Geostationary Orbits (Cambridge (CIE) A Level Physics): Revision Note

Geostationary orbits

• Many communication satellites around Earth follow a geostationary orbit

• This is a specific type of orbit in which the satellite:

  • Remains directly above the equator, therefore, it always orbits at the same point above the Earth’s surface

  • Moves from west to east (same direction as the Earth spins)

  • Has an orbital time period equal to Earth’s rotational period of 24 hours

• Geostationary satellites are used for telecommunication transmissions (e.g. radio) and television broadcast

• A base station on Earth sends the TV signal up to the satellite where it is amplified and broadcast back to the ground to the desired locations

• The satellite receiver dishes on the Earth's surface must point towards the same point in the sky

  • Since the geostationary orbits of the satellites are fixed, the receiver dishes can be fixed too

Geostationary satellite in orbit

Satellite in geostationary orbit remain directly above the equator, and a circular orbit equal to that of the Earth