When did people realize the Earth is round and not flat? Discover the history of how scientists like Aristotle and Eratosthenes proved the spherical shape of Earth over 2,000 years ago.   Introduction   The question “When did scientists find out that the Earth is a sphere and not flat?” often comes up in history and science discussions. Contrary to popular belief, the fact that Earth is round was discovered thousands of years ago — long before modern space travel. Let’s explore how ancient scientists figured it out.   Ancient Greek Discoveries Pythagoras (6th century BCE)   The Greek philosopher…