By measuring the length of the shadow cast by a vertical stick during the solstice noon, he could figure out what angle the Sun made with the vertical direction at Alexandria.Īnd the answer he got was one-fiftieth of a circle, or 7.2 degrees. Sure, the Sun came closer to being directly overhead at Noon on the Summer Solstice in Alexandria than at any other time during the year, but vertical objects still cast shadows.Īnd - like any good scientist - Eratosthenes did the experiment. If you go outside during sunset a day or two after the new moon, here's the sight you're likely to encounter.īut Eratosthenes knew that this wasn't the case where he was, in Alexandria. And if you knew only of the two most important astronomical objects in the sky - the Sun and the Moon - you yourself might reach the same conclusions. Indeed, there are many ancient references to the Earth being shaped like a disc. "How brave the sailors of 1492 must have been," you might imagine, "to travel towards the edge of the world without fear of falling off!" One of the most enduring myths that children grow up with is the idea that Columbus was the only one of his time who believed that the Earth was round everyone else believed it was flat. Emma Miler Bolenius, American Schoolbook Author, 1919 Columbus had to fight these foolish beliefs in order to get men to sail with him. They believed the Atlantic Ocean to be filled with monsters large enough to devour their ships, and with fearful waterfalls over which their frail vessels would plunge to destruction.
"When Columbus lived, people thought that the earth was flat.
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