User:Spaceman13/Sandbox

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[edit] Shape

Main article: Figure of the Earth
Size comparison of inner planets (left to right): Mercury, Venus, Earth, and Mars
Size comparison of inner planets (left to right): Mercury, Venus, Earth, and Mars

The Earth's shape is very close to an oblate spheroid—a rounded shape with a bulge around the equator—although the precise shape (the geoid) varies from this by up to 100 metres (327 ft).[1] The average diameter of the reference spheroid is about 12,742 km (7,913 mi). More approximately the distance is 40,000 km/π because the metre was originally defined as 1/10,000,000 of the distance from the equator to the north pole through Paris, France.[2]

The rotation of the Earth creates the equatorial bulge so that the equatorial diameter is 43 km (27 mi) larger than the pole to pole diameter.[3] The largest local deviations in the rocky surface of the Earth are Mount Everest (8,848 m [29,028 ft] above local sea level) and the Mariana Trench (10,911 m [35,798 ft] below local sea level). Hence compared to a perfect ellipsoid, the Earth has a tolerance of about one part in about 584, or 0.17%, which is less than the 0.22% tolerance allowed in billiard balls.[4] Because of the bulge, the feature farthest from the center of the Earth is actually Mount Chimborazo in Ecuador.[5]

[edit] Notes

  1. ^ Milbert, D. G.; Smith, D. A.. Converting GPS Height into NAVD88 Elevation with the GEOID96 Geoid Height Model. National Geodetic Survey, NOAA. Retrieved on 2007-03-07.
  2. ^ Mohr, P.J.; Taylor, B.N. (October, 2000). Unit of length (meter). NIST Reference on Constants, Units, and Uncertainty. NIST Physics Laboratory. Retrieved on 2007-04-23.
  3. ^ Sandwell, D. T.; Smith, W. H. F. (Jul7 26, 2006). Exploring the Ocean Basins with Satellite Altimeter Data. NOAA/NGDC. Retrieved on 2007-04-21.
  4. ^ Staff (November, 2001). WPA Tournament Table & Equipment Specifications. World Pool-Billiards Association. Retrieved on 2007-03-10.
  5. ^ Senne, Joseph H. (2000). "Did Edmund Hillary Climb the Wrong Mountain". Professional Surveyor 20 (5).