Editing Geosynchronous orbit (section)

{{short description|Orbit keeping the satellite at a fixed longitude above the equator}}
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[[File:Geosynchronous orbit.gif|thumb|upright=1.3|Animation (not to scale) showing geosynchronous satellite orbiting the Earth]]

A '''geosynchronous orbit''' (sometimes abbreviated '''GSO''') is an Earth-centered [[orbit]] with an [[orbital period]] that matches [[Earth's rotation]] on its axis, 23 hours, 56 minutes, and 4 seconds (one [[sidereal day]]). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day. Over the course of a day, the object's position in the sky may remain still or trace out a path, [[Analemma#Of geosynchronous satellites|typically in a figure-8 form]], whose precise characteristics depend on the orbit's [[Orbital inclination|inclination]] and [[Orbital eccentricity|eccentricity]]. A circular geosynchronous orbit has a constant altitude of {{convert|35786|km|mi|0|abbr=on}}.<ref name=sdc20150426>{{cite news |last=Howell |first=Elizabeth |title=What Is a Geosynchronous Orbit? |url=https://www.space.com/29222-geosynchronous-orbit.html |work=Space.com |access-date=15 July 2022}}</ref>

A special case of geosynchronous orbit is the [[geostationary orbit]] (often abbreviated ''GEO''), which is a circular geosynchronous orbit in Earth's [[equatorial plane]] with both inclination and eccentricity equal to 0. A satellite in a geostationary orbit remains in the same position in the sky to observers on the surface.<ref name=sdc20150426 />

[[Communications satellite]]s are often given geostationary or close-to-geostationary orbits, so that the [[satellite antenna]]s that communicate with them do not have to move but can be pointed permanently at the fixed location in the sky where the satellite appears.<ref name=sdc20150426 />