Mimi Horn, age 11, of Bartlesville, Oklahoma, for her question:

Who puts the light in a satellite?

There could, of course, be a giggly riddle type answer to this question. But since many readers wonder about the starry glow of an orbiting satellite, we can treat it as a serious inquiry. If there were a man made light within a satellite, chances are it would be far too dim to be seen from the ground. Nevertheless, as many of us have seen for ourselves, a satellite does glow. It may even outshine a star. Actually, the light does not come from inside the little traveler. It is merely the reflected glory of the sun. Reflected sunlight also shows us the faces of the moon and the planets.

The best time to observe a passing satellite is after sunset and before dawn. Then our side of the earth is turned away from the sun and the sky above us is not illumined with its radiant light. When the sun is in the sky, its brilliant light out dazzles and out¬ shines lesser lights in the sky. After sunset, a satellite is high enough to be in full view of the sun. The sunlight that falls upon it is reflected and some of it reaches us down on the ground. The light is on, not in, a satellite.