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What Are the Polar & Equatorial Diameters of the Earth?

When satellites and rockets were first sent into space, they gave scientists a unique opportunity to start looking at the Earth in a different way. When humans were earthbound, it was impossible to actually prove the size of the planet or even show it was round and not flat. Images taken from the original satellites, the Apollo missions, the Hubble telescope and the Space Shuttle have allowed astrophysicists to accurately measure the dimensions of the Earth.

Poles and Equator
- The poles of the Earth are located in Antarctica to the south and the Arctic to the north. The equator is an imaginary line running around the center of the planet and it runs through countries such as Brazil, Columbia, Indonesia, Kenya and Uganda. Unlike the equator, there is no set line to measure from pole-to-pole. Measuring these lines would give results for the circumference of the Earth. The diameter is a measurement going from one side of the Earth to the other through the Earth's core.
Polar Diameter
- The diameter of the Earth from pole to pole is 7,899.98 miles (12,712.2 kilometers). This measurement is not taken as straight up and down the planet, but takes into account the rotational axis of the Earth. This means the distance is on a slight diagonal.
Equatorial Diameter
- Across the center of the Earth, the diameter is slightly larger at 7,926.67 miles (12,755.7 kilometers). Although this measurement is also on a slight diagonal because of the Earth's axis, it is taken from points on the equatorial line. An interesting fact using this measurement is that Mount Everest is no longer the highest mountain. Mount Chimborazo in the Ecuadorian Andes works out at over 2 kilometers taller, although Everest remains the highest because of distance above sea level.
Equatorial Bulge
- As can be seen from the last two sections, the Earth is not spherical, but is in fact 26.5 miles (42.72 kilometers) wider at the equator than at the pole. This is caused by gravity and the planet's rotation making the Earth flatter at the top by a ratio of 1-to-298.2575. This is noted on all planets and moons in the solar system and is referred to as the flattening ratio.

Astronomy