We got Richard F., to help us with your question.

To an astronomer, a satellite is anything that orbits around a planet. The Moon is the Earth's biggest satellite. But you probably wanted to know about man-made satellites.

What keeps any satellite in orbit? First, any object in space keeps on moving at a constant speed in a straight line unless something (called a force) makes it change. For any satellite of a planet, the force is gravity, which makes the satellite fall towards the planet. If the satellite started out standing still, it would just fall back to Earth. But it doesn't because it is moving rapidly sideways. It moves so fast that by the time it would have fallen, it is partway around the orbit.

Anyway, man-made satellites are actually machines, put into orbit by rockets. Most of them have radio transmitters. Some have radio receivers, some have cameras, some have telescopes, and so on It depends what job they were designed to do. Usually, they get their energy from solar cells which are turned to face the sun.

Pierre Kerr, ac210@freenet.carleton.ca, adds...

One of the uses of satellites is to take pictures of the Earth. If you watch the weather on TV, you will probably see satellite pictures showing clouds. Here is a picture I got from the InterNet showing a satellite's view of a hurricane. As well is a typical weather picture with lines added by the weatherman.

Answer #% % filename Document4 page% % page 1 of% % numpages 1 % % date \@ "MMMM d, yyyy"April 10, 1995