(384-322BC)
Aristotle was another Greek to find his niche in astronomy. Aristotle also believed in a "perfect universe", theorizing that the Earth was a perfect sphere, along with the other planets; and that the entire universe itself was a sphere and did in fact end at a certain point. He cemented his theory of a spherical Earth by looking at the lunar eclipse, and realizing that the shadow the eclipse showed was curved, meaning the Earth was round.
Aristotle also believed that all of the planets in the known universe were composed of strictly four elements: earth, water, air and fire. And that these bodies orbited the Earth in a circular fashion (similar to Pythagorean's theory). And beyond the planets, were in fact the stars, which Aristotle deemed to be composed of a fifth element called "ether".
Aristotle had a different approach to astronomy than Pythagoras, being a philosophical view. Instead of attempting to explain things through fact and science, he developed his own theories using only his mind and imagination.
A sketch of Aristotle's view of the universe, also with the Earth in the center.
