3 articles for "Nutation"
Nutation [Astro*Index]A small oscillation (plus or minus 9") in the spin-axis of the Earth, which is superimposed on the precessional circle. The principle trigonometric term in the nutation has a period of about 18.6 years.
See also:Nutation [Prima]
♦ Precession ♦ Ecliptic
A small periodic oscillation (plus or minus 20") of the rotational axis of the Earth around its "mean" position. Due to the nutation, the instantaneous pole of rotation of the Earth oscillates around a mean pole that advances by the precession around the pole of the ecliptic.
The main cycle for the nutation is 18.6 years.
See also:Nutation [Munkasey M.]
♦ Precession ♦ Ecliptic
The back and forth variations of the Earth's axis in itsprecession cycle. This is like a "wobble" movement, amounting to 9 seconds of arc in a 19 year cycle.
See also:
♦ Precession ♦ Ecliptic
Astro*Index Copyright © 1997 Michael Erlewine