11. Ancient Greek, ancient Roman and medieval philosophers usually combined the geocentric model with a spherical Earth. 12. While maintaining the physical reality of the geocentric model , he criticized elements of the Ptolemic models. 13. In these geocentric models the stars and planets are carried around the Earth on spheres or circles. 14. This is known as the geocentric model of the Universe, or the Ptolemaic system, named after Ptolemy. 15. The nine spheres are concentric, as in the standard medieval geocentric model of cosmology, which was derived from Ptolemy. 16. The Tusi couple was later employed in Ibn al-Shatir's geocentric model and Nicolaus Copernicus'Copernican model. 17. It's possible to construct a geocentric model of the universe, and it worked for hundreds and hundreds of years. 18. Childrey, though in other ways a convinced Baconian, argued that Bacon's geocentric model of the cosmos was incorrect. 19. The geocentric model served as the predominant description of the cosmos in many ancient civilizations, such as those of Aristotle and Ptolemy. 20. In the 4th century BC, two influential Greek philosophers, Plato and his student Aristotle, wrote works based on the geocentric model .
