Earth & SkyGreek → English
Aphelion
/əˈfiːliən/noun
The point in an orbit farthest from the sun.
The Greek roots
ἀπό
apó
away from
ἥλιος
hḗlios
sun
Literally: “away from the sun”
The story of the word
Kepler needed the term once orbits became ellipses with the sun at a focus, and he built the Latin aphelium on the model of the older apogee. English has had aphelion since the 1650s. The counterintuitive part is the calendar: the earth reaches aphelion in early July, about 152 million kilometres out, so the northern summer happens when we are furthest away. Axial tilt, not distance, makes the seasons.
- How it travelled
- Ancient Greek → Modern Latin → English
- First recorded
- 1650s
Same family
perihelionheliocentricheliumheliotrope
In a sentence
The comet takes ninety years to crawl from perihelion back out to aphelion.