Theories+-+Geocentric+(should+reference+Pythagoras,+Aristotle,+Hipparcus,+Ptolemy,+Tycho+Brahe)

The Geocentric model, or theory, is the belief that the Earth is the center of the universe and that everything revolves around it as developed by Ptolemy. Many ancient civilizations, such as ancient Greece for example, were under the notion that this is the form the universe took, and many philosophers, including Aristotle supported it. Another accompanying theory is that the orbits of the planets were not elliptical, but were instead circular. The ancient Greeks were again the first to develop this theory, and it was not challenged in Western culture until the 17th century by Copernicus and Kepler.
 * __Geocentrism__**

The original Greek model was created by Anaximander, and showed an almost cylindrical form of the universe, with a spherical Earth in the center, and that the sun, moon, and stars were holes in invisible rings surrounding Earth showing a hidden fire. The followers of Pythagoras also believed that the Earth was spherical, but that the Earth revolved around an unseen fire, not that it revolved around Earth.
 * __Ancient Greek Geocentrism__**

In the Ptolemaic model, each planet is moved by two or more spheres: one called it's deferent, and the others called it's epicycles. (A better illustration explaining deferents and epicycles can be found at [] The Copernican model was the first to challenge the Geocentric beliefs, and was the first Heliocentric system to be proposed. Copernicus claimed that all of the planets including the Earth and moon revolved around the sun, something we now know to be true. The only difference between the Copernic model and modern belief is that it didn't prove any more accurate than the Ptolemaic system due to the fact that it used circular orbits.
 * __Ptolemaic Model__**
 * __Copernican Model__**