perihelion

A diagram illustrating a planet at aphelion (position 1) and perihelion (position 2) from the Sun (3).

From perihelium (“perihelion”) (obsolete) +‎ -on (suffix forming nouns) (from Ancient Greek -ον (-on)). Perihelium is borrowed from Late Latin perihelium, from Ancient Greek περί- (perí-) (a variant of περι- (peri-, prefix meaning ‘around; surrounding’), ultimately from Proto-Indo-European *per- (“before, in front; first”)) + ἥλιος (hḗlios, “sun”) (ultimately from Proto-Indo-European *sóh₂wl̥ (“sun”) or a pre-Hellenic language), which was modelled after perigeum (“point in an orbit about the Earth that is closest to the Earth, perigee”).[1]

• (Received Pronunciation) enPR: pĕr'ĭ-hēʼlĭ-ən, IPA^(key): /ˌpɛɹ.ɪˈhiː.lɪ.ən/

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• (General American) enPR: pĕr'ə-hēʼlē-ən, pĕr'ə-hēlʼyən; IPA^(key): /ˌpɛɹ.əˈhiː.li.ən/, /ˌpɛɹ.əˈhil.jən/
• Rhymes: -ɪljən (GA)
• Hyphenation: pe‧ri‧he‧li‧on

perihelion (plural perihelia or (deprecated) perihelions)

1. (astronomy) The point in the elliptical orbit of a comet, planet, etc., where it is nearest to the Sun.

   Synonym: (symbol) ϖ

   Antonym: aphelion

   • 1656, Vincent Wing, “Of the Annuall Motion of the Earth”, in Astronomia Instaurata: Or, A New and Compendius Restauration of Astronomie. […], London: […] R. and W. Leybourn, for the Company of Stationers, →OCLC, part 1, paragraph 12, page 46:

     The æquation of the Earth encreaſeth from her Aphelion, until ſhe come to the point where it's greateſt, and from thence it again decreaſeth till ſhe come to her Perihelion, or oppoſite Auge: in like manner it increaſeth from her Perihelion to the point where it's greateſt, and afterwards decreaſeth till ſhe come againe to the Auge or Aphelion, [...]

   • 1693 April 4, J. de la Crose [i.e., Jean Cornand de Lacroze], “Letter XIII. To the Honourable Sir Edwin Sadler.”, in Memoirs for the Ingenious. Containing Several Curious Observations in Philosophy, Mathematicks, Physick, Philology, and Other Arts and Sciences. In Miscellaneous Letters. […], volume I, London: […] H. Rhodes […]; and for J. Harris […], →OCLC, page 98:

     They [the best astronomers of this age] all agree that the Planets turn in ſo many Ellipſes, of which the Sun is the focus; the reaſon of it is, that they are obſerved to be in ſome points called Perihelia, nearer to the Sun, and, in the oppoſite points call'd Aphelia, farther from it; which could not be, if they mov'd in a perfect circle.

   • 1734, J[ohn] Keill, “A Defence of the Remarks Made on Mr Whiston’s New Theory”, in An Examination of Dr. Burnet’s Theory of the Earth: With Some Remarks on Mr. Whiston’s New Theory of the Earth. […], 2nd edition, London: […] H. Clements, […]; and S. Harding, […], →OCLC, page 319:

     [I]f Comets were obſerv'd to have to Atmoſphere after their return from the Regions beyond Saturn, before they arrived at their Perihelia again, then indeed this reaſoning were unavoidable; but ſeeing the contrary is evident from Aſtronomical Obſervations, it cannot affect his [William Whiston's] Hypotheſis.

   • 1893–1894, “Astronomy, Astronomical Symbols, Elements of the Solar System, and Theories Regarding the Planets, According to the Latest and Best Authorities”, in The Statistician and Economist, 17th edition, San Francisco, Calif., New York, N.Y.: L. P. McCarty, published 1893, →OCLC, part IV (The Miscellany), page 575:

     The base of the system is that all planets, comets and satellites go through a reversed change of motion, volume, distance and density at their perihelions and aphelions, each orbital revolution: this being effected through reciprocating electric currents or lines that exist and undulate between the planetary bodies, with which currents are used to carry on these planetary changes. These changes continue from perihelion to aphelion, and from aphelion to perihelion again, and are in proportion to the amount of ellipticity in their orbits—the greater the ellipticity the greater the changes.

   • 1965 November 6, G[iuseppe] Colombo, “Rotational Period of the Planet Mercury [letter]”, in Nature: A Weekly Illustrated Journal of Science, volume 208, number 5010, London: Macmillan and Co.; New York, N.Y.: The Macmillan Company, →DOI, →OCLC, page 575, column 1:

     This rotational motion could have the axis of minimum moments of inertia nearly aligned with the Sun–Mercury radius vector at every perihelion passage.

   • 2003, Malcolm S[im] Longair, “An Introduction to General Relativity”, in Theoretical Concepts in Physics: An Alternative View of Theoretical Reasoning in Physics, 2nd edition, Cambridge, Cambridge: Cambridge University Press, →ISBN, section 17.7 (Advance of Perihelia of Planetary Orbits), page 464:

     In this case, the rate of advance of the perihelia of their elliptical orbits provides important information about the masses of the neutron stars as well as providing very sensitive tests of general relativity itself.

   • 2011, Peter Duffett-Smith, Jonathan Zwart, “The Planets, Comets and Binary Stars”, in Practical Astronomy with Your Calculator or Spreadsheet, 4th edition, Cambridge, Cambridgeshire: Cambridge University Press, →ISBN, section 61 (Comets), page 143:

     The longitude of the comet is not usually specified at a particular epoch. Rather, the epoch is given when the comet is at perihelion, the point of its closest approach to the Sun. [...] Note that, as in the case of the planetary elements, we have specified ϖ, the longitude of the perihelion.

2. (figurative) The highest point or state; the peak, zenith.

   Synonyms: see Thesaurus:apex

   • 1881 July, “Pot-pourri”, in Potter’s American Monthly: An Illustrated Magazine of History, Literature, Science and Art, volume XVII, number 115, Philadelphia, Pa.: John E. Potter & Company, […], →OCLC, page 95, column 1:

     [T]he magnificence of his compliment had quite shaken the general's [Ulysses S. Grant's] modesty, and that he could only say that France must come to the perihelion of her glory under such rulers as Grevy [i.e., Jules Grévy].

   • 1909 January, T[homas] Nelson Downs, “Card-tricks Involving Sleight of Hand”, in John Northern Hilliard, editor, The Art of Magic, Buffalo, N.Y.: The Downs-Edwards Company, →OCLC, page 44:

     This brilliant trick was the invention of the late Dr. Hofzinzer, of Vienna, who, at the perihelion of his fame, was regarded as the greatest card conjurer in the world.

   • 2015, Jonathan Lethem, “Track-by-track [Jonathan Lethem on Talking Heads: What was the Fate of the Fear of Music Songs in Live Performance?]”, in Mark Woodworth, Ally-Jane Grossan, editors, How to Write about Music: Excerpts from the 33⅓ Series, Magazines, Books and Blogs with Advice from Industry-leading Writers, New York, N.Y., London: Bloomsbury Academic, Bloomsbury Publishing, →ISBN, page 86:

     At that concert, undergoing a state of rapture that easily rekindles in memory, the boy turned to his best friend Joel and gave the simplest and most unguarded expression possible to a feeling nearly anyone has had at least once (I hope), perhaps most often at the perihelion of some sexual experience, or drug experience. I don't remember the exact words the boy used, but the gist was, "We must never, ever, miss a chance to do this again."

• periapsis

• perihelial (rare)
• perihelian (archaic)
• perihelic

• Appendix:List of astronomical terms

• apsis on Wikipedia.Wikipedia

perihelion

1. accusative singular of perihelio

Borrowed from English perihelion, from English perihelium + -on (“noun suffix”), the former from Late Latin perihelium, from Ancient Greek περι- (peri-, “around, surrounding”) + ἥλῐος (hḗlios, “the sun”), the latter from -ον (-on, “noun suffix”).

• IPA^(key): /ˌpɛrɪˈhɛljɔn/

perihelion m (plural perihelionau or perihelia)

1. (astronomy) perihelion

   Antonym: affelion

• R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “perihelion”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies