Is There Gravity in Orbit?
Is There Gravity in Orbit?|
Yes! A spacecraft in orbit is not beyond the reach of
Earth's gravity. In fact, gravity is what holds it in orbit--
without gravity, the spacecraft would fly off in a straight path.
As the spacecraft orbits, it is actually falling, though it never
reaches the ground. Imagine a cannon firing balls with different speeds. The faster a ball's speed, the farther it travels. With enough speed, a ball travels so far that its landing point depends on the Earth's curvature. With even more speed, the curve of its path will match that of the Earth's surface. With no drag to slow it, the ball will continue to fall but never reach the ground. Imagine standing on a small asteroid that has far less gravity than the Earth and no air to cause drag. Here you could actually pitch a baseball into a complete orbit. After throwing the ball, you could turn around, wait about two hours, and catch it as it comes up over the opposite horizon! |
 |
 |
 |
 |
(Rev. 09/19/96)