Nicolaus Copernicus (1473-1543) published his heliocentric theory in 1543, just before his death. He realized that placing the Sun at the center of the universe with planets revolving around it made calculations and predictions much easier. This contradicted the geocentric Ptolemaic system that had been accepted for over 1400 years. Though his system was only slightly less complicated, it marked the beginning of replacing the Earth-centered view of the universe with one centered on the Sun. The Catholic Church initially ignored Copernicus' theory but eventually banned his book in 1616 as his ideas threatened established authority.