Geostationary Satellite

The satellite which appears stationary relative to earth is called geostationary or geosynchronous satellite, communication satellite. A geostationary satellite always stays over the same place above the earth such a satellite is never at rest. Such a satellite appears stationary due to its zero relative velocity w.r.t. that place on earth.

The orbit of a geostationary satellite is known as the parking orbit.

Important points:

• It should revolve in an orbit concentric and coplanar with the equatorial plane.
• It sense of rotation should be same as that of earth about its own axis i.e., in anti - clockwise direction (from west to east).
• Its period of revolution around the earth should be same as that of earth about its own axis.
  T = 24 hrs. = 86400s
• Height of geostationary satellite
  As T = 2π √ (r³/ GM) ⇒ 2π √ [(R + h)³/ GM] = 24 hr.