geostationary orbit In an ideal geostationary orbit, a satellite revolves around the Earth in a circular orbit in the equatorial plane such that the period of revolution of the satellite is exactly equal to the period of rotation of Earth about its own axis, i.e. 23 h 56 min 4.09 s. The radius of the orbit from the center of the Earth can be calculated equating the centrifugal force ms w 2 r, and the gravitational attraction of Earth on the satellite. The value of r thus obtained is 42 300km. Subtracting the equatorial radius, 6400 km we obtain the altitude of the geostationary orbit equal to 35 900km. The advantage of such a satellite is that the antenna system do not need continuous tracking, because the satellite appears stationary from Earth. Only three such satellites can cover the whole Earth except small areas around North and South Pole. A geostationary satellite has several areas of applications, such as communications, meteorology etc.
(Note that for geostationary satellite square of time period of oscillation is proportional to the cube of radius of the orbit.)