Eratosthenes is known for calculating the Earth's circumference using geometric methods and observations of sunlight, contributing greatly to the field of physical geography.
Eratosthenes made a significant contribution to the field of physical geography by being the first person to calculate the Earth's circumference with relatively high accuracy. His method involved geometric principles and observing the Sun's rays at different locations.
While there is some uncertainty about the exact stadia measurement he used—whether his calculation was off by as much as 20% with the Olympic stadium or remarkably within 1% of the true value using another measure of stadia—his method was stellar for his time. Eratosthenes's ingenious approach used the angle of sunlight at two points, Syene and Alexandria, to estimate the Earth's size. This advancement laid foundational knowledge for future exploration and understanding of our planet.