Bearing (navigation)

In navigation, a bearing is the angle between the direction to an object and a reference direction. Unless otherwise specified, the reference direction is generally understood to be magnetic North, in which case the term compass bearing is also used. If navigating by gyrocompass, the reference direction is true north. In stellar navigation[?], the reference direction is that of the North Star, Polaris.

Generalising this to two angular dimensions, a bearing is the combination of antenna azimuth and elevation required to point (aim) an antenna at a spacecraft. The bearing for geostationary satellites is constant. The bearing for polar-orbiting satellites varies continuously.