noun (plural aphelia /-lɪə/)Astronomy
The point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun: Mars is at aphelion The opposite of perihelion.
More example sentences
- This affects the climate because the influx of solar energy to our planet would then vary between perihelion and aphelion by a larger proportion than at present.
- This is because at aphelion the planet is moving slowest, and consequently it is less likely to pass across the Sun during the critical window.
- There are small cyclic variations in those apparent sizes because the Earth-Moon distance changes as the latter moves between perigee and apogee, and the Earth-Sun separation alters as the former moves between perihelion and aphelion.
mid 17th century: alteration of modern Latin aphelium (by substitution of the Greek inflection -on), from Greek aph' hēlion 'from the sun'.
More definitions of aphelionDefinition of aphelion in:
- The US English dictionary