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The equatorial radius is often used to compare Earth with other planets. The Earth's polar radius b, or semi-minor axis: 11 is the distance from its center to the North and South Poles, and equals 6,356.7523 km (3,949.9028 mi). Location-dependent radii Three different radii as a function of Earth's latitude.
The exceptions are objects that have been visited by a probe, or have passed close enough to Earth to be imaged. Radius is by mean geometric radius. Number of digits not an endorsement of significant figures. Mass scale shifts from × 10 15 to 10 9 kg, which is equivalent to one billion kg or 10 12 grams (Teragram – Tg).
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 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".
An Earth ellipsoid or Earth spheroid is a mathematical figure approximating the Earth's form, used as a reference frame for computations in geodesy, astronomy, and the geosciences. Various different ellipsoids have been used as approximations. It is a spheroid (an ellipsoid of revolution) whose minor axis (shorter diameter), which connects the ...
Earth is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it, taking a year (about 365.25 days) to complete one revolution.
Aristarchus of Samos. Eratosthenes ( c. 276 – c. 194/195 BC ), a Greek mathematician who calculated the circumference of the Earth and also the distance from the Earth to the Sun. Hipparchus ( c. 190 – c. 120 BC ), a Greek mathematician who measured the radii of the Sun and the Moon as well as their distances from the Earth.
Average radius of Earth: 6.378 Mm Equatorial radius of Earth 6.4 Mm Length of the Great Wall of China: 6.6 Mm Approximate length of the two longest rivers, the Nile and the Amazon: 7.821 Mm Length of the Trans-Canada Highway: 9.288 Mm Length of the Trans-Siberian Railway, longest in the world