Eratosthenes.png
Summary
Description Eratosthenes.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
|
Date | |
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 |
Licensing
I, the copyright holder of this work, hereby publish it under the following license:
This file is licensed under the
Creative Commons
Attribution-Share Alike 3.0 Unported
license.
-
You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
-
Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.