Sandra Bender, age 11, of Stratford, Conn., for her question:

Does Jupiter have an equator?

Every planet that revolves on its axis has an equator, and giant Jupiter revolves on its axis. The axis is an imaginary line through the center of the planet from pole to pole. Jupiter's equator, like the earth's equator, is exactly half way between these two poles. It is another imaginary line clear around the waist of the planet.

There is a big difference, however, between the earth's equator and Jupiter's equator. Our earth is about 24,000 miles around the waistline. Big fat Jupiter is about 267,000 miles around the middle. In spite of its great size, Jupiter rotates very fast on its axis, Its day and night period is equal to about ten earth hours. This spinning speed seems to have caused. the planet to flatten at the poles and bulge at the waist. For the; diameter of Jupiter at the equator is considerably longer than the diameter through the poles.