• A satellite is a body that orbits round a planet.
• The moon is a satellite of the earth.
• The number of satellites or moons of the planets are listed below:
  

  Planets	Number of Moons/Satellites
  Mercury	None
  Venus	None
  Mars	2
  Earth	1
  Jupiter	79
  Saturn	82
  Uranus	27
  Neptune	14

Natural and Artificial Satellites

Examples of Natural Satellites (Photo Credit: SlidePlayer.com)

• All the moons that orbit the planets in our solar system are natural satellites.
• Artificial satellites are human made bodies launched by various countries and are now orbiting the earth.
• Rockets are used to place satellites is space.
• Some countries which have so far independently launched satellites that orbit the earth are:
  

  Country	Year of First Launch	First Satellite
  Russia	1957	Sputnik 1
  U.S.A	1958	Explorer 1
  Britain	1964	Blue Streak
  France	1965	Asterix
  Japan	1970	Ohsumi
  China	1970	Dong Fang Hong 1
  U.K	1971	Prospero (X-3)
  India	1980	Rohini
  Israel	1988	Ofeq
  Nigeria	2003	SAT 1

• Artificial satellites differ from one another in the following ways:
  • Size.
  • Function.
  • Height or orbit round the earth.
  • Slope of orbit.
  • Speed of revolution round the earth.

An Example of an Artificial Satellite (Photo Credit: QKnowBooks.com)

Uses of Satellites

• Weather Satellites – These monitor the weather conditions in the atmosphere and supply the information to ground stations. This information helps to make accurate weather forecasts.
• Observation Satellites – are used for geographical studies such as photographing of areas, map making, census, and locating mineral deposits, etc.
• Communication Satellites – These satellites are sent into space for the purpose of sending information from one place to another.
• Reconnaissance Satellites – They are used for military or intelligence purposes such as locating enemy locations or troop movement.

Nigerian Surveillance Satellite

• Nigeria’s SAT 1 is called a surveillance satellite.
• It is used to observe happenings on the ground and also for geographical mappings of boundaries between states.