| n. | 1. | (Astron.) That point of a planet's or comet's orbit which is most distant from the sun, the opposite point being the perihelion. |
| Noun | 1. | aphelion - apoapsis in solar orbit; the point in the orbit of a planet or comet that is at the greatest distance from the sun Antonyms: perihelion - periapsis in solar orbit; the point in the orbit of a planet or comet where it is nearest to the sun |