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aphelion

[ uh-fee-lee-uhn, uh-feel-yuhn, ap-hee-lee-uhn ]
/ əˈfi li ən, əˈfil yən, æpˈhi li ən /
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noun, plural a·phe·li·a [uh-fee-lee-uh, uh-feel-yuh, ap-hee-lee-uh]. /əˈfi li ə, əˈfil yə, æpˈhi li ə/.

Astronomy. the point in the orbit of a planet or a comet at which it is farthest from the sun.

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Compare perihelion.

Origin of aphelion

1650–60; Hellenized form of New Latin aphēlium<Greek *aphḗlion (diástēma) off-sun (distance), neuter of *aphḗlios (adj.), equivalent to ap-ap-2 + hḗli(os) sun + -os adj. suffix. See apogee
a·phe·li·an, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for aphelion

aphelion
/ (æpˈhiːlɪən, əˈfiː-) /

noun plural -lia (-lɪə)

the point in its orbit when a planet or comet is at its greatest distance from the sunCompare perihelion
aphelian, adjective
C17: from New Latin aphēlium (with pseudo-Greek ending -ion) from ap- + Greek hēlios sun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for aphelion

aphelion
[ ə-fēlē-ən ]

The point at which an orbiting body, such as a planet or comet, is farthest away from the Sun. Compare apogee perihelion.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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