aphelion

noun

aph·elion a-ˈfēl-yən

ˌap-ˈhēl-

plural aphelia a-ˈfēl-yə

ˌap-ˈhēl-

: the point farthest from the sun in the path of an orbiting celestial body (such as a planet) compare perihelion

Did you know?

Aphelion and perihelion are troublesome terms. Which one means a planet is nearest to the sun and which means it is farthest away? An etymology lesson may help you keep those words straight. Just remember that the "ap" of aphelion derives from a Latin prefix that means "away from" (the mnemonic "'A' for 'away'" can help too); peri-, on the other hand, means "near." And how are aphelion and perihelion related to the similar-looking astronomical pair apogee and perigee? Etymology explains again. The "helion" of aphelion and perihelion is based on the Greek word hēlios, meaning "sun," while the "gee" of apogee and perigee is based on gaia, meaning "earth." The first pair describes distance in relation to the sun, the second in relation to the Earth.

Examples of aphelion in a Sentence

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Such a circumstance will happen in 2027: On March 4 of that year, Mars will be at aphelion, its farthest point from the sun. —

Joe Rao, Space.com, 10 Jan. 2025 July 3: Earth will be at aphelion, the farthest point in its orbit from the sun. —

Phil Plait, Scientific American, 9 Jan. 2025 Earth’s Elliptical Orbit Earth’s elliptical orbit causes slight variations in solar energy, with about 7% more sunlight reaching Earth during perihelion than aphelion. —

Jamie Carter, Forbes, 4 Jan. 2025 Mars’s orbit is much more elliptical—with an aphelion, or furthest remove from the sun, of 155 million miles and a perihelion, or closest approach, of 128 million miles. —

Jeffrey Kluger, TIME, 6 Sep. 2024 See all Example Sentences for aphelion