Steve Middlebrook, age 10, of Bartlesville, Oklahoma, for his question:

Is gravity stronger at the poles or the equator?

The force of gravity seems to come from the very center of our planet, getting weaker as it goes. Now if our planet were a perfect globe, the distance from the center to any point on the surface would be exactly the same. In that case, gravity at the earth's surface would be exactly the same all over the world. But it so happens that the earth is not quite a perfectly round sphere. This makes a slight difference between gravity at the equator and gravity at the poles.

Actually our round earth bulges a bit around the waistline, which is the equator. The distance around the equator is about 42 miles longer than a global circle through the poles. This makes the poles about 14 miles closer to the center of gravity in the middle of the earth. So, when standing on the North or South Pole, you weigh a little more than you do at the equator. This is because gravity is a tiny bit weaker at the equator