Don Ford, age 8, of Asheville, North Carolina, for his question:

How can they stand on the moon with no gravity?

Gravity is tricky and hard to understand. But naturally a young space ager wants to know all he can about it. We know that gravity hugs us to the ground, helps us to stand upright and walk, gives us weight and pulls down falling stones. This is mysterious because gravity is invisible. What's more, things get more mysterious out in space. We learn that its pull grows weaker as a spacecraft flies to the moon. Soon the astronauts inside can float around with no feeling of gravity at all.

When they reach the moon, we take it for granted that they feel none of the earth's gravity. Ah, but the moon has its own gravity. On the lunar surface, it acts the same way as the earth's gravity does right here. But there is one big difference. The earth's gravity is six times stronger than the moon's. This weaker lunar gravity pulls at the astronauts and helps them to stand upright. But because its pull is weaker, they can jump higher and take bigger strides, Its weaker pull also makes things lighter. For example, a boy who weighs 90 pounds on earth, on the moon his weight would be on sixth of 90 pounds which is only 15 pounds.  That would be his weight  on the moon!