An orbit in which a satellite moves around a planet in the same time as the planet takes to rotate on its axis. In the Earth’s case, a body in synchronous orbit has a period of one sidereal day and an average distance of 42 162 km from the Earth’s centre. If the orbit is circular and in the Earth’s equatorial plane, the satellite remains above a particular point on the equator. Such an orbit is called a geostationary orbit and is used for communication satellites. If the orbit is synchronous but in a plane inclined to the equator, the satellite appears to trace out a figure-of-eight each day, as seen from Earth. The centre of the figure-of-eight lies on the equator, and the loops of the figure-of-eight lie between latitudes equal to the orbit’s inclination to the equator.