Apoapsis

Part of speech: noun

Definitions

1. The furthest point in the trajectory of an orbiting body relative to the mass it orbits describes the angle at which gravitational influence is least strong
2. It represents the apex of an elliptical orbit where the celestial object is maximally distanced from the focal mass of attraction
3. The point in an orbit where the orbiting object is at its greatest distance from the body it revolves around

Etymology: Astronomers needed a precise term for the far end of an orbit, and they built it from two Greek pieces: "apó", meaning "away from" or "off", and "apsis", a word for an arch or vault. The apsis of an orbit is the point where the path comes closest to, or farthest from, the body being orbited, so the prefix tells you which end is meant. Apoapsis is the far point, and its counterpart, periapsis, is the near point. The prefix "apo-" reached English through Greek combining forms, so the word is a compound of classical elements assembled by modern astronomers rather than an ancient term. Its use in English is part of the technical vocabulary of celestial mechanics, where the two-part system of apsides is standard.

Synonyms: aphelion, apogee