|Communications - SATELLITES|
| By : Gurpreet Kaur||Previous | Next|
| Posted on : 02 Sep, 2005 ||Total Views : 2978|
Satellite, in astronomy, secondary object that revolves in a closed orbit about a planet or star, referred to as the primary of the satellite. The best-known satellite is the earth's moon—just as the earth itself is a satellite of the sun—although the moon and earth are close enough in size to be considered sometimes as a double-planet system. The motion of most of the solar system's known satellites about their planets is direct—that is, from west to east—and in the same direction as the rotation of their planets. Only a few satellites of the large outer planets revolve in the retrograde direction—that is, from east to west—and opposite the direction of rotation of their planets; they probably were captured by the planets' gravitational fields some time after the formation of the solar system. Many astronomers believe that Pluto, which moves in an independent orbit about the sun, is an escaped satellite of Neptune; Pluto itself was recently discovered to have a satellite. Information about the individual satellites is given in the articles on the planets that they orbit.
Communication Satellite Corporation (COMSAT) planned to launch Aerocom in 1967 to provide voice communications for commercial aircraft flying the Atlantic route, where conventional radio links are relatively poor. Transmission of data from one computer installation to another thousands of miles away is possible with communications satellites. Television transmission of entertainment, interviews, and news events between United States and Europe have already been carried by the Early Bird satellite and its predecessors, Telstar, Relay, and Syncom.
Two other future applications of earth satellites are under development at several leading electronics firms. Meteorological information from a worldwide network of weather observation stations will be collected by a chain of communications satellites. These data will be fed to a master computer complex which will chart the weather pattern around the world. Educational television programs can be transmitted from one satellite and cover an area greater than several states. Schoolchildren in underdeveloped countries could receive the finest in lectures and demonstrations at an expense considerably lower than that needed to staff and supply hundreds of small schoolhouses.