Satellite Facts



  • Satellites are objects that orbit planets and other space objects. Moons are natural satellites. Spacecraft sent up to orbit the Earth and the Sun are artificial satellites.
  • The first artificial satellite was Sputnik 1, launched on 4 October 1957.
  • About 100 artificial satellites are now launched every year. A few of them are space telescopes.
  • Communications satellites beam everything from TV pictures to telephone calls around the world.
  • Observation satellites scan the Earth and are used for purposes such as scientific research, weather forecasting and spying.
  • Navigation satellites such as the Global Positioning System (GPS) are used by people such as airline pilots to work out exactly where they are.
  • Satellites are launched at a particular speed and trajectory (path) to place them in just the right orbit.
  • The lower a satellite’s orbit, the faster it must fly to avoid falling back to Earth. Most satellites fly in low orbits, 500 km above the Earth.
  • A geostationary orbit is 35,786 km up. Satellites in geostationary orbit over the Equator always stay in exactly the same place above the Earth.
  • Polar orbiting satellites circle the Earth from pole to pole about 850 km up, covering a different strip of the Earth’s surface on each orbit.
  • Communications satellites act as relay stations, receiving signals from one location and transmitting them to another.
  • One of the many hundreds of satellites now in Earth’s orbit.