That point in the orbit of a double star where the smaller star is farthest from its primary.

For an orbit around a star, the farthest point from that star.

means the greatest separation of the principals (q. v.) in a binary. It is a homologue of apogee for an Earth satellite, and aphelion for a planet. The term apocentron is used elsewhere in place of apastron to describe the farthest point on an orbit.

In an orbit around a star, the furthest point from the star.

The position in an orbit about a star at which the orbiting object is at its greatest distance from the star.

The point of greatest separation between two stars that are in orbit around each other. The opposite of periastron.

The point of greatest separation of two stars in a binary star system.