A manufactured object placed in orbit round the Earth or some other celestial body. The first artificial satellite to be placed in orbit round the Earth was the Soviet Sputnik 1, launched on 4 October 1957.
Artificial Earth Satellites leaves a very wide range of uses at the present time, including the following: astronomical observatories (studying wavelengths of radiation which cannot penetrate the atmosphere); scientific satellites (studying the upper atmosphere, and near-Earth environment); geodesy (studying the shape and structure of the Earth); Earth resources: meteorology; communications (television, telephone, etc); navigational aids; military reconnaissance.
