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Eratosthenes’ Circumference of the Earth
Eratosthenes was a brilliant mathematician, scholar and poet that was able to calculate the circumference of the Earth when he lived in late 200s B.C. Eratosthenes is highly praised for this great accomplishment because he did not have any modern tools that we have today and was able to calculate the Earth’s circumference, all while never leaving Egypt. But, how did he do this? And how accurate or close was his answer to the real circumference of the Earth? Eratosthenes life began roughly around the year of 276 B.C., in a Greek colony of Syene, modern day Libya. Once Eratosthenes was of age, he traveled to Athens to further his education. Eratosthenes had many interests ranging from stoicism, philosophy,*…show more content…*

It was during his time at the library that Eratosthenes made several important contributions to mathematics and science. Around the year 255 B.C., he had invented the armillary sphere. Which was a sphere model of “spherical framework of rings, centered on Earth, that represented lines of celestial longitude and latitude and other astronomically important features such as the ecliptic” (Wikipedia, “Armillary Sphere”). Eratosthenes was credited in On the Circular Motions of the Celestial Bodies by Cleomedes with having calculated the Earths circumference around 240 B.C. With his curiosity of Earth circumference, Eratosthenes continued on with his knowledge of Earth and began to sketch the planet. With the vast resources at his disposal from the Library in Alexandria, Eratosthenes was able to create a map of the entire known world. “…even dividing the Earth into five climate zones: two freezing zones*…show more content…*

Eratosthenes, using the conversion of 185 meter to a stade, calculated the Earth’s circumference to be about 46,620 kilometers. With today’s modern technology, we have been able to calculate the Earth’s circumference to a degree of more accuracy, which has been established as 40,008 kilometers. We can obliviously tell that Eratosthenes answer was incorrect. Eratosthenes over calculated by 6,545 kilometer; leaving himself to about a 16.3% margin of error. We can contribute these errors to some assumptions Eratosthenes made when calculating his answers. First was that he assumed that the Earth was a sphere, when in reality a sphere is really close to the Earths actually shape, but not quite. The second was that he assumed that the distance between Alexandria and Syene was 5000 stades. Eratosthenes could not accurately measure the distance between the two cities during this time period, therefore, he could not ever really get the exact circumference of the Earth, but he could have lowered his margin of error by having a somewhat more accurate distance. The third and final assumption Eratosthenes made was Alexandria and Syene laid on the same meridian. “If we repeated Eratosthenes’ calculation with more accurate data, the result is 40,074 kilometers, which is 66 kilometers different (0.16%) from the currently accepted circumference of the Earth” (Wikipedia,

It was during his time at the library that Eratosthenes made several important contributions to mathematics and science. Around the year 255 B.C., he had invented the armillary sphere. Which was a sphere model of “spherical framework of rings, centered on Earth, that represented lines of celestial longitude and latitude and other astronomically important features such as the ecliptic” (Wikipedia, “Armillary Sphere”). Eratosthenes was credited in On the Circular Motions of the Celestial Bodies by Cleomedes with having calculated the Earths circumference around 240 B.C. With his curiosity of Earth circumference, Eratosthenes continued on with his knowledge of Earth and began to sketch the planet. With the vast resources at his disposal from the Library in Alexandria, Eratosthenes was able to create a map of the entire known world. “…even dividing the Earth into five climate zones: two freezing zones

Eratosthenes, using the conversion of 185 meter to a stade, calculated the Earth’s circumference to be about 46,620 kilometers. With today’s modern technology, we have been able to calculate the Earth’s circumference to a degree of more accuracy, which has been established as 40,008 kilometers. We can obliviously tell that Eratosthenes answer was incorrect. Eratosthenes over calculated by 6,545 kilometer; leaving himself to about a 16.3% margin of error. We can contribute these errors to some assumptions Eratosthenes made when calculating his answers. First was that he assumed that the Earth was a sphere, when in reality a sphere is really close to the Earths actually shape, but not quite. The second was that he assumed that the distance between Alexandria and Syene was 5000 stades. Eratosthenes could not accurately measure the distance between the two cities during this time period, therefore, he could not ever really get the exact circumference of the Earth, but he could have lowered his margin of error by having a somewhat more accurate distance. The third and final assumption Eratosthenes made was Alexandria and Syene laid on the same meridian. “If we repeated Eratosthenes’ calculation with more accurate data, the result is 40,074 kilometers, which is 66 kilometers different (0.16%) from the currently accepted circumference of the Earth” (Wikipedia,

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