Satellites are orbiting our planet constantly providing us services such as, internet, telecommunications, and weather data. There are three primary classes of orbits around the Earth: Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and High Earth Orbit; also known as geosynchronous/geostationary orbit (GEO).
Orbit of a Geostationary Satellite shown by red dots
High Earth Orbit, or what we are going to call it for the rest of the article geostationary orbit (GEO), is when a satellite reaches about 36,000 kilometers (22,369.4 miles) from Earth’s surface and is along the equator. The name geostationary comes from the satellite being overtop the exact same location of the Earth’s surface. The satellite is able to stay “stationary” because the satellite is travelling at the same rate as Earth’s rotation, allowing it to remain in the same location. Types of satellites that reside in this orbit are telecommunication satellites and weather monitoring systems. GEO allows satellites to cover a large area of Earth’s surface and allows for better weather data collection. GEO enables companies, organizations, and countries to put fewer satellites into orbit to cover an area than if they were to place them in lower orbit paths.
Medium Earth Orbit (MEO) is between 1000 km (621.4 miles) and 35000 km (21748 miles) from the surface of Earth but most satellites in MEO are about 20,200 km (12551.7 miles) up. Satellites that are in MEO cross the same position twice a day as their orbit time is 12 hours. Global Positioning System (GPS) satellites reside in MEO.
Low Earth Orbit (LEO) is the most common orbit that satellites reside in. LEO can be as low as 140 km (87 miles) or as high as 1000 km (621.4 miles) away from the surface of Earth. Satellites in this orbit travel around the Earth very fast and have orbit times ranging from 90 minutes to two hours. LEO hosts a collection of satellite types. Imaging satellites, telecommunication satellites (travel in satellite constellations), CubeSats, and even the International Space Station (ISS) are all in LEO.
Image of International Space Station
Credit: NASA
Other Resources:
Popular Orbits 101
NASA - Catalog of Earth Satellite Orbits
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