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.

Example Sentences

Recent Examples on the Web These are from aphelion and perihelion in 2005, but the scale is always about the same every year. —

Phil Plait, Discover Magazine, 5 July 2012 That means that at aphelion the center of the Earth was 152,092,424 km (94,505,851 miles) from the center of the Sun. —

Phil Plait, Discover Magazine, 5 July 2012 Perihelion -- closest approach -- happens in early January, and aphelion six months later. —

Phil Plait, Discover Magazine, 4 July 2011 Today though, aphelion occurs on or about 15:00 UT (11:00 Eastern US time), when the center of the Earth will be about 152,102,715 km (94,512,245 miles) from the center of the Sun -- give or take a few hundred meters. —

Phil Plait, Discover Magazine, 4 July 2011 On Independence Day, the Earth with reach its aphelion — its furthest point from the Sun — at 3:10 a.m. in Baltimore. —

Christine Condon, baltimoresun.com, 2 Jan. 2022 That moment, called aphelion, will occur when the distance between the two celestial bodies stretches to more than 94.5 million miles. —

NBC News, 5 Jan. 2022 Though perihelion occurs during winter in the Northern Hemisphere and aphelion occurs during summer, Earth's elliptical orbit around the sun does not cause the seasons. —

NBC News, 5 Jan. 2022 On Independence Day, the Earth will reach its aphelion — its furthest point from the Sun — at 3:10 a.m. in Baltimore. —

Christine Condon, baltimoresun.com, 2 Jan. 2022 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'aphelion.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.