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Claudius Ptolemaeus
britishmuseum.org
- The Babylonians mapped the world in a flattened, disk-shaped form, but Claudius Ptolemaeus (Ptolemy) established the basis for subsequent efforts in the 2nd century ce with his eight-volume work Geōgraphikē hyphēgēsis (Guide to Geography) that showed a spherical Earth.
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Greek ethnographer Megasthenes, c. 300 BC, has been interpreted as stating that the contemporary Brahmans of India believed in a spherical Earth as the center of the universe. [2] . The knowledge of the Greeks was inherited by Ancient Rome, and Christian and Islamic realms in the Middle Ages.
Dec 28, 2017 · The idea of a spherical Earth was floated around by Pythagoras around 500 BC and validated by Aristotle a couple centuries later. If the Earth really was a sphere, Eratosthenes could use his...
Eratosthenes of Cyrene (/ ɛrəˈtɒsθəniːz /; Greek: Ἐρατοσθένης [eratostʰénɛːs]; c. 276 BC – c. 195/194 BC) was an Ancient Greek polymath: a mathematician, geographer, poet, astronomer, and music theorist. He was a man of learning, becoming the chief librarian at the Library of Alexandria.
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spherical Earth, refers to any figure of Earth as represented by a sphere. Although other models, including the geoid model (which is based on approximations of Earth’s gravitational field) and the ellipsoid model (which is based on mathematical approximations of Earth’s shape), are more accurate for many purposes, spherical models are useful as a ...
Human beings have long known that Earth is curved; however, the knowledge of Earth’s shape was not always widely known to people who had no formal education. Over the millennia, some people believed the world is flat by relying on their own observations as they stood on its surface and looked toward the horizon. In contrast, arguments for Earth having a curved surface were first posited during the 6th century bce, by the ancient Greek philosopher Pythagoras, who observed the spherical nature of other planets and posited that Earth also possesses a spherical shape. In the 5th century bce Anaxagoras noted that during lunar eclipses the curved shadow of Earth moves across the face of the Moon, leading him to infer that Earth is round. During the 4th century bce Aristotle attempted to use Earth’s circumference to calculate the size of Earth, and by about 240 bce Eratosthenes used geometry to estimate Earth’s circumference, based on the evidence of shadows and their angles relative to the Sun.
Other evidence of Earth’s curved shape was gathered by sailors and navigators. They observed that the stars appeared to move from their familiar locations in the sky to different locations as ships and their crews traveled to different parts of the world, and sailors traveling from one hemisphere to the other reported the existence of constellations they had never seen before. In addition, sailors looking toward the horizon observed that ships in the distance appeared to their view in stages, with the tops of ships’ masts, sails, and other rigging revealing themselves first before the decks and hulls appeared. Similarly, a seated person can observe the Sun appearing to sink completely below the horizon. However, if the individual stands up, the Sun’s edge will again become visible, allowing the viewer to watch it again slip below the horizon.
Modern satellite imagery and measurements of Earth’s gravitational field support the notion that Earth is not a perfect sphere but rather an oblate spheroid (that is, a sphere which is flattened at the poles). This shape derives from the way Earth spins on its axis, generating centrifugal force that causes the planet to bulge at the Equator. The pr...
The first person to determine the size of Earth was Eratosthenes of Cyrene, who produced a surprisingly good measurement using a simple scheme that combined geometrical calculations with physical observations.
The earliest globe that survives today was made in 1492 by Martin Behaim, a German navigator and geographer in the employ of King João II of Portugal. Behaim's globe recorded not only the lie of the lands being discovered by seabourne explorers, but also details of overseas commodities, market places and local trading protocols.
Oct 12, 2015 · The first known globe was made by Greek philosopher Crates of Mallus in what is now modern-day Turkey. Although now lost, the 1st century BCE writer Strabo referred to it as having a...
