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The outward acceleration caused by Earth's rotation is greater at the equator than at the poles (where is it zero), so the sphere gets deformed into an ellipsoid, which represents the shape having the lowest potential energy for a rotating, fluid body. This ellipsoid is slightly fatter around the equator than a perfect sphere would be.
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 curvature of the Earth is evident in the horizon across the image, and the bases of the buildings on the far shore are below that horizon and hidden by the sea. The simplest model for the shape of the entire Earth is a sphere. The Earth's radius is the distance from Earth's center to its surface, about 6,371 km (3,959 mi). While "radius ...
The Hill sphere, or the sphere of gravitational influence, of Earth is about 1.5 million km (930,000 mi) in radius. [ 164 ] [ n 11 ] This is the maximum distance at which Earth's gravitational influence is stronger than that of the more distant Sun and planets.
The Earth is often approximated as a sphere in geography, and the celestial sphere is an important concept in astronomy. Manufactured items including pressure vessels and most curved mirrors and lenses are based on spheres.
In a small triangle on the face of the earth, the sum of the angles is only slightly more than 180 degrees. A sphere with a spherical triangle on it. Spherical geometry or spherics (from Ancient Greek σφαιρικά) is the geometry of the two-dimensional surface of a sphere [a] or the n-dimensional surface of higher dimensional spheres.
The myth of the flat Earth, or the flat-Earth error, is a modern historical misconception that European scholars and educated people during the Middle Ages believed the Earth to be flat. [ 1 ] [ 2 ] The earliest clear documentation of the idea of a spherical Earth comes from the ancient Greeks ( 5th century BC ).
The tectonic plates of the lithosphere on Earth Earth cutaway from center to surface, the lithosphere comprising the crust and lithospheric mantle (detail not to scale). A lithosphere (from Ancient Greek λίθος (líthos) 'rocky' and σφαίρα (sphaíra) 'sphere') is the rigid, [1] outermost rocky shell of a terrestrial planet or natural satellite.