The motion of the celestial ephemeris pole with respect to the spatial frame is called nutation (including precession),and that with respect to the terrestrial frame is called polar motion.

• 通过引进章动坐标系相对惯性参照系的转动角速度随时间的变化,导出了一个可同时解出章动和极移的地球自转方程,用这个方程可同时研究地球的强迫和自由转动。