Raun Thorp, age 11, of Newport Beach, California, for her question:

Why does the North Star stay in the same place?

Actually none of the stars march around our little planet every day. Some of them seem to do this because every calendar day the earth rotates once around its axis. As it turns, it spins us around to face a circle of heavenly scenery. The stars and the sun, the moon and the other planets rise and set because we are turning around with the earth. But this rotation does not change our view of Polaris, the North Star.

The earth, of course, rotates on its axis. This line through the middle of the solid planet runs from the North Pole to the South Pole. The big ball rotates faster at the equator, halfway between the poles. The rotation speed slows as we get farther from the equator and dwindles to nothing at the poles. It so happens that the North Pole points almost directly to Polaris. And since this spot on the earth's surface does not rotate, Polaris remains in a fixed position above the North Pole. At the North Pole, it is directly overhead. Farther south, it appears lower in the sky.