8.2.3Space Physics

Orbiting Bodies — Oxford AQA International GCSE Combined Science - Physics Revision Notes & Topical Questions

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Part 1 of 5What orbits what

What they are

What they are An artificial satellite is a human-made object placed in orbit around the Earth, for example to carry communication signals.
Satellites are mainly put into either a geostationary orbit or a low polar orbit.

Geostationary orbit

Position

Position The satellite orbits above the Earth's equator at a height of about 36 000 km, far higher than a polar satellite.

Orbital period

Orbital period One orbit takes 24 hours, the same as the Earth's rotation, so the satellite stays above the same point on the surface.

Uses

Uses Radio and telecommunication broadcasting, including satellite television and some satellite phones.
- The very high orbit gives coverage of a huge area.

Polar orbit

Position

Position The satellite passes over the North and South Poles at a low height, around 200 km above sea level.

Advantages

Advantages Signals have a much shorter time delay than from a geostationary satellite, and images are much clearer because the satellite is closer.

Uses

Uses Monitoring the weather, military applications, taking images of the Earth's surface, and some satellite phones that need a more detailed signal.

Limitation

Limitation Each satellite sees a given place only briefly, so more than one satellite is needed for continuous operation.

Feature	Geostationary	Polar
Height	About 36 000 km	About 200 km
Path	Above the equator	Over the North and South Poles
Time for one orbit	24 hours	Much shorter
Signal delay	Longer	Shorter
Typical use	Broadcasting and telecommunications	Weather, imaging and monitoring

Term	Meaning
Orbit	The curved path followed by one object around another because of gravity.
Natural satellite	A moon, which orbits a planet.
Artificial satellite	A human-made object that orbits the Earth.
Geostationary orbit	An orbit above the equator with a period of 24 hours, so the satellite stays above one point on Earth.
Polar orbit	A low orbit that passes over the Earth's North and South Poles.
Comet	A small body of ice and dust that orbits the Sun.

Saying the Moon orbits the Sun. The Moon orbits the Earth, a planet; it travels with the Earth round the Sun.

Thinking a geostationary satellite does not move. It is orbiting, but its 24 hour period matches the Earth's rotation.

Placing geostationary satellites over the poles. They must be above the equator.

Mixing up the heights. The geostationary orbit is much higher than the polar orbit, which is why the signal delay is longer.

Forgetting that a single polar satellite cannot give continuous coverage of one place.

Last updated: 20 October 2026