Motion of the Earth's Poles

Motion of the Earth’s Poles 

the displacement of the geographic poles of the earth on its surface. This motion occurs because the instantaneous axis of the earth’s rotation at a given moment does not maintain a fixed direction in the body of the earth.

I. Newton first pointed to the possibility of the motion of the earth’s poles as a feature of the earth’s rotation in 1687. The mathematical theory for this phenomenon was developed by L. Euler in 1790. A century later actual changes were found in the latitudes of points on the earth’s surface caused by the motion of the earth’s poles, and the possibility was demonstrated of studying the shift of the earth’s poles by repeatedly determining the latitudes of several points. Data on the motion of the poles are of importance in astronomy and geodesy since they cause constant changes in the coordinates of points on the earth’s surface and in the azimuths of terrestrial objects. These changes affect the results of astronomical and geodetic measurements.