1. In general, the variation with time of the Eulerian angle that measures the angle between the rotation axis of a spinning rigid body and a constant vertical direction. 2. In astronomy specifically, the irregular oscillation in the precessional motion of the earth's rotation axis, caused primarily by lunar perturbations. It has a principal period of 18.6 yr and moves the equinox as much as 17" ahead of, or behind, its mean position.
It is that part of the precessional motion of the pole of Earth's equator which depends upon the periodic motion of Sun and Moon in their orbit round Earth. The periodic oscillation observed in the precession of Earth's axis and the precession of the equinoxes. It is periodic in nature equal to a 19-year cycle.» Compatibility Report A synastry analysis into personal relationships with your friend, lover, companion, partner. The compatibility chart gives you the verdic of your love.
the short-period oscillations in the motion of the pole of rotation of a freely rotating body that is undergoing torque from external gravitational forces. Nutation of the Earth's pole is discussed in terms of components in obliquity and longitude (see longitude, celestial.)
motion of the terrestrial rotation axis. It is due to the fact that the gravitational attraction of the Moon and the Sun on the terrestrial equatorial bulge varies in time according to their relative positions. Due to the joint effect of nutation and of another perturbations of greater amplitude (precession), the terrestrial rotation axis has a tortuous motion in the sky, instead of maintaining a fixed direction in space.
1. The oscillation of the axis of any rotating body, as a gyroscope rotor. 2. Specifically, in astronomy, irregularities in the precessional motion of the equinoxes because of varying positions of the moon and, to a lesser extent, of other celestial bodies with respect to the ecliptic. Because of nutation, the earth's axis nods like a top, describing a slightly wavy circle about the ecliptic pole. The maximum displacement is about 9.21 seconds (constant of nutation) and the period of a complete cycle is 18.60 tropical years (period of moon's node, nutation period).