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 42.72 km (26.54 mi): that is, its diameter measured across the equatorial plane (12,756.28 km (7,926.38 mi)) is 42.72 km more than that measured between the poles (12,713.56 km (7,899.84 mi)); 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.
An often-cited result of Earth's equatorial bulge is that the highest point on Earth, measured from the center outwards, is the peak of Mount Chimborazo in Ecuador, rather than Mount Everest. But since the ocean, like the Earth and the atmosphere, bulges, Chimborazo is not as high above sea level as Everest is.
Read more about Equatorial Bulge: The Equilibrium As A Balance of Energies, Differences in Gravitational Acceleration, Satellite Orbits, Other Celestial Bodies, Mathematical Expression
Famous quotes containing the word bulge:
“The young men float on their backs, their white bellies bulge to
the sun, they do not ask who seizes fast to them,
They do not know who puffs and declines with pendant and bending arch,
They do not think whom they souse with spray.”
—Walt Whitman (1819–1892)