When a satellite is held in orbit, what is it orbiting relative
to? What's so special about the orbit of geosynchronous
satellites? Well, you're on to something, Elliott. The Space
Satellite Handbook defines a satellite as a small body orbiting
a larger body. So when a satellite is held in orbit, it is
orbiting relative to a larger body. An example is the Surveyor
probe which just entered into orbit around Mars. The Surveyor is
a satellite in this system because it orbits Mars (the larger
body). Geosynchronous satellites are those man-made satellites
which always orbit the Earth at an altitude of 35,785 kilometers
(22,236 miles). But that's not all that is special about these
satellites. These satellites revolve around the Earth at the
same speed at which the Earth rotates, or geosynchronous
satellites complete one orbit in exactly one Earth day. Because
the orbital velocity matches the spin rate of the Earth, a
satellite in geosynchronous orbit appears to hover motionless
over a single location on Earth. Bec