地球同步轨道（英语：Geosynchronous orbit，GSO），卫星的轨道周期等于地球的自转周期，且方向亦与之一致，见同步轨道。轨道平面与地球赤道平面重合，即卫星与地面的位置相对保持不变，则称为地球静止轨道。

实现地球同步轨道，需满足下列条件：

通讯卫星常使用于这种轨道，但导航卫星则否。

A geosynchronous orbit (sometimes abbreviated GSO) is an orbit around the Earth with an orbital period of one sidereal day, intentionally matching the Earth's sidereal rotation period (approximately 23 hours 56 minutes and 4 seconds). The synchronization of rotation and orbital period means that, for an observer on the surface of the Earth, 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 traces out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity.