Other Types of Orbit: Medium, Geostationary and High Earth Orbit
Other types of circular orbits include the Medium, the Geostationary and the High Earth Orbit:
The Medium Earth Orbit or MEO lies between the Low Earth Orbit and the Geostationary Orbit (see below) at an altitude of 2,000 km to 35,900 km.
A Geosynchronous or Geostationary Earth Orbit or GEO is a circular orbit around the Earth at the altitude of 35,786 km. At this altitude, the geostationary satellite travels at the same speed as the Earth rotates, making a 24-hour orbit around the Earth and can be seen to stay or hover over the same place above the Equator. This kind of orbit is used for communication and weather satellites. The first satellite to be placed into geostationary orbit was Syncom 3 in 1964.
There is a difference between a geosynchronous and a geostationary orbit. A satellite with a geostationary orbit is circling the Earth in the equatorial plane, in the same direction of Earth's rotation and therefore appears stationary above the same point on the Earth's surface. In this case the time period for a full revolution takes 24 hours. A geosynchronous orbit is a more general term and refers to an orbit that places a satellite over the same spot on the Earth once every day.
The High Earth Orbit or HEO extends over the geostationary limit of 35,786 km.
Image: Zone 1: Earth, Zone 2: Low Earth orbit, Zone 3: Medium earth orbit, Zone 4: Geosynchronous earth orbit.