Definition of perihelion
noun (plural perihelia /-ˈhēlyə, -ˈhēlēə/ or perihelions)Astronomy
- the point in the orbit of a planet, asteroid, or comet at which it is closest to the sun. The opposite of aphelion.
mid 17th century: alteration of modern Latin perihelium (by substitution of the Greek ending -on), from Greek peri- 'around' + hēlios 'sun'