EQUATORIALBULGE
Equatorial bulge
An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the centrifugal force of its rotation. A rotating body tends to form an oblate spheroid rather than a sphere. The Earth has an equatorial bulge of : that is, its diameter measured across the equatorial plane is 42.72 km more than that measured between the poles ; in other words, anyone standing at sea level on either pole may be 21.36 km closer to the earth's centrepoint than if standing at sea level on the equator. To get the Earth's mean radius, these two radii must be averaged.The above text is a snippet from Wikipedia: Equatorial bulge
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