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Unformatted text preview: It is not a perfect sphere; technically it is classified as an oblate spheroid or oblate ellipsoid (a sphere flattened at the poles.) Axial Tilt ( obliquity of the ecliptic) Axial tilt is the angle between the planets rotational axis and the normal of the plane of orbit. Today the Earth's axial tilt is about 23.5 degrees, which largely accounts for our seasons. Because of the periodic variations of this angle the severity of the Earth's seasons changes. With less axial tilt the Sun's solar radiation is more evenly distributed between winter and summer. However, less tilt also increases the difference in radiation receipts between the equatorial and polar regions. http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm...
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- Winter '08
- Geography, axial tilt, North Antarctic Circle, n oblate spheroid