Hubble uses some very basic physics to turn itself around and look at different parts of the sky. Located on the telescope are six gyroscopes (which, like a compass, always point in the same direction) and four free-spinning steering devices called reaction wheels.
The gyroscopes sense when the telescope needs to be repointed. When they "tell" Hubble that it needs to turn itself, a computer gives a command to give the reaction wheels a "push" or "spin."
