![]() ![]() Objects farther away take longer for each orbit. This is why objects in low orbit (like the International Space Station orbit the Earth very quickly, about 90 minutes or so for each orbit. Objects closer to Earth feel more gravity. An orbit is a balance between centripetal force against the Earth's gravity. The height of the orbit is an exact distance, because the speed of the orbit depends on how far it is from the center of the Earth. (Geosynchronous orbits are like geostationary orbits, but also include those that go above and below the equator). So if it is directly above the equator, it doesn't move north or south at all. It needs to spend an equal amount of time on each side of the equator. ![]() Since all orbits are around the center of the Earth, if it was tipped above the equator (so that the satellite was straight above New York City, for example) it would need to swing an equal distance to the south pole on each orbit. The satellite orbits in the direction of the Earth's rotation, producing an orbital period equal to the Earth's period of rotation, known as the sidereal day (very nearly 24 hours). The Clarke Orbit (another name for a geostationary orbit) is about 265,000 km (165,000 mi) around.ĭetails of the orbit Named after the author, the Clarke Belt is this part of space above the Earth - about 35,786 km (22,000 mi) above sea level, over the equator, where near-geostationary orbits may be implemented. The orbit, which Clarke first described as good for broadcast and relay communications satellites, is sometimes called the Clarke Orbit. Clarke, published in Wireless World magazine. The idea of a geostationary orbit became well known first in a 1945 paper called "Extra-Terrestrial Relays - Can Rocket Stations Give Worldwide Radio Coverage?" by the British science fiction writer Arthur C. The idea of a geosynchronous satellite for communication was first published in 1928 (but not widely so) by Herman Potočnik. Each one stays above the equator at a set longitude (distance east or west). This is cheaper and easier than having a satellite dish that is always moving to track a satellite. The ground atennas can be pointed permanently at a fixed position in the sky. Satellites in geostationary orbit Ĭommunications satellites and weather satellites often use these orbits, so that the satellite antennas that communicate with them do not have to move to track them.
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