Betsy Klaczak, age 12, of Pittsburgh, Pennsylvania, for her question:

Is it true that the sun never sets?

Every evening, of course, the sun sinks down in the western sky above Pittsburgh and sets below the horizon. Except for the polar regions, it sets each day above every place in the world. It is also quite true to say that the sun never sets at all. For while it is setting above Pittsburgh, a new sunrise is dawning in Tibet, on the opposite side of the globe. The globe itself explains the mystery. Our planet is continuously turning around and around on its axis, like a spinning top. As it rotates, it turns first one side then another to face a great blazing star which is about 93 million miles out there in space. This star, of course, is the sun that never sets.

The earth spins towards the east, and on its surface the city of Pittsburgh spins around with it. During the night you are turned away from the sun but the far side of the globe is turned to face it. In 24 hours the earth spins you clear around in a circle and through every calendar day the sun is shining on half the globe. As it sets on one side, it rises on the far side and never does it set on the whole world at the same time.