ScienceJuly 31, 2026

perihelion

pehr-uh-HEE-lee-uhn

Definition

The point in the orbit of a planet, asteroid, or comet where it is closest to the Sun.

Etymology

The word is derived from the Greek 'peri' (meaning around or near) and 'helios' (meaning Sun). It entered English in the 17th century to describe the orbital mechanics of bodies in our solar system.

In the news

In this article, the word is used to describe the point in the Parker Solar Probe's orbit where it reaches its maximum speed as it makes its closest approach to the Sun. It is a critical location for the probe's mission objectives.

What's the Fastest Thing in the Universe?

Read the full article ↗

WorldAtlas

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