Transcript: Ice ages are periods of global cooling by a few degrees, up to ten or so degrees, that occur at irregular intervals of tens of thousands to hundreds of thousands of years. The causes of ice ages are complex, but over the past few million years, there is good evidence that variations in the Earth’s orbit has contributed to the cause of ice ages, in particular the Earth’s tilt on it’s axis, which is varied from twenty-two to twenty-five degrees, influenced primarily by Jupiter. Other influences in the ice age could be the geomagnetic reversals that occur every few hundred thousand years in the Earth’s core which are also influenced by orbital dynamics. Astronomers are only beginning to unravel the effects of subtle changes in the Earth’s orbit and their impact on global climate.