Near-equatorial orbit

A near-equatorial orbit is an orbit that lies close to the equatorial plane of the primary body orbited. Such an orbit has an inclination near 0°. Such orbits lie near the primary's celestial equator, the great circle of the imaginary celestial sphere that is coplanar with the primary's equator. A geostationary orbit is a particular type of equatorial orbit, one which is geosynchronous. A satellite in a geostationary orbit appears stationary, always at the same point in the sky, to observers on the surface of the Earth.

Equatorial orbits can be advantageous for several reasons. For launches of human technology to space, sites near the Equator, such as the Guiana Space Centre in Kourou, French Guiana, or Alcantara Launch Centre in Brazil, can be good locations for spaceports as they provide some additional orbital speed to the launch vehicle by imparting the rotational speed of the Earth, 460 m/s, to the spacecraft at launch. The added velocity reduces the fuel needed to launch spacecraft to orbit. Since Earth rotates eastward, only launches eastward take advantage of this boost of speed. Westward launches, in fact, are especially difficult from the Equator because of the need to counteract the extra rotational speed.

Equatorial orbits offer other advantages, such as to communication: a spaceship in an equatorial orbit passes directly over an equatorial spaceport on every rotation, in contrast to the varying ground track of an inclined orbit.