How did Ancient Greek Philosophers Know the Earth was Round?

The video explores the historical understanding of Earth's spherical shape, starting with early philosophers like Pythagoras and Plato. Aristotle provided evidence through lunar eclipses and constellations. Later, Ptolemy and others added observations about ships and horizons. Eratosthenes calculated Earth's circumference using shadows and geometry, achieving remarkable accuracy despite uncertainties in measurement units.

What was the distance between Cyrene and Alexandria according to Eratosthenes?

What was the error percentage in Eratosthenes' calculation of the Earth's circumference?