Different Types of Orbits

Name A Star Live is an aerospace company that launches your star name and message into space: You are made part of an actual space mission! Indeed, we've been launching payloads into space for years, into a variety of orbits -- once even to the Moon!

Most of our missions have flown in "low Earth orbit" (or "LEO" for short). LEO's are orbits of anywhere from about 62 miles (100 km) to a few hundred miles/km in altitude. Space shuttles and the International Space Station fly in LEO, for example.

Orbits can be described not only by their altitude, but also by their orientation with respect to the Earth. For example, many satellites travel in "equatorial orbits" -- orbits that roughly parallel the Earth's equator. Generally speaking, such satellites fly in an easterly direction, such as NASA's space shuttles. They are launched in easterly directions so as to take advantage of the Earth's easterly rotation, and thus maximize the velocity of the satellite. But some satellites in equatorial orbits will fly in a westerly direction, and are therefore said to be in "retrograde orbits."

Satellites can travel in "polar orbits," where the satellites fly over the north and south polar regions. Vandenberg Air Force Base, California, and Kodiak Island, Alaska launch satellites into polar orbits.

	-
Equatorial orbit		Polar orbit

The moon as seen from the space shuttle Columbia in LEO, 2003. Credit: NASA

Sun-synchronous orbits are special polar orbits where the satellite flies in a fixed relationship to the sun. A satellite in a sun-synchronous orbit flies over a particular area of the Earth at the same time each day. Such orbits are useful for satellites studying the Earth’s environment, or for other remote sensing applications.

Geosynchronous earth orbits (“GEO” for short) are special equatorial orbits where the satellite flies in a fixed relationship with Earth. A satellite in GEO flies over a particular area of the Earth at all times of the day (not just at a particular time of the day, as with sun-synchronous satellites). Specifically, a satellite in GEO hovers at a ‘fixed’ point in space, relative to the Earth's equator. GEO satellites typically fly about 22,310 miles (35,900 km) above the equator: At this altitude, GEO satellites can 'see' almost the entire Earth (with the exception of the north and south poles). If you have satellite TV, the satellite dish on your roof is permanently pointed at a satellite in GEO. Because GEO satellites hover above the equator, if you live in the northern hemisphere of Earth your satellite TV dish is pointed southwards, but if you live in the southern hemisphere, your satellite TV dish is pointed northwards. Geosynchronous orbits are also called “geostationary orbits” or “Clarke orbits,” in honor of the late science fiction author Arthur C. Clarke, who first envisioned GEOs.

While there are other types of orbits, LEO, GEO, sun-synchronous, equatorial and polar orbits are the most common terms used in describing satellite orbits.