What does apolune mean?
Apolune is the technical term for the point in an orbit around the Moon at which the orbiting object is farthest from the Moon's centre — the lunar equivalent of the apogee in an Earth orbit. The word belongs to a family of precise orbital terms built on the Greek prefix 'apo-', meaning 'away from', combined with 'lune', from the Latin name for the Moon. Its natural counterpart is perilune, the closest point of the same orbit. Apolune is not part of general vocabulary; it surfaces almost entirely in aerospace contexts, appearing in mission plans, orbital calculations, and coverage of lunar spacecraft such as mapping probes and crewed vehicles. Engineers often care about apolune because manoeuvres performed there can efficiently reshape an orbit, raising or lowering the opposite side. For readers interested in spaceflight, knowing the term offers a small window into the exacting vocabulary with which scientists describe the geometry of journeys beyond Earth.
nounThe point in an orbit around the Moon that is farthest from the Moon's centre. It is the lunar counterpart of the apogee, the point of maximum distance in any orbit.
- The point in an orbit around the Moon at which the orbiting body is farthest from the Moon's centre.
"The spacecraft's fuel-efficient transfer began at apolune, where it fired its engines to raise the opposite side of its orbit."
"Mission controllers timed the burn for apolune, when the probe was at its greatest distance from the Moon."
"Because the satellite's orbit was highly elliptical, its apolune lay thousands of kilometres above the lunar farside."
The plural is rare, since a single orbit has only one apolune; it would arise only when discussing multiple orbits or multiple spacecraft.
"The two probes settled into orbits whose apolunes differed by several hundred kilometres."
Every spacecraft circling the Moon has two special moments each lap — and apolune is the one where it's drifting as far from the lunar surface as its orbit allows.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of apolune
Apolune derives from the Greek prefix 'apo-', meaning 'away from' or 'far from', joined to 'lune', from Latin 'luna', the Moon. It follows the same naming pattern as the older orbital terms apogee ('away from Earth') and aphelion ('away from the Sun'), which were formed from Greek roots during the development of classical astronomy. The term arose in the twentieth century, once spacecraft began orbiting bodies other than Earth and astronomers needed Moon-specific equivalents of these established words. It shares its prefix with related terms such as perigee and perihelion's antonymic counterpart perilune, all belonging to the vocabulary of orbital mechanics.
How apolune is actually used
Apolune is a technical term used almost exclusively in aerospace engineering, orbital mechanics, and space-science reporting. It is rare in everyday language and appears mainly in mission documentation and specialist journalism about lunar exploration.
Easily confused with apolune
Apogee is the farthest point of an orbit around Earth, whereas apolune is the farthest point of an orbit specifically around the Moon.
Perilune is the closest point of an orbit around the Moon, while apolune is the farthest.