ETYM Latin orbita a track or rut made by a wheel, course, circuit, from orbis a circle: cf. French orbite. Related to Orb.
Path of one body in space around another, such as the orbit of Earth around the Sun, or the Moon around Earth. When the two bodies are similar in mass, as in a binary star, both bodies move around their common center of mass. The movement of objects in orbit follows Johann Kepler's laws, which apply to artificial satellites as well as to natural bodies.
As stated by the laws, the orbit of one body around another is an ellipse. The ellipse can be highly elongated, as are comet orbits around the Sun, or it may be almost circular, as are those of some planets. The closest point of a planet’s orbit to the Sun is called perihelion; the most distant point is aphelion. (For a body orbiting the Earth, the closest and furthest points of the orbit are called perigee and apogee.).
The (usually elliptical) path described by one celestial body in its revolution about another.
To move in an orbit, as of celestial bodies:; SYN. revolve.