The Earth's equatorial radius, or semi-major axis, is the distance from its center to the equator and equals 6,378.137 km (≈3,963.191 mi; ≈3,443.918 nmi). At [show location on an interactive map] 0° S 121.83° E, the geoid height rises to 63.42 m above the reference ellipsoid (WGS-84), giving a total radius of 6,378.200 km. The equatorial radius is often used to compare Earth with other planets.
[edit] Polar radius: b
The Earth's polar radius, or semi-minor axis, is the distance from its center to the North and South Poles, and equals 6,356.7523 km (≈3,949.903 mi; ≈3,432.372 nmi). The geoid height (WGS-84) at the North Pole is 13.6 m above the reference ellipsoid, and at the South Pole 29.5 m below the reference, giving the more exact 6,356.766 km and 6,356.723 km, respectively.
From Wikipedia
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Earth's Mass
| Bibliographic Entry | Result (w/surrounding text) | Standardized Result |
|---|---|---|
| Beichner, Robert J., John W. Jewett, and Raymond A. Serway. Physics For Scientists and Engineers. New York: Saunders College, 2000. | "Body: Earth, Mass (kg): 5.98 × 1024 kg" | 5.98 × 1024 kg |
| "Earth." The World Book Encyclopedia. Vol. 6. Chiacago: World Book Inc., 2001. | "Mass: 6,600,000,000,000,000,000,000 (6.6 sextillion) short tons (6.0 sextillion metric tons)." | 6.0 × 1024 kg |
| Smith, Peter J. The Earth. New York: Macmillan Company, 1986. | "The Solar System is dominated by the Sun, which has a mass of about 2 × 1030 kg. This is about 343,000 times the mass of the Earth." | 5.83 × 1024 kg |
| Larouse. Astronomy. New York: Facts on File Publications, 1981. | "The calculation shows that it is very close to 6.1024 kilograms (6,000 billion billion tons)." | 6.0 × 1024 kg |
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