Introduction
Every schoolchild knows that in the past, people believed that the Sun is a planet rotating around Earth. The geocentric model existed for ages, and only a long time after was replaced by the correct heliocentric one. However, I have always asked myself what could have deluded the ancients for such a long time. It seems to me that the short version of this story does not demonstrate all the intricacies behind it. Besides, we know that Ptolemy tried to account for the fact that the orbits of the planets deviate from perfect circles and even decided to introduce two small shifts into his model. This could mean that the precision of his guesses was relatively high, which might have been the reason for postponing the disclaimer of the model. I decided that this issue deserves close attention and exploration.
Search Log
First, I decided to investigate what Google can offer on the topic. I typed “Ptolemaic Model” in the search engine, and the first link directed me to the Polaris Project of Iowa State University. There I read a brief overview of Ptolemy’s activities and the description of his model in comparison with that created by Copernicus. I inspected the site further but found no academic materials or links to the original works. I presumed that the site was created for educational purposes in order to provide students with a summary of basic facts. The second link google offered was Wikipedia. It is rather useful if you want to get a general idea of some object, person, or phenomenon, but being a secondary source, it could not give me the specific information I was looking for. In the search for peer-reviewed articles I resorted to the assistance of google scholar. I indicated in the settings that the search results had to be published not earlier than in 2012 because I wanted to get the most recent data possible. However, it gave me so many irrelevant articles, that I had to use the strategy “allintitle: Ptolemaic model” – this considerably limited the search. I chose the article called Optimizing the Ptolemaic Model of Planetary and Solar Motion by Ilia Rushkin, submitted and revised in 2015. The title attracted my attention, so I checked the name of the author on LinkedIn and found out that he is a Research Scientist at Harvard University, who published a lot of articles in mathematics and astronomy. Thus, the source seemed to be reliable and I downloaded the pdf version.
Conclusion
Having read the article I discovered that my previous knowledge about the models of the universe was indeed very sketchy. For instance, I had never known before that there existed combined models with the Sun going around the Earth and the planets rotating around the Sun (Rushkin 11).
However, the most surprising thing I have learnt was that if Ptolemy had made the ratio of both shifts 5/3, the model could have achieved the highest level of precision being totally wrong in its basic assumption. It means that the model’s deficiencies would not have led Kepler to refute it (Rushkin 11). These modifications would have made the model compatible with observations and this would have delayed Kepler’s laws by several decades (Rushkin 11).
It is curious to know that Ptolemy could have surpassed Kepler if he had decided to step aside from the aesthetic laws of Ancient Greece and had transformed a circle into an ellipse. It seems rather ridiculous for a modern person to learn that the pursuit of perfection could have prevented a genius from one of the greatest scientific discoveries of his time. However, paying tribute to culture and arts deserves recognition.
Works Cited
Rushkin, Ilia. Optimizing the Ptolemaic Model of Planetary and Solar Motion. Web.