Yeah there are many, but the two you will hear about the most are LEO and GSO.
LEO is Low Earth Orbit, and is basically right at the edge of space. This is close enough that they can bounce signals around the Earth quickly, but far enough that there is not a lot of atmosphere. These tend to fall out of space pretty easily unless they have some onboard boosters to adjust their orbit, as otherwise the thin air does eventually slow them down.
GSO is Geo-Synchronous Orbit, and is far enough away that the orbital period is perfectly matched to the earth’s rotation. That can be useful for all sorts of reasons, such as maintaining continuous contact above a fixed point on the equator.
It should be noted that geosynchronous and geostationary are not the same. Geosynchronous does mean that it orbits the earth at 1 rotation per day, but depending on inclination and/or eccentricity, it doesn’t stay still, it will draw out a slow loop or figure-8 from any given observer’s perspective. The latter thing you’re describing is a geostationary orbit; satellites in a geosynchronous orbit above the equatorial plane, with 0 inclination and eccentricity, stay at exactly the same spot in the sky at all times, and are said to be geostationary, or to be in GEO (rather than GSO).
Yeah there are many, but the two you will hear about the most are LEO and GSO.
LEO is Low Earth Orbit, and is basically right at the edge of space. This is close enough that they can bounce signals around the Earth quickly, but far enough that there is not a lot of atmosphere. These tend to fall out of space pretty easily unless they have some onboard boosters to adjust their orbit, as otherwise the thin air does eventually slow them down.
GSO is Geo-Synchronous Orbit, and is far enough away that the orbital period is perfectly matched to the earth’s rotation. That can be useful for all sorts of reasons, such as maintaining continuous contact above a fixed point on the equator.
It should be noted that geosynchronous and geostationary are not the same. Geosynchronous does mean that it orbits the earth at 1 rotation per day, but depending on inclination and/or eccentricity, it doesn’t stay still, it will draw out a slow loop or figure-8 from any given observer’s perspective. The latter thing you’re describing is a geostationary orbit; satellites in a geosynchronous orbit above the equatorial plane, with 0 inclination and eccentricity, stay at exactly the same spot in the sky at all times, and are said to be geostationary, or to be in GEO (rather than GSO).
It should also be noted that the documentary Independence Day showed us that all our satellites will be used against us when the aliens invade.
"We will not go slowly into the night! "
There are also the various Lagrange points that allow two or more orbiting bodies to stay stationary in relation to each other.