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aphelion

[uh-fee-lee-uh n, uh-feel-yuh n, ap-hee-lee-uh n] /əˈfi li ən, əˈfil yən, æpˈhi li ən/
noun, plural aphelia
[uh-fee-lee-uh, uh-feel-yuh, ap-hee-lee-uh] /əˈfi li ə, əˈfil yə, æpˈhi li ə/ (Show IPA)
1.
Astronomy. the point in the orbit of a planet or a comet at which it is farthest from the sun.
Compare perihelion.
Origin
1650-1660
1650-60; Hellenized form of Neo-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
Related forms
aphelian, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples for aphelion
  • What it says is that the neighborhood is what goes from perihelion to aphelion.
  • The presence of these was originally inferred by looking at the aphelion of short and long period comets respectively.
British Dictionary definitions for aphelion

aphelion

/æpˈhiːlɪən; əˈfiː-/
noun (pl) -lia (-lɪə)
1.
the point in its orbit when a planet or comet is at its greatest distance from the sun Compare perihelion
Derived Forms
aphelian, adjective
Word Origin
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
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Word Origin and History for aphelion
n.

"point farthest from the sun" (of a celestial body's orbit), 1670s, a Grecianized form of Modern Latin aphelium, altered by Johannes Kepler based on Greek apo heliou "away from the sun," from apo "away from" (see apo-) + heliou, genitive of helios "sun" (see sol). The whole was formed on the model of Ptolemaic apogaeum (see apogee) to reflect the new helio-centric model of the universe.

Online Etymology Dictionary, © 2010 Douglas Harper
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aphelion in Science
aphelion
  (ə-fē'lē-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 © 2002. Published by Houghton Mifflin. All rights reserved.
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