# nutation

nutation
/nooh tay"sheuhn, nyooh-/, n.
1. an act or instance of nodding one's head, esp. involuntarily or spasmodically.
2. Bot. spontaneous movements of plant parts during growth.
3. Astron. the periodic oscillation observed in the precession of the earth's axis and the precession of the equinoxes.
4. Mech. the variation of the inclination of the axis of a gyroscope to the vertical.
[1605-15; < L nutation- (s. of nutatio), equiv. to nutat(us) (ptp. of nutare to nod repeatedly; nu- nod + -ta- freq. suffix + -tus ptp. ending) + -ion- -ION; cf. NUMEN]

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in astronomy, a small irregularity in the precession of the equinoxes (equinoxes, precession of the). Precession is the slow, toplike wobbling of the spinning Earth, with a period of about 26,000 years. Nutation (Latin nutare, “to nod”) superimposes a small oscillation, with a period of 18.6 years and an amplitude of 9.2 seconds of arc, upon this great slow movement. The cause of nutation lies chiefly in the fact that the plane of the Moon's (Moon) orbit around the Earth is tilted by about 5° from the plane of the Earth's orbit around the Sun. The Moon's orbital plane precesses around the Earth's in 18.6 years, and the effect of the Moon on the precession of the equinoxes varies with this same period. The British astronomer James Bradley (Bradley, James) announced his discovery of nutation in 1748.

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Universalium. 2010.

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• nutation — [ nytasjɔ̃ ] n. f. • 1748; lat. nutatio, onis ♦ Didact. 1 ♦ Astron. Oscillation périodique de l axe de rotation de la Terre (axe du monde) autour de sa position moyenne. Par ext. Nutation de l axe d un astre. ♢ Math. Angle de nutation, formé par… …   Encyclopédie Universelle

• Nutation — Nutation, das Schwanken der Erdachse, eine in der Periode von etwa 18,6 Jahren verlaufende periodische Richtungsveränderung der Drehungsachse der Erde mit beträchtlicher Amplitude (nicht zu verwechseln also mit der kleinen, seit einigen Jahren… …   Lexikon der gesamten Technik

• Nutation — Nu*ta tion, n. [L. nutatio a nodding, fr. nutare to nod: cf. F. nutation.] 1. The act of nodding. [1913 Webster] So from the midmost the nutation spreads, Round and more round, o er all the sea of heads. Pope. [1913 Webster] 2. (Astron.) A very… …   The Collaborative International Dictionary of English

• Nutation — (v. lat.), 1) Neigung; N. der Erdachse, s.u. Erde I. B) a); 2) einseitiges Hinken …   Pierer's Universal-Lexikon

• Nutation — (lat.), das von Bradley 1747 entdeckte »Schwanken« der Erdachse um eine mittlere Lage, gleich der Präzession (s. d.) eine Folge der Anziehung von Sonne und Mond auf die abgeplattete Erde. Vermöge der Präzession beschreibt der mittlere Pol des… …   Meyers Großes Konversations-Lexikon

• Nutation — Nutatiōn (lat.), Schwanken der Erdachse, die periodische Veränderung in der Richtung der Erdachse, hervorgerufen durch die veränderte Anziehungskraft des Mondes auf die abgeplattete Erdkugel zufolge der Bewegung der Mondknoten. Die verlängerte… …   Kleines Konversations-Lexikon

• Nutation — Nutation, lat. dtsch., das Schwanken; das Schwanken der Erdachse, s. Schwanken …   Herders Conversations-Lexikon

• Nutation — er betegnelsen for en retningsændring af jordaksen fremkaldt af Månen …   Danske encyklopædi

• nutation — (n.) 1610s, action of nodding, from L. nutationem (nom. nutatio), noun of action from pp. stem of nutare to nod, from PIE *neu to nod (see NUMINOUS (Cf. numinous)). Astronomical use is from 1715. Related: Nutational …   Etymology dictionary

• nutation — [no͞o tā′shən, nyo͞otā′shən] n. [L nutatio < nutare, to nod: see NUTANT] 1. the act or instance of nodding the head 2. a periodic variation in the inclination from the vertical of the rotation axis of a spinning body, as a top 3. Astron. such… …   English World dictionary

• Nutation — See also: Nutation in plants Rotation (green), Precession (blue) and Nutation in obliquity (red) of the Earth Nutation (from Latin: nūtāre, to nod) is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric… …   Wikipedia