Mans First Encounters with the Universe.
Since the beginning of time man has looked to the sky to observe what he saw there. Some have even tried to reason the patterns that were visible. The ancient Babylonians mostly ignored how it worked and merely followed and studied the paths the heavenly objects took. The ancient Greeks took that a step further. They wanted to know how the universe actually looked. Pythagoras was the first to set a blueprint to the extraterrestrial forms. He was followed by Plato and Aristotle. Finally, Ptolemy wrapped it up neatly to complete the model that stood for many years. Although his model is incomplete, Ptolemy based his ideas on the information and aesthetics of the time in which he lived. Pythagoras paved the way for astronomy by describing the universe and how it all fit together. In about 600 B.C., Pythagoras created possibly the first model of the universe. It was geocentric which meant the objects in space revolved around the earth. In the model the earth and all the ethereal bodies were perfect spheres. They also traveled in perfect spheres. These beliefs stemmed directly from the idea of beauty in this time period. To account for the traditional motion of the planets, Pythagoras devised that the planets also orbited an epicenter that sometimes made them appear to be going backwards in the sky. The stars themselves were embedded in a perfect sphere that encompassed the entire universe as the ancient Greeks knew it. .
Aristotle added his own view to the geocentric representation in the third century B.C. Likewise; he added the ideas of natural and forced motion. He also speculated that between the earth and the heavens were the four elements: earth, water, air, and fire. The model, however, was not quite complete. Claudius Ptolemy continued where his predecessors left off. He worked at the library at Alexandria in about 125 C.E. He had access to a great store of knowledge.