ASTR 114 Lecture Notes - Lecture 4: Copernican Revolution, Geocentric Model, Deferent And Epicycle

• School: Binghamton University
• Department: Astronomy
• Course: ASTR 114
• Professor: Christopher A.Taylor

Document Summary

The greeks were the first people know to make models of nature. They tried to explain patterns in nature without resorting to myth or the supernatural. Earth at the center of the universe. Heavens must be perfect : objects moving on perfect spheres or in perfect circles. The most sophisticated geocentric model was created by ptolemy (a. d. 100-170) the. Ptolemaic model was sufficiently accurate enough to remain in use for 1500 years. The problem with the geocentric model is that it did not explain the retrograde motion of the planets. For example, mars appears to stop, go backwards in the sky, and then go forward again in the span of ten weeks. To explain this, the ptolemaic model had the planets actually go backward using epicycles. Epicycles: each planet moved on a smaller circle whose center moves around earth on a larger cycle. Greek knowledge was preserved first by the muslim world, and after the fall of constantinople,