Page "Rotation" Paragraph 13

Another consequence of the rotation of a planet is the phenomenon of precession.

Like a gyroscope, the overall effect is a slight " wobble " in the movement of the axis of a planet.

Currently the tilt of the Earth's axis to its orbital plane ( obliquity of the ecliptic ) is 23. 44 degrees, but this angle changes slowly ( over thousands of years ).

( See also Precession of the equinoxes and Pole star.