Geocentrism and heliocentrism
Just as we have seen some of the possible origins of the universe according to different beliefs, there have also been differences in the concept of the universe.
The oldest civilizations believed that the universe consisted of a flat and immobile Earth, and a sky located above, in which the stars would be.
The Greeks were the first to observe and deduce that the Earth is a spherical body that floats in space with the other stars. From then on, other more scientific theories emerged such as geocentrism and heliocentrism.
The geocentric is the theory that the Earth is at the center of the universe, and the sun and all celestial bodies revolving around it .
This theory was accepted by various ancient civilizations. In the second century, Ptolemy collected the dominant ideas of the time and introduced epicycles, a theory that was in force until it was replaced in the sixteenth century by heliocentrism.
According to Ptolemy, the Earth was in the center, and around it the Sun , the Moon and all the celestial stars would rotate in increasingly larger spheres (epicycles).
The stars are fixed in a vault that, like the rest of the stars, would also rotate around the Earth.
The epicycles are a geometric model devised three centuries before Ptolemy that allowed the ancient Greeks to explain the variations in the speed and direction of the apparent movement of the Moon , the Sun , and the planets.