Definition
According to Kepler's Third Law, the orbital period of a satellite in a circular orbit increases with increasing altitude. Space stations and Shuttles in Low Earth orbit (LEO), typically two to four hundred miles above the Earth's surface, make between fifteen and sixteen revolutions per day. The Moon, at an altitude of about 238,900 miles (384,400 km), takes about 27 days 7 hours to make a complete revolution. Between those extremes lies the "magic" altitude of 22,236 miles (35,786 km) at which a satellite's orbital period matches the period at which the Earth rotates: once every sidereal day (23 hours 56 minutes 4 seconds). In that case, the satellite is said to be geosynchronous.
If a geosynchronous satellite's orbit is not exactly aligned with the Earth's equator, the orbit is known as an inclined orbit. It will appear (when viewed by someone on the ground) to oscillate daily around a fixed point. As the angle between the orbit and the equator decreases, the magnitude of this oscillation becomes smaller; when the orbit lies entirely over the equator, assuming a circular orbit, the satellite remains stationary relative to the Earth's surface – it is said to be geostationary.
Read more about this topic: Geosynchronous Satellite
Famous quotes containing the word definition:
“The definition of good prose is proper words in their proper places; of good verse, the most proper words in their proper places. The propriety is in either case relative. The words in prose ought to express the intended meaning, and no more; if they attract attention to themselves, it is, in general, a fault.”
—Samuel Taylor Coleridge (1772–1834)
“... if, as women, we accept a philosophy of history that asserts that women are by definition assimilated into the male universal, that we can understand our past through a male lens—if we are unaware that women even have a history—we live our lives similarly unanchored, drifting in response to a veering wind of myth and bias.”
—Adrienne Rich (b. 1929)
“The very definition of the real becomes: that of which it is possible to give an equivalent reproduction.... The real is not only what can be reproduced, but that which is always already reproduced. The hyperreal.”
—Jean Baudrillard (b. 1929)