noun (plural perihelia /-lɪə/)Astronomy
The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun: today Mercury is at perihelion The opposite of aphelion.
More example sentences
- He calculated to within a month the return in 1759 of Halley's comet to its perihelion (closest point to the Sun).
- For objects orbiting Earth, periapsis and apoapsis are known as perigee and apogee; for objects orbiting the Sun, these locations are known as perihelion and aphelion.
- 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.
mid 17th century: alteration of modern Latin perihelium (by substitution of the Greek inflection -on), from Greek peri- 'around' + hēlios 'sun'.
More definitions of perihelionDefinition of perihelion in:
- The US English dictionary