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Geostationary orbit

A circular orbit about 35,786 km above the equator where a satellite's orbital period matches Earth's rotation, so it appears to hang motionless in the sky.

Why it matters

A satellite that never moves relative to the ground means a dish that never has to move either - which is the entire economics of satellite television, and much of weather and communications. The cost is distance: the round trip adds roughly a quarter of a second of latency, which is fine for broadcast and unacceptable for interactive use. It is also a finite resource. There are only so many usable slots along one equatorial ring, and they are allocated internationally rather than claimed.

In our data

Very few missions in our tracker list geostationary orbit as their final destination (3), but that undercounts it badly: 23 more are logged as geostationary transfer orbit, the elliptical staging orbit from which the satellite raises itself the rest of the way using its own propulsion. Reading the manifest literally would make geostationary traffic look about six times smaller than it is.

Where we use it

Not to be confused with

Geosynchronous orbit, which shares the 24-hour period but need not sit over the equator - a geosynchronous satellite traces a figure-of-eight in the sky rather than staying put. Every geostationary orbit is geosynchronous; the reverse is not true.