Eratosthenes, a scholar of the Hellenistic period residing in Alexandria, Egypt, calculated the Earth’s circumference with remarkable accuracy using simple geometric principles and observations. He compared the angle of the sun’s rays at noon on the summer solstice in two different locations, Alexandria and Syene (modern-day Aswan). Knowing the distance between these locations, he extrapolated this to a full circle, providing an impressively close approximation of Earth’s true size.
This calculation stands as a testament to the power of human ingenuity and scientific observation in antiquity. It demonstrates an early understanding of Earth’s spherical nature and represents a significant milestone in the history of geodesy and astronomy. His work laid the foundation for further geographic exploration and cartography, shaping our understanding of the planet’s dimensions and our place within the cosmos.
