A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body. In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... A satellite is an object that orbits another object (known as its primary). ...

A satellite in a synchronous orbit that is both equatorial and circular will appear to be suspended motionless above a point on the orbited planet's equator. However, a synchronous orbit need not be equatorial, nor circular. A body in a nonequatorial synchronous orbit will appear to oscillate north and south above a point on the planet's equator, while a body in an elliptical orbit will appear to oscillate eastward and westward. The combination of these two motions produces a figure-8 pattern as seen from the orbited body. The equator is an imaginary line drawn around a planet, halfway between the poles. ... In mathematics, an ellipse (from the Greek for absence) is a curve where the sum of the distances from any point on the curve to two fixed points is constant. ...

A synchronous orbit about the Earth that is circular and lies in the equatorial plane is called a geostationary orbit. A geostationary orbit (abbreviated GEO) is a circular orbit in the Earths equatorial plane, any point on which revolves about the Earth in the same direction and with the same period as the Earths rotation. ...

Source: From Federal Standard 1037C Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ...