And onto the all knowing Aristotle, who dominated the Greek world of science and whose theories would would be picked apart and torn up in the future while he turned in his grave. His theories though did last a very long time, especially his geocentric theory. Aristotle was a philosopher as well as a scientist and he believed everything in the universe outside of earth was perfect. He believed though that anything so perfect shouldn't be so complicated as Eudoxus' theory. Aristotle set out to create a new model of the universe, his own model.
Aristotle created a new model with 55 spheres in total, the Earth being at the center of his universe and the celestial bodies being on the outer ring of his universe. All the spheres were concentric (centers aligned) and each of the plates plus the sun and moon spun on them at different but constant velocities. The remaining rings were placed in between those of the planets and sun and mood as "buffer" rings and contained nothing on them.
By tweaking the velocities of different sphere's Aristotle could explain many of the mysteries of planetary motion, but he was still stuck on the same factor as Eudoxus. The planets were still moving backwards and were getting brighter and he couldn't explain why. Finally Aristotle came up with his theory of epicycles and deferents. Aristotle claimed that each planet spun on a small sphere called an epicycle. The center of this epicycle was attached to the deferent which was the sphere that encircled the Earth. The planet spun on its epicycle and deferent at the same time. As you see in the picture and animation below, this would explain the effect of the planets moving backwards and the effects of their colors getting brighter since they were getting closer to Earth at times.
Even though the figures didn't match up as much as Aristotle would have liked, it was still an explanation better than Eudoxus'...
