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Polar and low Earth orbits
Beginner
Used for imaging and the International Space Station.
Low orbits (200–2000 km) give high resolution and short periods; polar orbits pass over both poles and eventually scan the entire planet.
Earth-observation satellites at about 700 km.
Low orbits suffer drag.
In more detail
Low Earth orbits are typically 200 to 2,000 km high, and polar orbits pass over both poles. Polar orbits allow satellites to scan the whole globe as Earth rotates.
Real-world uses
- Earth observation and mapping satellites use polar orbits.
- Space stations occupy low Earth orbit for easy resupply.
- Earth-observation satellites use low polar orbits to map the whole surface as the planet turns beneath them.
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Frequently asked questions
Why are polar orbits useful?
They cover nearly all of Earth's surface over time as the planet rotates beneath them.
How long does a low Earth orbit take?
About 90 minutes for a typical low orbit.
Why are low orbits used for imaging?
They are close to the ground, which gives sharper images, and they pass over most places regularly.
Related topics in Gravitation & Orbits
Satellite energy · Orbital period · Geostationary satellites · Weightlessness in orbit · Kepler's first law · Kepler's second law