noun
perihelion distance
Technical term in astronomy; the distance between a celestial body and the Sun at its closest approach.
この彗星の近日点距離は約0.5天文単位です。
The perihelion distance of this comet is about 0.5 astronomical units.
Aphelion distance; the farthest point from the Sun, opposite of 近日点距離.
Compound of 近日点 (perihelion) and 距離 (distance).