An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 2 Search : nutation
nutation
  کلتاو   
kaltâv

Fr.: nutation   

Mechanics: A wobbling motion of a spinning rigid body, such as a top, as it precesses about its vertical axis.
Astro.: A slight nodding motion of the Earth's axis of rotation, which has a principal period of 18.6 years. It is primarily caused by lunar perturbations, and is superimposed on the precession of the equinoxes and moves the equinox as much as 17'' ahead of or behind its mean position.

Fromm L. nutation-, from nutat(us), p.p. of nutare "to wobble, to sway, to nod repeatedly," from nu "nod" + -ta frequentative suffix + -tus p.p. ending + -ion a suffix denoting action or condition.

Kaltâv, from Kermâni keletow, Malâyeri kallatow "wobbling," from kal, kalleh "head" + tâv, tow, tâb "swing, twist," from tâbidan "to twist, to spin."

nutation in right ascension
  کلتاو ِ راست‌افراز   
kaltâv-e râst-afrâz

Fr.: nutation en ascension droite   

Same as → equation of the equinoxes.

nutation; → right ascension.