| English | Geostationary orbit |
|---|---|
| Bahasa Melayu | Orbit geopegun |
| 中文 | 地球同步轨道 |
Definition
An orbit above the equator in which a satellite has a period of 24 hours, so it appears to stay above the same point on the Earth's surface.
In exam terms
A geostationary orbit is a circular orbit directly above the equator in which a satellite has an orbital period of exactly 24 hours, the same as the Earth's rotation. Because it moves in the same direction and at the same rate as the point below it, the satellite stays fixed above one spot on the surface.
This orbit lies at a fixed altitude of about 3.6 × 10⁷ m above the equator, and only one radius gives the 24 h period. For example, a communication satellite in a geostationary orbit can point a dish antenna at a single fixed direction, because the satellite never appears to move across the sky.
Do not confuse it with…
Do not confuse a geostationary orbit with a general satellite orbit. Any satellite orbit balances gravitational pull against the centripetal requirement, but only the geostationary orbit has a 24 h period above the equator so the satellite appears stationary.
A low polar orbit has a much shorter period and sweeps across the ground.
In Paper 2 this is asked as state two characteristics of a geostationary orbit or explain why a geostationary satellite appears stationary. The key points are: period equals Earth's rotation period of 24 h, orbit is above the equator, and it moves in the same direction as the Earth's spin.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)