Eratosthenes: The Greek Mathematician Who Measured the Earth's Circumference

Eratosthenes was a Greek mathematician and astronomer who lived in the 3rd century BCE. He is best known for his accurate measurement of the circumference of the Earth, which he accomplished by using the angles of shadows cast by the Sun at different latitudes. This method, known as the "method of shadows," allowed him to calculate the circumference of the Earth with remarkable accuracy, within about 1% of the true value.

Eratosthenes was born in Cyrene, Libya (now in modern-day Libya) around 276 BCE and studied under the famous mathematician and philosopher Aristarchus of Samos. He later became the librarian of the Great Library of Alexandria, where he conducted much of his scientific research. In addition to his work on the circumference of the Earth, Eratosthenes also made significant contributions to the fields of geography, astronomy, and mathematics, including the development of a new system of latitude and longitude.

Eratosthenes' measurement of the Earth's circumference was a groundbreaking achievement that had a profound impact on the understanding of the world at the time. It not only demonstrated the possibility of accurately measuring the size of the Earth, but also provided a new way of thinking about the relationship between distance and angle, which laid the foundation for many future scientific discoveries.