Evection

Evection

Evection (Latin for "carrying away"), in astronomy, is the largest inequality produced by the action of the Sun in the monthly revolution of the Moon around the Earth.

Evection causes the Moon's ecliptic longitude to vary by approximately 1.27 degrees, with a period of about 31.8 days. It arises from a periodic variation of the eccentricity of the Moon's orbit and the position of its perigee, caused by the action of the Sun. Evection was known in ancient times, and its discovery is usually attributed to Hipparchus.

References

*Brown, E.W. "An Introductory Treatise on the Lunar Theory." Cambridge University Press, 1896 (republished by Dover, 1960).


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  • évection — [ evɛksjɔ̃ ] n. f. • XIVe; lat. evectio « action de s élever », rac. vehere ♦ Astron. Inégalité périodique dans le mouvement de la Lune, due à l attraction solaire. ● évection nom féminin (latin evectio, onis, action de s élever en l air)… …   Encyclopédie Universelle

  • Evection — E*vec tion [L. evectio a going up, fr. evehere to carry out; e out + vehere to carry: cf. F [ e]vection.] 1. The act of carrying up or away; exaltation. [Obs.] Bp. Pearson. [1913 Webster] 2. (Astron.) (a) An inequality of the moon s motion in its …   The Collaborative International Dictionary of English

  • Evectĭon — (v. lat.), 1) das Emporsteigen, Erbebung; 2) (Astron.), die große Störungsgleichung des Mondes, erzeugt durch die Sonne. Zur Zeit der Syzygien (s.d.) mischt sich die E. (die gleich dem Winkel von 1°16′ 20 bis 28″, multiplicirt mit dem Sinus der… …   Pierer's Universal-Lexikon

  • Evection — Evection, lat. deutsch, Erhebung; in der Astronomie die Ungleichheit der Mondsbahn, durch die Anziehung der Erde bewirkt …   Herders Conversations-Lexikon

  • evection — [ē vek′shən, ivek′shən] n. [L evectio, a going up, carrying out < evectus, pp. of evehere < e , out, from + vehere, to carry: see WAY] a periodical variation in the motion of the moon in its orbit, caused by the attraction of the sun… …   English World dictionary

  • evection — evectional, adj. /i vek sheuhn/, n. Astron. a periodic irregularity in the moon s motion, caused by the attraction of the sun. [1650 60; < L evection (s. of evectio) a going upwards, flight, equiv. to evect(us) (ptp. of evehere to carry forth,… …   Universalium

  • evection — noun Modification of the lunar orbit due to the gravitational effects of the Sun …   Wiktionary

  • évection — (é vè ksion) s. f. Terme d astronomie. Inégalité périodique que l on a observée dans le mouvement de la lune et qui est due à l attraction solaire. •   La seconde inégalité, appelée par quelques uns évaction, est proportionnelle au sinus du… …   Dictionnaire de la Langue Française d'Émile Littré

  • EVECTION — evectionem …   Abbreviations in Latin Inscriptions

  • evection — [ɪ vɛkʃ(ə)n] noun Astronomy regular variation in the eccentricity of the moon s orbit around the earth, caused mainly by the sun s attraction. Origin C17 (in the sense elevation, exaltation ): from L. evectio(n ), from evehere carry out or up …   English new terms dictionary

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