Brandon Lee
Geostationary orbits. To an observer on the rotating Earth, both satellites appear stationary on the sky at their respective locations.
Geosynchronous Orbit: GEO
A geostationary orbit, or Geostationary Earth Orbit (GEO), is a circular orbit—in physics, the gravitationally curved path of an object around a point in space, for example, the orbit of a planet around the center of a star system, such as the Solar System. It is 35,786 km (22,000 mi) above the Earth’s equator, or the intersection of a sphere’s surface with the plane perpendicular to the sphere’s axis of rotation and containing the sphere’s center of mass. It also follows the direction of the Earth’s rotation.
An object in such an orbit has an orbital period equal to the Earth’s rotational period, or one sidereal day, a time-keeping system astronomers use to keep track of the direction to point their telescopes to view a given star in the night sky. Thus, it appears motionless, at a fixed position in the sky, to the ground observers.
Communications satellites (sometimes abbreviated to COMSAT), an artificial satellite stationed in space for the purpose of telecommunications, and weather satellites, a type of satellite that is primarily used to monitor the weather and climate of the Earth, are often given stationary orbits. It is so that the satellite antennas/dishes, a dish-spaced type of parabolic antenna designed to receive microwaves from communications satellites, which transmit data transmissions or broadcasts, such as satellite television, that communicate with them do not have to move to track them, but can be pointed permanently at the position in the sky where they stay.
A geostationary orbit is a particular type of geosynchronous orbit (sometimes abbreviated GSO), an orbit around the Earth with an orbital period of one sidereal day (approximately 23 hours 56 minutes and four seconds), matching the Earth’s sidereal rotation period.
