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 bigger body. So when a satellite is held in orbit, it is orbiting relative to a bigger body. An example is the Moon. Our Moon orbits the Earth. It is smaller than the Earth. So, the Moon would be an example of a satellite that orbits the Earth (the bigger body).

Geosynchronous satellites are man-made satellites that orbit the Earth. They always orbit the Earth at the same altitude (35,785 kilometers). 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 day. So a satellite in geosynchronous orbit appears to hover over a single location on Earth.

Scientists can use geosynchronous satellites to map the weather that happens everyday in a region on Earth. These satellites are good at that because they always look at one place on the Earth's surface.

Submitted by Elliott (England)
(September 30, 1997)


You might also be interested in:

What are the retrograde motions of planets in the sky?

It depends on which type of motion you are asking about. If you take a birds-eye view from the top of the solar system all the planets orbit around the Sun in a counter-clockwise (or direct) direction....more

How do Astronauts Live in Space?

Almost everyone has a question or two about living in space. What do astronauts do in space? How do they do everyday things like eat, sleep and go to the bathroom? It's important to note that astronauts...more

How far is the Earth from the Sun, the Moon and all the other planets? How far are all of the planets from the Sun? Do you know of a software that tracks the planets in real-time?

There is a really neat internet program called Solar System Live that shows the position of all of the planets and the Sun for any given day. If you go to that page, you'll see an image similar to the...more

Is it really true that man never really walked on the Moon?

The picture of the American Flag (the one put there by the Apollo astronauts) is waving (or straight out) in the wind. How could that be possible if there is no atmosphere on the Moon? Was it some sort...more

How many planets orbit the sun?

I was wondering if there is a new planet? Are there planets (a tenth planet?) after Pluto belonging to our solar system? What are the names of the new planets discovered in the solar system? Are there...more

According to Stephen Hawking, any object with an energy which equals Plank's energy has to become a black hole.

If that is so, the energy released during the Big Bang must have created many such black holes. Therefore most of the Energy of the Big bang must have disappeared in that form. Then how did the Universe...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA