Geostationary Orbit

The second orbit used by communications satellites is geostationary orbit. The word “geostationary” means that the satellite does not move in relation to a point on the Earth. A geostationary satellite – also called a “GEO” satellite – orbits the Earth in about 24 hours, which is the same time that it takes for the Earth to rotate one time. If the satellite is placed above the equator and orbits in the same direction and the same speed as the Earth turns – about 7,000 miles per hour - then the satellite will appear stationary in the sky relative to a point on the Earth's surface.

Because the satellite does not appear to move in the sky, it is not necessary to re-point an antenna constantly to communicate with a GEO satellite . For example, a satellite television antenna, or “dish”, is pointed towards a particular satellite once during the initial installation, but then does not need to be re-pointed in the future.

In order to orbit the Earth in 24 hours, a satellite has to be placed in an orbit 22,237 miles above the Earth. Any lower or higher and the satellite's orbit will be faster or slower than the rotation of the Earth. A single GEO satellite can “see” about 1/3 of the Earth's surface, but is generally unable to reach far north and far south locations.