

nu⋅ta⋅tion
[noo-tey-shuh
n, nyoo-]
| 1. | an act or instance of nodding one's head, esp. involuntarily or spasmodically. |
| 2. | Botany. spontaneous movements of plant parts during growth. |
| 3. | Astronomy. the periodic oscillation observed in the precession of the earth's axis and the precession of the equinoxes. |
| 4. | Mechanics. the variation of the inclination of the axis of a gyroscope to the vertical. |
Based on the Random House Dictionary, © Random House, Inc. 2009.
Cite This Source
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Cite This Source
Nutation
Nu*ta"tion\, n. [L. nutatio a nodding, fr. nutare to nod: cf. F. nutation.]1. The act of nodding. So from the midmost the nutation spreads, Round and more round, o'er all the sea of heads. --Pope. 2. (Astron.) A very small libratory motion of the earth's axis, by which its inclination to the plane of the ecliptic is constantly varying by a small amount. 3. (Bot.) (a) The motion of a flower in following the apparent movement of the sun, from the east in the morning to the west in the evening. (b) Circumnutation.Cite This Source
nutation nu·ta·tion (n&oomacr;-tā'shən, ny&oomacr;-)
n.
The act of nodding the head, especially involuntarily.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
nutation (n -tā'shən) Pronunciation Key
|
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
nutation
in astronomy, a small irregularity in the precession of the equinoxes. 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 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 announced his discovery of nutation in 1748.
Learn more about nutation with a free trial on Britannica.com.
Cite This Source
Copyright © 2009, Dictionary.com, LLC. All rights reserved.
-tā'shən)