Scientific ideas, including astronomy, proliferated after the 1450s, when the printing press was invented. Although the Ptolemaic system had been immensely successful in describing general aspects of planetary motion for over 13 centuries, the discrepancies between the observed and predicted positions of some planets had become easily recognizable by the fifteenth century. Such discrepancies prompted some thinkers to reconsider the details of Ptolemy's geocentric system. However, about the time the New World was being discovered, Nicolaus Copernicus (1473-1543), a Polish canon of ecclesiastical law and astronomer, questioned whether some other configuration for the planetary system might not be simpler, more reasonable, and more aesthetically pleasing than Ptolemy's geocentric one.
Around 1514 Copernicus resurrected Aristarchus's heliocentric concept and devised a new cosmology based on it. After nearly three decades of study, Copernicus's monumental book On the Revolutions of the Heavenly Orbs was published in the year of his death, 1543. Dedicating the work to Pope Paul III, Copernicus died without seeing his theory accepted. In the universities, Copernicus's book gradually became the focus of thought-provoking study, but the public reception to what was much later a revolution in the concept of the Universe was generally indifference.
Because Copernicus still believed in the Greek idea that heavenly bodies must move in perfect circles, he accounted for deviations from uniform motion by postulating a number of epicycles and other mathematical structures. His system, therefore, was not much more accurate or simpler than Ptolemy's, but the Copernican system ultimately proved to be a tremendous step in cosmological thought. The heliocentric model was as good at explaining retrograde motion and all the observed motions as was the geocentric model. As a result, in the next century this change led to acceptance of the concept that celestial physics was not a separate consideration from, but rather an extension of terrestrial physics; Isaac Newton was later to make this clear.