Earth & SkyGreek → English
Perihelion
/ˌpɛrɪˈhiːliən/noun
The point in an orbit where a body comes closest to the sun.
The Greek roots
περί
perí
around, near
ἥλιος
hḗlios
sun
Literally: “near the sun”
The story of the word
Kepler coined the Latin perihelium while working out that orbits are ellipses, which puts the sun at a focus rather than the centre and makes a planet's distance change through the year. English has used perihelion since the seventeenth century. Its opposite is aphelion, ἀπό plus the same sun, and the earth reaches it in early July, which surprises most northern hemisphere readers.
- How it travelled
- Ancient Greek → Modern Latin → English
- First recorded
- 17th century
Same family
aphelionheliocentricheliumheliotrope
In a sentence
The comet brightened sharply as it approached perihelion.