Why Do Satellites Use Geosynchronous Orbit?

A geosynchronous orbit allows a satellite to stay in the same position relative to the surface of the Earth at all times. It is therefore very useful for communications satellites.

Geosynchronous and Geostationary

A geosynchronous orbit is, technically, any one that has the same duration as the rotation of the Earth. That isn't what is usually meant, however, by the phrase.

What We Mean Is Geostationary

A geostationary orbit is one where the satellite is in geosynchronous orbit but in a nearly circular orbit and around the equator or near it. This is where almost all communications satellites are.

We San Do It Snother Way

It is possible to run satellite communications using low-Earth orbits, but this requires many more satellites and can thus be much more expensive.

The Reason We Use Geostationary Orbits

Geostationary orbits are used so that satellites sit above one place on the Earth. This makes it much easier to send telephone, radio, TV and other signals to them and for them to be sent back down again. They're always in the same place.

Where is a Geosynchronous Orbit?

Obviously, it's in space--in more detail, a geostationary orbit is at 22,200 miles or so above the surface of the Earth. Because the Earth is not perfectly round a geosynchronous one can be a little lower than this.

References

• Science Daily: Geosynchronous Orbits

Resources

• Braeunig.us: Guide to Orbital Mechanics