A satellite is a machine placed in space orbit in order to carry out some specific tasks.
Satellites which orbit the Earth can be used for many jobs, including:
- Television broadcasting
- Scientific research
The satellite sends and receives signals using transponders.
Satellites generally are in two kinds of orbit - LEO Low Earth Orbit which is used for rapidly changing requirements such as GPS (Global Positioning System) or Military where fine detail is needed in real time.
The other is geosynchronous orbit. This is used where it is important that the apparent position in the sky does not change. For example, Sky Television has millions of satellite dishes screwed to the wall of individual houses. So it is vital that the Sky satellites do not move in the sky!
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Click on this link: Satellite