2007-09-11 03:56:13 · 4 answers · asked by romantic_v 1 in Science & Mathematics ➔ Astronomy & Space
The scientific elites have known it for quite a while. Pythagoras accepted it about 500 BC. Eratosthenes of Cyrene, head of the Great Library of Alexandria had proven the earth to be round. Knowing that on a certain day, at noon, an obelisk in Luxor (s. Egypt) would cast no shadow, at exactly the same time he measured the shadow of an obelisk in Alexandria. He knew the height of the obelisk and the distance between Alexandria and Luxor; the rest is trigonometry. Claudius Ptolemy's geography is also based on the concept of the earth being round, and sun, moon and the stars circling around the earth
2007-09-11 04:29:15 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Nobody knows; it was known in antiquity from the shape of the earth's shadow on the moon during an eclipse. Of course, there were a lot of people who didn't get the word.
2007-09-11 11:02:59 · answer #2 · answered by Anonymous · 4⤊ 0⤋
Aristotle first noticed that the shadow of Earth upon the moon was round; I *think* he may be credited with it.
2007-09-11 11:10:52 · answer #3 · answered by quantumclaustrophobe 7 · 0⤊ 1⤋
Depends on which civilization you are talking about. It could be Erastothenes (Greek), Aryabhat (India) or the Chinese.
2007-09-11 12:07:54 · answer #4 · answered by ag_iitkgp 7 · 0⤊ 0⤋