nutation

/noo-tey-shuhn, nyoo-/US // nuˈteɪ ʃən, nyu- //UK // (njuːˈteɪʃən) //

营养,螺母,营养学,营养品

Definitions

n.名词 noun

1
- : an act or instance of nodding one's head, especially involuntarily or spasmodically.
- : Botany. spontaneous movements of plant parts during growth.
- : Astronomy. the periodic oscillation observed in the precession of the earth's axis and the precession of the equinoxes.
- : Mechanics. the variation of the inclination of the axis of a gyroscope to the vertical.

Why did he not continue in the same spot, except for the slow change caused by the nutation or nodding of Venus?
It is affected by the motions of Precession and Nutation, of which the former has been known since the time of Hipparchus.
These two motions are defined with greater detail in the articles Precession of the Equinoxes and Nutation.
Many growing stems have also a movement of Nutation, that is, of nodding successively in different directions.
In the case of nutation the North Pole remains in the same geographical position, but points to a different part of the heavens.