Satellites in Earth orbit, illustration. Satellite functions and uses range from Earth observation satellites (including weather and environmental satellites) to military and research satellites. The orbits of the satellites can take different forms: heliosynchronous, geostationary, elliptical or circular. They can also be classified by altitude: low, medium or high orbit. The first artificial satellite (Sputnik 1) was launched in 1957. Since then, over 8000 have been launched, with about 5000 in orbit as of 2020.