Precession
Aside from the tilt, the axis also wobbles like a top. A complete wobble cycle is more
or less 26,000 years. This motion is caused by tidal forces from the Sun and Moon.As
a result of this, the pole star of the Earth changes every 26,00 years.It is estimated that
after about 11,700 years from now, our pole star will be a blue-white star 'Vega'!!!
The Milankovitch Cycles are among the arguments fielded by detractors of the Global
Warming concept. According to them, the Earth’s current warming is just a part of a
series of cyclical events that take thousands of years to complete, and hence cannot be
prevented.
Credit: "Precession and seasons" (Wikimedia Commons)
As a result of the Milankovitch cycle, every 11000 years, the sequence of season
changes.