File:Eratosthenes.png
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Eratosthenes.png (701 × 542 pixels, file size: 136 KB, MIME type: image/png)
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[edit]DescriptionEratosthenes.png |
English: Measurements taken at Alexandria and Syene.
Eratosthenes calculated the circumference of the Earth without leaving Egypt. Eratosthenes knew that on the summer solstice at local noon in the Ancient Egyptian city of Swenet (known in Greek as Syene, and in the modern day as Aswan) on the Tropic of Cancer, the sun would appear at the zenith, directly overhead (he had been told that the shadow of someone looking down a deep well would block the reflection of the Sun at noon). He also knew, from measurement, that in his hometown of Alexandria, the angle of elevation of the sun was 1/50th of a circle (7°12') south of the zenith on the solstice noon. Assuming that the Earth was spherical (360°), and that Alexandria was due north of Syene, he concluded that the meridian arc distance from Alexandria to Syene must therefore be 1/50 = 7°12'/360°, and was therefore 1/50 of the total circumference of the Earth. http://weelookang.blogspot.sg/2012/06/ejs-open-source-eratosthenes-measures.html |
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Source |
Own work http://weelookang.blogspot.sg/2012/06/ejs-open-source-eratosthenes-measures.html Picture is from http://www.shadedrelief.com/natural3/pages/textures.html // who release it to the public domain by Tom Patterson, www.shadedrelief.com. |
Author | Lookang many thanks to author of original simulation = Todd K. Timberlake author of Easy Java Simulation = Francisco Esquembre |
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[edit]I, the copyright holder of this work, hereby publish it under the following license:
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 23:59, 25 July 2015 | 701 × 542 (136 KB) | Cmdrjameson (talk | contribs) | Compressed with pngout. Reduced by 73kB (35% decrease). | |
03:14, 25 June 2012 | 701 × 542 (209 KB) | Lookang (talk | contribs) | // which is taken from http://www.shadedrelief.com/natural3/pages/textures.html // who release it to the public domain // Tom Patterson, www.shadedrelief.com. //resize to 2000x1000 by lookang using GIMP and quality reduce to 80% for 200+kb filesize | ||
03:12, 25 June 2012 | 701 × 542 (209 KB) | Lookang (talk | contribs) | // which is taken from http://www.shadedrelief.com/natural3/pages/textures.html // who release it to the public domain // Tom Patterson, www.shadedrelief.com. | ||
02:35, 22 June 2012 | No thumbnail | 701 × 542 (303 KB) | Lookang (talk | contribs) |
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