Eratosthenes

Who was Eratosthenes?

Eratosthenes of Cyrene was a Greek mathematician, geographer, poet, astronomer, and music theorist. He was a man of learning, whose love for his career at the Library of Alexandria only increased his thirst for knowledge. He invented the discipline of geography, including the terminology as we understand it today.

He is most known for being the first person to calculate the circumference of the earth, which he did by applying a measuring system using stades, or the length of stadiums during that time period. His calculation was remarkably accurate. He was also the first to calculate the tilt of the Earth’s axis. Additionally, he may have accurately calculated the distance from the earth to the sun and invented the leap day. He created the first map of the world incorporating parallels and meridians, based on the available geographical knowledge of the era. Eratosthenes was the founder of scientific chronology; he endeavored to fix the dates of the chief literary and political events from the conquest of Troy. In number theory, he introduced the sieve of Eratosthenes, an efficient method of identifying prime numbers.