Scott Grover, age 11, of San Diego, Calif., for his question:

How far is the moon from the earth?

The path of the moon is slightly irregular, and sometimes it swings nearer and sometimes farther from the earth. At its nearest point, which is called the perigee of its orbit, the moon and the earth are only 226,000 miles apart. At the farthest point, which is the apogee of its orbit, the moon and the earth are separated by 252,000 miles.

The mean or average distance between the earth and its satellite is 239,000 miles. At 60 miles an hour, you could travel this distance in dust under 166 days. At 1200 miles an hour, a rocket could travel this distance in eight and a half days. A non stop walking trip at three miles an hour would take nine years and a month.