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AP Human Geography: Eratosthenes

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The Greeks were a civilization that have been admired and studied by historians for over hundreds of years before their tragic collapse. An extraordinary individual named Eratosthenes was born in a small Greek colony called Cyrene, he was a very talented Grecian who has a young man traveled to Athens to pursue studies. In all my years of reading about the ancient Greeks and studying geography, the name “Eratosthenes” had always come up. Taking AP Human Geography last year, my teacher was captivated by Eratosthenes and he would continuously state facts about him. But a unique statement struck me and could never leave my head. When talking about the earths tilt, latitude, and longitude he told us that someone over 2250 years ago, with only basic …show more content…

(between June 20th and June 22nd) the Greek Astronomer, Eratosthenes had heard of a famous well in a Egyptian City called Syene (now known as Aswan) located around the Nile River. He knew that every year on the solstice, there was no shadow on the bottom of well but instead the rays of sunlight reflected back, and not on the sides of the well as on other days. He came to a conclusion that the sun was directly overhead in Syene at noon every year. He knew that in his hometown Alexindra, the sun was never directly above him even on the solstice. He assembled a pole in Alexindra to study and calculate the shadows position eventually proving that no sun was directly above but faintly south. Knowing that the earth was curved and knowing the distance between the two cities, Syene and Alexandra he calculated the planets circumference by doing simple geometry. “Eratosthenes could measure the angle of the Sun’s rays off the vertical by dividing the length of the leg opposite the angle (the length of the shadow) by the leg adjacent to the angle (the height of the pole). This gave him an angle of 7.12 degrees. He knew that the circumference of Earth constituted a circle of 360 degrees, so 7.12 (or 7.2, to divide 360 evenly by 50) degrees would be about one-fiftieth of the circumference. He also knew the approximate distance between Alexandria and Syene, so he could set up this …show more content…

The length of those so called stadions were the length of an athletic stadium, but unfortunately not all of them were built the same size or had the equal length. In Greek the usual stadion was roughly 185 meters (607 feet) and the Egyptians stadion was around 157.5 meters (517 feet). As of today historians and mathematicians still argue on which version Eratosthenes used. If he had used the Greeks measurement, his calculations would have been off by 16 percent! If he had used the Egyptian one, his mathematical skills would have been of by less than 2 percent of earths actual circumference which is 24,860 miles (40,008

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