Definitions

1. adjective

of or relating to the period of a planet’s orbit nearest to the sun

“The perihelial passage of Mercury is a fascinating astronomical phenomenon.”

2. adjective

of or relating to the period of a planet’s orbit farthest from the sun

“The aphelional and perihelial periods of Earth’s orbit are crucial in understanding its climate patterns.”

3. noun

a point in a planet’s orbit that is closest to the sun

“The perihelion of the planet will occur in early spring, making it an ideal time for astronomical observations.”