Diagram of a body's direct orbit around the Sun, with its nearest (perihelion) and farthest (aphelion) points. Source: https://en.wikipedia.org/wiki/Apsis#/media/File:Perihelion-Aphelion.svg
Short Definition:
Perihelion is the farthest point in the orbit of a planetary body about the Sun. This point is present in every Solar System orbiting body orbit due to the fact all orbits are elliptical.
Detailed Definition:
Perihelion is the farthest point in the orbit of a planetary body about the Sun in the Solar System. In case of describing generic star orbiting system, such point is called an apsis as the farthest point in the orbit of a planetary body about its primary body. For bodies moving around the Sun in a stable elliptical orbit, the perihelion is crossed at regular intervals, every orbital period. At perihelion, the Earth is 147.1 million km (0.9833 au) from the Sun. This usually takes place between 2nd and 4th January and occurs at a slightly different time each year due to interference from other celestial bodies.
Etymology:
From Proto-Indo-European *per- (“before, in front; first”) + ἥλιος (hḗlios, “sun”) + -on (suffix forming nouns) (from Ancient Greek -ον (-on))
Sample Sentence(s):
"If the comet's perihelion (its closest point to the sun) coincides with the shower's peak, a rare meteor storm can occur, creating thousands of meteor showers per hour."
- Skyler Caruso, Peoplemag, 4 Oct. 2022
"Earth makes its closest past on Jan. 4, which is called perihelion."
