<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit . Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as Earth's Moon . </P> <P> In 1957 the Soviet Union launched the world's first artificial satellite, Sputnik 1 . Since then, about 6,600 satellites from more than 40 countries have been launched . According to a 2013 estimate, 3,600 remained in orbit . Of those, about 1,000 were operational; while the rest have lived out their useful lives and become space debris . Approximately 500 operational satellites are in low - Earth orbit, 50 are in medium - Earth orbit (at 20,000 km), and the rest are in geostationary orbit (at 36,000 km). A few large satellites have been launched in parts and assembled in orbit . Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, a comet and the Sun . </P>

What is the name of the satellite that orbits earth