Loretta Peters, age 14, of Jamestown, N.Y., for her question:

WHAT IS AN ASTEROID?

An asteroid is an extremely small planet that revolves around the sun between the orbits of Mars and Jupiter. There are thousands of known asteroids and new ones are being discovered constantly.

About 30,000 asteroids are bright enough at one time or another to be photographed with medium sized telescopes. Astronomers have studied about 1,700 of them and know the orbits of these small planets well.

Asteroids vary greatly in size and most have irregular shapes. A total of about 20 asteroids have diameters that are larger than 100 miles

Ceres, the largest and first asteroid to be discovered, was first seen on January 1, 1801. It is about 480 miles in diameter. Pallas, Juno and Vesta are other well known large asteroids.

Eros was discovered in 1898. It has an irregular shape and is about 14 miles long and four miles wide. tcarus, one of the smallest asteroids, was discovered in 1949. 7t has a more regular shape than Eros has and is only about six tenths of a mile in diameter.