+ JMJ +
Earth Science: Grade 9 (2011-2012)
Book: Exploring Planet Earth ~ The Journey of Discovery from Early Civilization to Future Exploration by John Hudson Tiner
Eratosthenes was in born in North Africa, now Libya, and lived around 275-195 BC. He was a Greek astronomer, geographer, and mathematician. He was also appointed director of the great library of Alexandria in 236 B.C.
During his time, many people believed the earth was flat, except for the Ancient Greeks, who understood that the earth was round from several observations. One of them was this: if the earth were flat, a ship sailing away would disappear on the horizon. But instead, they observed that the ship's mast would still be visible on the horizon, while the rest of the ship would disappear. This showed that the earth was round.
Eratosthenes's greatest achievement was to measure the distance around the earth. He measured its circumference by using a deep-water well. Most of the Greeks didn't like his conclusion that their known world was tiny compared to the rest of the world. Eratosthenes will always be known as the man who measured the earth, although the ancient Greeks would probably never admit it.
~ SLED's Part-Narration / Part-Research
Additional Sources:
http://answers.askkids.com/Math/who_was_eratosthenes
