[ ˌpɛrɪ'hi:lɪən ]
■ noun ( plural perihelia -lɪə ) Astronomy the point in the orbit of a planet, asteroid, or comet at which it is closest to the sun. The opposite of aphelion .
Origin
C17: alt. of mod. L. perihelium (by substitution of the Gk inflection -on ), from Gk peri- 'around' + hēlios 'sun'.