Eric Ritter, age 10, of Wilmington, N.C., for his question:

WHAT IS PEGASUS?

Pegasus is a constellation found in the Northern Celestial Hemisphere. It can be seen high in the evening sky of autumn.

A large square called the Great Square of Pegasus marks the constellation in the sky. A line drawn down the east side of the square and extended an equal distance south indicates the point where the sun stands on March 21, the day spring begins.

The name Pegasus comes from the mythical Greek winged horse that was turned into a constellation by the god Zeus.

A legend says the Muses were holding a song contest. The music charmed the streams and made Mount Helicon grow toward the heavens. The god Poseidon ordered Pegasus to make it stop growing by striking it with his hoof. Pegasus did this and the fountain of Hippocrene sprang forth. Its waters inspired people to write poetry.