The first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth. These originate from more than 50 countries and have used the satellite launching capabilities of ten nations. A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Venus, Mars, Jupiter and Saturn.

Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.

Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control and orbit control.
 

First launch by country:
1 Soviet Union 1957 - Sputnik-PS Sputnik 1
2 United States 1958 - Juno I Explorer 1
3 France 1965 - Diamant Astérix
4 Japan 1970 - Lambda-4S Ōsumi
5 China 1970 - Long March 1 Dong Fang Hong I
6 United Kingdom 1971 - Black Arrow Prospero X-3"
7 India 1980 - SLV Rohini
8 Israel 1988 - Shavit Ofeq 1
- Russia 1992 - Soyuz-U Kosmos 2175
- Ukraine 1992 - Tsyklon-3 Strela
9 Iran 2009 - Safir-2 Omid

 

These websites provide a list of satellites or other objects that are orbiting around our planet:

• http://nssdc.gsfc.nasa.gov/nmc/
• http://www.satsig.net/sslist.htm
• http://usspaceobjectsregistry.state.gov/search/index.cfm
• http://celestrak.com/