Who proved that the Earth is round like a ball and not flat? How did he prove it?
Answers
The earliest documented mention of the concept dates from around the 5th century BC, when it appears in the writings of Greek philosophers.[1][2] In the 3rd century BC, Hellenistic astronomy established the roughly spherical shape of the Earth as a physical fact and calculated the Earth's circumference. This knowledge was gradually adopted throughout the Old World during Late Antiquity and the Middle Ages.[3][4][5][6] A practical demonstration of Earth's sphericity was achieved by Ferdinand Magellan and Juan Sebastián Elcano's circumnavigation (1519–1522).[7]
The Erdapfel, the oldest surviving terrestrial globe
Medieval artistic representation of a spherical Earth – with compartments representing earth, air, and water (c. 1400)
The concept of a spherical Earth displaced earlier beliefs in a flat Earth: In early Mesopotamian mythology, the world was portrayed as a flat disk floating in the ocean with a hemispherical sky-dome above,[8] and this forms the premise for early world maps like those of Anaximander and Hecataeus of Miletus. Other speculations on the shape of Earth include a seven-layered ziggurat or cosmic mountain, alluded to in the Avesta and ancient Persian writings (see seven climes).
The realization that the figure of the Earth is more accurately described as an ellipsoid dates to the 17th century, as described by Isaac Newton in Principia. In the early 19th century, the flattening of the earth ellipsoid was determined to be of the order of 1/300 (Delambre, Everest). The modern value as determined by the US DoD World Geodetic System since the 1960s is close to 1/298.25.[9]