ESS220
Prof. Jin-Yi Yu
Precession
of Axis
qThere are two
kinds of precession: (1) the precession of the spin axis and (2) the precession of the
ellipse.
qEarth’s wobbling
motion is called the axial precession. It is caused by the
gravitational pull of the Sun and Moon.
qAxial precession
is a slow turning of Earth;s axis of rotation through a circular path, with a full
turn every 25,700 years.
(from Earth’s Climate: Past and Future)