aphelion
/æpˈhil.jən/
UK: /æpˈhiː.lɪ.ən/
ÆPHIL · jən (2 syllables)
English
Noun
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Definition
The point in the elliptical orbit of a comet, planet, or other astronomical object, where it is farthest from the Sun.
Etymology
From New Latin aphēlium (whence English aphelium, now displaced) + -ion (used in the names of other apsides). Aphelium was formed from Ancient Greek ἀπο- (apo-, prefix meaning ‘away, from, off’) + ἥλῐος (hḗlĭos, “the sun”) (ultimately from Proto-Indo-European *sóh₂wl̥ (“the sun”)), modelled after New Latin apogaeum (“apogee”). The plural form aphelia is from aphelion + -a (plural form of the suffix -on).
Example Sentences
- "[I]t follows from the theory of gravity, that the aphelia of Mercury, Venus, the Earth, and Mars, slightly progress."
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