Remarks about External Forces Acting on Earth’s Rotation Axis

Abstract

It is well known that a variation in the direction of Earth’s rotation axis is a real astronomical phenomenon , named nutation . It is interesting if a variation of this axis can take place only in intensity, in the simplest theoretical case of only two rigid body dynamic s . This paper presents two positions of the Moon during its monthly orbit, where a sudden variation of Earth ’ s rotation axis in intensity can take place. The duration of this phenomenon is limited in time , maybe an instant or a day, and then a vortex can appear.