Understanding satellite orbits
A satellite does not fall straight to Earth because its sideways velocity turns free fall into motion around the planet. Orbital height and shape determine its period and viewing area.
Low and medium orbits
Low Earth orbit (LEO) is used for Earth observation, crewed stations and many communications networks. Objects cross the sky quickly, so continuous coverage requires a constellation. Many navigation systems use medium Earth orbit (MEO): each satellite can be seen across a wider area, though its signal travels farther.
Geosynchronous and elliptical orbits
A geosynchronous spacecraft circles Earth in approximately one rotation of the planet. A geostationary orbit is a special circular equatorial case in which the spacecraft stays almost fixed in the observer’s sky. Highly elliptical orbits (HEO) change altitude and speed substantially during each revolution.
Above Us groups objects by orbit class to make exploration easier. A calculated orbital line depends on the elements and selected time; it is not a guaranteed path indefinitely into the future.