An ancient theory is known as geocentric theory which positions the Earth at the center of the universe, and the stars, including the Sun, rotating around the Earth. This theory was valid in various civilizations of antiquity. This theory was elaborated and proposed by Aristotle and it was in force until the 16th century, in the version completed by Claudius Ptolemy in the 2nd century BC. C., in the work called El Almagest, in which the so-called epicycles, equants and deferents were introduced. This was replaced by the heliocentric theory.
On the other hand, geocentrism does not present any solution to the problems that are related to the movements of the celestial bodies, among which the movements of the planets stand out, this theory was in force in the most remote civilizations, in Babylon this was the vision of the universe.
On the other hand, it is important to note that the essential postulates of geocentric theory date back to ancient times, this being the perception of the world in space that was also believed to be functional in ancient Babylonian times, just to give one example. Focusing on the writings, in The Almagest Ptolemy gives an explanation of how the planets, the Sun and also the stars are revolving around the Earth, introducing the concepts and explanations of the geometric models that created the ancient epicycles, equations and deferents, which were developed to understand the apparent movements, speed and direction variations of the planets that served to keep the geocentric theory standing.
The system that Ptolemy described shows that versions of the geocentric model functioned by this complex interaction between circles. Ptolemy had the perception that each planet revolved around a circle which he called the epicycle and at the same time, the epicycle orbited in a larger circle than the one called deferential, all thus rotating around the planet Earth. For its part, the center of the deferent would not be the Earth itself, but a point that was close to the midpoint of the distance between the Earth and the equator. For his part, regarding the idea of the equator, Ptolemy achieved a perfect solution to be able tojustify the numerous discrepancies and criticisms that the geocentric model was already receiving by then.
