The Theory of the Earth's Orientation, with Some New Results for Nutation

The rotation of the earth is variable at a number of time scales, from a few days to thousands of years and longer. Variations occur in the rotation rate, in the geographical position of the rotation axis (referred to as polar motion), and in the position of the axis relative to inertial space (referred to as nutation and precession). The interpretations of the various observations have implications for the dynamical behavior and structure of the earth's deep interior, and for various aspects of meteorology and oceanography. These are reviewed below. Also included is an Appendix describing a model of the diurnal resonance in nutation for a non-hydrostatically pre-stressed earth.