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Eratosthenes: Quick Facts

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Facts

Also Known As Eratosthenes of Cyrene
Born c.276 BCE • Cyrene • Libya
Died c.194 BCE • Alexandria • Egypt
Subjects Of Study Earth • circumference • sieve of Eratosthenes

Photos

Diagram illustrating Eratosthenes' method for calculating Earth's circumference, showing the angle of sunlight at Syene and Alexandria, camels traveling between the two cities, and rays from the Sun striking Earth's surface at different angles.
A diagram on aged parchment illustrates Eratosthenes' method for measuring Earth's circumference, showing sunlight rays striking Alexandria and Syene at different angles, with labeled lines and angles representing the geometric calculation.
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Moon, Earth, and Sun diagrammed in Aristarchus's On the Sizes and Distances of the Sun and Moon
Aristarchus of Samos
Greek astronomer
Nicolaus Copernicus
Nicolaus Copernicus
Polish astronomer
James Bradley
James Bradley
English astronomer
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André-Louis Danjon
French astronomer
Ferdinand Magellan
Ferdinand Magellan
Portuguese explorer
Kelvin, William Thomson, Baron
William Thomson, Baron Kelvin
Scottish engineer, mathematician, and physicist
Bertrand Piccard, 1999.
Bertrand Piccard
Swiss aviator
Bougainville, engraving by Émile Lassalle after Maurin
Louis-Antoine de Bougainville
French navigator
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Robert Fitzroy
British scientist
Brian Jones, 1999.
Brian Jones
British aviator
Sir Joseph Banks, engraving by Ridley, 1802
Sir Joseph Banks
British naturalist
Baron Anson, detail of an oil painting by an unknown artist, c. 1745–46; in the National Maritime Museum, Greenwich, Eng.
George Anson, Baron Anson
British admiral
Léon Foucault
Léon Foucault
French physicist
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Otto von Kotzebue
Russian explorer
Eckener, 1931
Hugo Eckener
German aeronautical engineer
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Joshua Slocum
Canadian seaman
Admiral John Byron
John Byron
British admiral
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Tobias Furneaux
British explorer
Thomas Cavendish, engraving
Thomas Cavendish
English navigator and explorer
Wiley Post
Wiley Post
American pilot

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