 Earth's Orbit
 The Milankovitch theory, named after the Yugoslav mathematician who first proposed it, is the astronomical or orbital theory of climate variations. Since these ideas were put forward, much evidence from palaeoclimatic records has been found to support the theory. The original Milankovitch theory identifies three types of variation in the Earth's orbit around the Sun which could act as mechanisms to change the global climate. These include changes in the tilt of the Earths axis (obliquity), changes in the shape of Earth's orbit (eccentricity) and the shifting of the equinoxes (precession). Each variation has its specific time period, the shortest being 22,000 years and the longest being 96,000 years.
The three orbital variations together affect the total amount of sunlight received by the Earth, and distribution of that sunlight at different latitudes and at different times. With time periods measured in tens of thousands of years, one would expect that changes in climate as a result of orbital variations would occur over similar time periods. Indeed, the Milankovitch theory of climate change has been used to explain the global climate of the last 2 million years, with changes between warmer interglacial periods and colder Ice Ages occurring over a 100,00 year cycle, as predicted by the Milankovitch theory of climate change.
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