sentences:  The more epicycles proved to have more accurate measurements of how the planets were truly positioned, "although not enough to get excited about".Over the years, the Ptolemaic system become less reliable and less accurate which became obsolete to Copernicus's system.The Copernican system can be summarized in several propositions, as Copernicus himself did in his early "Commentariolus" that he handed only to friends, probably in the 1510s.