On free nutation of the rotation of a rigid body.
Abstract
This paper proves that the free nutational motion of the vector of instantaneous rotation of a perfectly rigid body can never be exactly elliptical. The motion is shown to be ideally circular in cases where the modulus of the elliptical function, ksquared, is exactly zero. In the case of earth it is found that the modulus ksquared is negligibly small and that the flattening of the corresponding ellipse is also small, to the extent that the 'ellipticity' of the free nutational motion of earth's instantaneous rotation vector cannot be detected by modern astrometric means.
 Publication:

Studia Geophysica et Geodaetica
 Pub Date:
 September 1979
 DOI:
 10.1007/BF01633911
 Bibcode:
 1979StGG...23..205B
 Keywords:

 Body Kinematics;
 Nutation;
 Rotating Bodies;
 Space Mechanics;
 Ellipticity;
 Euler Equations Of Motion;
 Vector Analysis;
 Astronomy;
 Celestial Bodies:Nutation