Who was the First Person to Measure the Circumferences of the Earth?

Eratosthenes is the man credited for having being the first individual to record the Circumference of the Earth. He is a prominent Greek Mathematician, historian, astronomer and Geographer whose works have had an immense impact in the various fields. Born in 276 BC in Cyrene, Eratosthenes lived his life fully concerning himself with research until his death in 195 BC (Gow 6). Eratosthenes was successful in measuring the circumference by recording angles made by shades in two different capitals positioned on the Summer Solstice. By carrying out the correct calculations through applying his vast knowledge of geometry and having the idea of how far the cities were from each other, he accurately calculated the Earth’s Circumference.

Eratosthenes having lived in Alexandria city, which was next to the entrance of River Nile in the North of Egypt, he had a clear understanding when the shadow used to be absent on a well’s bottom. Thisabsence used to happen once every year during the summer solstice in Syene town located in Southern Egypt. His observation of the absence of the shadow meant that the sun was directly above syene town at around noon of that day yearly. Similarly, Eratosthenes had an understanding that there was no time of the year that the sun could be directly above Alexandria city, his hometown even if it were during the Summer Solstice (Roller 15). Using these observations, it dawned on him that it was possible to determine the distance between the Sun directly above Alexandria through the measurement of an angle resulting from a shadow that was emanating from a vertical object. He went further to measure the distance of a shadow formed by a tall building situated in Alexandria and applied geometry in calculating the angle formed by the tall tower and the shadow. He found out that the angle was 7.2 degrees(Gow 12).

Eratosthenes went further to apply advanced geometry to come up with the inference that the angle formed by the shadow could be equal to the angle formed between Syene and Alexandria.The angle came into being throughusing the measurement from the center of the earth. He found out that a full circle was fifty times bigger than the 7.2 degrees he had come up with, thus 50 X 7.2 degrees = 360 degrees. Having been able to measure the distance between the two cities, Eratosthenes understood that it was possible to measure the Circumference of Earth through multiplying his found out length by fifty (Roller 18).

Since Eratosthenes did his best to measure the circumference of the earth, the main challenge arises from the unit of measurement used at the time. He used the stadia as the unit of measurement, and the two cities were 5,000 stadia apart(Gow 14). Unfortunately, the absence of a standard unit of measurement to use for the stadia makes it difficult to know the stadion version used by Eratosthenes hence it is not possible to determine the accuracy of his work. It is possible that the error margin could be not more than one percent or way above sixteen percent of which it is still a good margin given that the Earth has a circumference of approximately 24,860 miles (Roller 20).

Eratosthenes remains to be a talented historian, mathematician, astronomer and geographer who significantly contributed to the growth of science and its many inventions. He as well came up with a longitude and latitude system, created a calendar that also had leap years included. In astronomy, he is the brain behind the invention of an armillary sphere, which was of importance for the ancient astronomers in predicting and determining ostensible movements evidenced in the stars present in the heavens. In addition, he made a catalog compilation of stars that had over 675 stars (Roller 24). He earned more respect for having measured the Earth’s circumference and by that setting the standard and pace for several decades after that. It is possible that he could have made an attempt of measuring the length from theEarth to the sun, as well as the moon.

Lastly yet important is the fact that Eratosthenes remains a man of all time for his immense contribution that in many fields apart from coming up with circumference of the Earth. Working through as a historian, Eratosthenes worked hard to give a chronological account of events that were widely known universally by coming up with the dates when they took place. Thisaccount dated back to the Troy siege up to the moment that he was alive. In addition, he helped in explaining the selective flooding of River Nile, which had remained a baffle among scholars. He also came up with the Sieve of Eratosthenes, which was an easy algorithm for finding the prime numbers. Eratosthenes showed a lot of passion and interest in whatever he did. This led to his friends nicknaming him “beta” that refers to second in the Greek alphabet (Roller 36). This could serve as a joke that he was almost getting the point right but missed it slightly. Significantly, most of his works remain relevant to date.

Works Cited

Gow, Mary. Measuring the Earth: Eratosthenes and His Celestial Geometry. Berkeley Heights, NJ: Enslow, 2010. Print.

Roller, Duane W. Eratosthenes’ Geography. Princeton: Princeton UP, 2010. Print.