Andy Kessler, age 13, of St. Augustine, Fla. for his question:

DOES THE 'EVENING STAR' HAVE ANOTHER NAME?

What we call the "evening star" is not a star at all. It is a planet that can be seen just after sunset. The planets Venus and Mercury are most often seen as evening stars.

Because these two planets move in orbits smaller than the earth's orbit, they appear to move from one side of the sun to the other. The two planets can be seen only in the western sky after sunset or in the eastern sky before sunrise.

When either planet is seen at sunrise, it is usually called a "morning star."

Planets are not really stars, but members of our own solar system. They do not give off their own light as stars do. They shine by reflecting sunlight. The sun is a star.

Ancient people thought planets were wandering stars. They did not realize that the planet seen in the evening was the same planet they saw in the morning. Therefore, they gave the evening and morning stars different names. The Greeks called Venus "Hesperus" as an evening star and "Phosphorus" as a morning star.

The Romans called it "Vesper" as an evening star and "Lucifer" as the morning star. Mercury was called by its present name as an evening star, but "Apollo" as a morning star.