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| | Earth radius - Facts, Information, and Encyclopedia Reference article |
 | | The radius of Earth (or any planet) is the distance from its centre to a point on its surface at mean sea level. |
 | | The Earth's equatorial radius, or semi-major axis, is the distance from its centre to the equator and equals 6,378.135 km (≈3,963.189 mi; ≈3,443.917 nm). |
 | | It is this radius that would be used to approximate the ellipsoid's average great ellipse (i.e., this is the equivalent spherical "great-circle" radius of the ellipsoid). For Earth, equals 6,372.795477598 km (≈3,959.871 mi; ≈3,441.034 nm). |
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