Copernicus and the Need for EpicyclesThere is a common misconception that the Copernican model did away with the need for epicycles. This is not true, because Copernicus was able to rid himself of the long-held notion that the Earth was the center of the Solar system, but he did not question the assumption of uniform circular motion. Thus, in the Copernican model the Sun was at the center, but the planets still executed uniform circular motion about it. As we shall see later, the orbits of the planets are not circles, they are actually ellipses. As a consequence, the Copernican model, with it assumption of uniform circular motion, still could not explain all the details of planetary motion on the celestial sphere without epicycles. The difference was that the Copernican system required many fewer epicyclesthan the Ptolemaic system because it moved the Sun to the center.The Copernican RevolutionWe noted earlier that 3 incorrect ideas held back the development of modern
This is the end of the preview.
access the rest of the document.