Here's a breakdown:
* Ancient Greeks: Philosophers like Pythagoras (c. 570 – 495 BCE) and Aristotle (384 – 322 BCE) were among the first to propose the Earth was a sphere based on observations like the changing position of stars and the circular shadow cast by the Earth during lunar eclipses.
* Eratosthenes: This Greek scholar, around 240 BCE, made the first attempt to calculate the circumference of the Earth. His methods, while imperfect, confirmed the spherical nature of the Earth.
* Medieval Islamic World: Muslim scholars continued the exploration of astronomy and geography, further solidifying the understanding of the Earth's shape.
* Ferdinand Magellan: The first circumnavigation of the globe in the 16th century provided concrete evidence of the Earth's sphericity.
The idea of a flat Earth was largely a fringe theory that existed in parallel with the mainstream understanding of the spherical Earth. It wasn't until the rise of modern science that the concept of a flat Earth was largely dismissed.
Therefore, there is no single individual who "first" said the Earth is not flat. It was a gradual understanding developed over centuries through observations, calculations, and voyages of exploration.
