Ask someone why astronauts in the Space Shuttle or the MIR space station
float in their cabins, and quite often you'll hear that it's because there's
zero gravity in space. This kinda makes sense, doesn't it? After all, the
space travelers are about hundred miles above the Earth's surface, right?
Actually, that answer is completely wrong.
It is true that the pull of gravity is less on the astronauts and their
craft, but the pull is only slightly less. With the center of the Earth
3,960 miles away from someone standing on the surface and 4,060 miles away
from someone orbiting 100 miles above, the difference in the pull of gravity
is only about 5 percent. That means if you weigh 100 pounds on Earth, you
would weigh 95 when 100 miles high.
No, the real reason that astronauts float around is that they're in a
continuous free fall. To find out exactly how this works, check out "the
full explanation" below, starting with Part 1. If you want more of a
challenge, skip right to "just the activities" and see if you can figure it