perihelion
Pronunciation: /ˌpɛrɪˈhiːlɪən/
Definition of perihelion
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 perihelionThe opposite of aphelion.
Origin:
mid 17th century: alteration of modern Latin perihelium (by substitution of the Greek inflection -on), from Greek peri- 'around' + hēlios 'sun'