which will prove that the moon rotates once while it revolves once around its orbit. Place a ball or other round object on a small table. The ball will play tie role of the earth and you will play the role of the moon. Stand a few', paces from the table and get set to make your orbit, which is a circle around the earth.
Stand facing the ball, for your face is the face of the ',moon which faces the earth. To stay this way, you will have to shuffle around your orbit sideways, like a crab. Notice the wall you are facing before you start. Now shuffle a quarter way around your orbit and notice that you are facing a different wall. Half way around you are facing the wall opposite from the one you faced first.
Three quarters of the way around you are facing still an other wall. When you complete your orbit you are back facing the wall you faced first. If you had stayed in one spot and faced the four walls one after another, it would be plain to see that you turned completely around. This is also what you did while you were revolving around your orbit. You turned once on your axis while you revolved once around your orbit. This is the only way by which the golden moon can keep the same side facing the earth.
As the earth spins on its axis, it faces the sun with first one side, then another. This is what onuses day and night to sweep around the earth once every 24 hours. The rotation of the moon causes the lunar day and night. The lunar day is almost two earth week's long. Ws can see only the part of the moon which is lit with golden sunlight. During a lunar months we see the lunar day and night creep once across our side of the moon. When we see the thin crescent moon, the far side is in full daylight. When we see the full moan, the far aide is in the darkness of lunar night.