The gravitational interaction of the Earth and Moon produces a number of effects. The most obvious of these is the orbital motion of the Moon around the Earth, but there is also a motion of the Earth around the center of mass of the Earth-Moon system (discussed in Gravitational Interactions of the Earth and Moon: Barycentric Motion), tidal effects on the Earth and Moon (to be discussed in Gravitational Interactions of the Earth and Moon: Tides), and precessional effects on the Earth's axis of rotation (to be discussed here).

Consider the motions of the Earth:
(1) Orbital motion (around the Sun, once a year) --> seasonal stars, & rotation vs day

(2) Rotation around our axis --> day/night
(because of our tilt) --> seasons
The seasons depend upon the 23.5 degrees (approximately) tilt

(3) Precession = change in the direction of the axis, but without any change in the tilt
This changes the stars near (or not near) the Pole
But it does NOT affect the seasons (as long as the angle of 23.5 degrees stays the same)

(4) Also a wobbling around the precessional axis --> nutation
This is a change in the angle (small, about 1/2 degree one way or the other)
This occurs over an 18 year period and is due to the MOON exclusively
This would very slightly increase or decrease the amount of seasonal effects

(merely a placeholder, at the moment)
The phenomenon of precession will be discussed in general terms on another page. This page will provide an introductory mathematical foundation for the discussion, for the benefit of those interested in such a foundation.