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Earth radius (denoted as R 🜨 or R E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid (an oblate ellipsoid), the radius ranges from a maximum (equatorial radius, denoted a) of nearly 6,378 km (3,963 mi) to a minimum (polar radius, denoted b) of nearly 6,357 km (3,950 mi).
The Earth's radius is the distance from Earth's center to its surface, about 6,371 km (3,959 mi). While "radius" normally is a characteristic of perfect spheres, the Earth deviates from spherical by only a third of a percent, sufficiently close to treat it as a sphere in many contexts and justifying the term "the radius of the Earth".
The mass of the oceans is approximately 1.35 × 10 18 metric tons or about 1/4400 of Earth's total mass. The oceans cover an area of 361.8 million km 2 (139.7 million sq mi) with a mean depth of 3,682 m (12,080 ft), resulting in an estimated volume of 1.332 billion km 3 (320 million cu mi).
R E is central body's equatorial radius (6 378 137 m for Earth), ω E is the central body's rotation rate ( 7.292 115 × 10 −5 rad/s for Earth), GM E is the product of the universal constant of gravitation and the central body's mass ( 3.986 004 418 × 10 14 m 3 /s 2 for Earth).
As one degree is 1 / 360 of a circle, one minute of arc is 1 / 21600 of a circle – such that the polar circumference of the Earth would be exactly 21,600 miles. Gunter used Snellius's circumference to define a nautical mile as 6,080 feet, the length of one minute of arc at 48 degrees latitude.
The polar Earth's circumference is simply four times quarter meridian: = The perimeter of a meridian ellipse can also be rewritten in the form of a rectifying circle perimeter, C p = 2πM r. Therefore, the rectifying Earth radius is: = (+) / It can be evaluated as 6 367 449.146 m.
The planet is about the size of Venus, so slightly smaller than Earth, and may be temperate enough to support life, the researchers said. Dubbed Gliese 12 b, the planet takes 12.8 days to orbit a ...
The above equation describes the Earth's gravitational potential, not the geoid itself, at location ,,, the co-ordinate being the geocentric radius, i.e., distance from the Earth's centre. The geoid is a particular equipotential surface, [ 27 ] and is somewhat involved to compute.