Definitions

1. noun

The point at which the orbit of a celestial body is closest to the sun, particularly the point in the orbit of the Earth that is closest to the sun.

“The perihelion of Mars occurs in mid-January of each year.”

2. noun

The point at which the orbit of a celestial body is farthest from the sun, particularly the point in the orbit of the Earth that is farthest from the sun.

“The aphelion of Mars occurs in late July of each year.”