Copernicus And Ptolemy Research Paper

In the path of scientific discovery, the transition from one paradigm to another can come about through a variety of different reasons. In some cases, old paradigms are rejected due to discrepancies in new observational evidence, while in others a newer method to describe the same evidence drives the transition. Copernicus’ support for the heliocentric model is an example of the latter case. As Kuhn describes in The Copernican Revolution, Copernicus’ motivation for rejecting the Ptolemaic model of planetary motion was less about his perception of the model’s correctness than it was about the model’s lack of simplicity. 

In the Ptolemaic scheme, the observed motions of the planets deviated from the expected simple orbits around the Earth. These deviations were accommodated with added intricacies to the planets’ orbital paths. One such case is retrograde movement, where a planet’s path over several days seems to stop and reverse. The Ptolemaic model accounted for this pattern with the use of epicycles, describing the planets as orbiting around points which themselves orbited the Earth in simpler paths. This more complicated system produced accurate predictions, but lacked any physical explanation.

Copernicus rejected the Ptolemaic model because of these intricacies, which he saw as refinements of an inherently flawed system. According to Kuhn, “The De Revolutionibus was written to solve the problem of the planets, which, Copernicus felt, Ptolemy and his successors had left unsolved.” (Kuhn 136) In Copernicus’ view, the intricacies of Ptolemy’s model had created a “monster” of complexity that must have hinged on a fundamental flaw. (Kuhn 139) Copernicus was sure that planetary motions could be explained with a less convoluted system based on explainable phenomena. It was through this line of reasoning that Copernicus justified a heliocentric model.

In Copernicus’ work to find a simpler model for the planetary motions, the Earth’s motion around the sun was not an initial end goal, but rather the most natural explanation. To Copernicus, “the revolutionary concept of the earth’s motion [was] initially an anomalous by-product of a proficient and devoted astronomer’s attempt to reform the techniques employed in computing planetary position.” (Kuhn 136-7) Rather than usurping the Ptolemaic model with novel observational evidence, Copernicus’ main goal was to find a more streamlined explanation for the same evidence. In doing so, the motion of the Earth emerged as a natural consequence. 

In searching for a simpler explanation for the motion of the planets, Copernicus fueled a major paradigm shift in the field of planetary astronomy. While the calculations of Ptolemaic astronomers were not incorrect, they hinged on a system that, although it matched the known observational evidence, relied on incorrect assumptions.