Here's what we know:
* The Greeks already believed the Earth was round. Pythagoras and other philosophers before Aristotle had already argued that the Earth was round.
* Aristotle offered observations. He noted a few key pieces of evidence:
* Ships disappearing hull first. When ships sail away from the shore, they disappear hull first, with the masts remaining visible for longer. This suggests a curved surface.
* Different constellations in the sky. Travelers heading north or south would see different constellations in the sky. This suggests a curved surface, as the view of the stars changes depending on your location.
* The shape of the Earth's shadow on the Moon during a lunar eclipse. Aristotle observed that the Earth's shadow on the moon during a lunar eclipse was always round, regardless of the Earth's orientation. This strongly suggested a spherical shape.
* Aristotle's logic. He argued that the Earth must be round because it was a perfect shape, and the natural tendency of things was to move towards perfection.
It's important to note that while Aristotle's observations were valid, his reliance on the "perfect shape" argument reflects the thinking of his time. Later, more scientific methods and direct evidence would further solidify the understanding of the Earth's spherical shape.
