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as the shape of Earth's land surface as it rises above and falls below the sea. As the science of geodesy measured Earth more accurately, the shape of the geoid was first found not to be a perfect sphere but to approximate an oblate spheroid, a specific type of ellipsoid.
The shadow of Earth on the Moon during a lunar eclipse is always a dark circle that moves from one side of the Moon to the other (partially grazing it during a partial eclipse). The only shape that casts a round shadow no matter which direction it is pointed is a sphere, and the ancient Greeks deduced that this must mean Earth is spherical. [8]
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 monk Bede (c. 672–735) wrote in his influential treatise on computus, The Reckoning of Time, that Earth was round. He explained the unequal length of daylight from "the roundness of the Earth, for not without reason is it called 'the orb of the world' on the pages of Holy Scripture and of ordinary literature.
Earth's circumference is the distance around Earth. Measured around the equator, it is 40,075.017 km (24,901.461 mi). Measured passing through the poles, the circumference is 40,007.863 km (24,859.734 mi). [1] Treating the Earth as a sphere, its circumference would be its single most important measurement. [2]
Criticism of the flat Earth theory should be balanced by criticism of the round Earth theory. The article lead should begin with a pure definition. Criticism should come second, e.g.:"Flat Earth refers to the Earth's flat shape. Skeptics say the Earth is round." How to recognise
[citation needed] It was also typically held in the aboriginal cultures of the Americas, and a flat Earth domed by the firmament in the shape of an inverted bowl is common in pre-scientific societies. [7] "Center" is well-defined in a Flat Earth model. A flat Earth would have a definite geographic center.
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.