Galileo's research led him to become an advocate of the work of the Polish astronomer Nicolaus Copernicus (1473-1573). However, the Copernican theory of a sun-centered solar system conflicted with the teachings of the powerful Roman Catholic Church, which essentially ruled Italy at the time. Church teachings contended that Earth, not the sun, was at the center of the universe. In 1633, Galileo was brought before the Roman Inquisition, a judicial system established by the papacy in 1542 to regulate church doctrine. This included the banning of books that conflicted with church teachings. The Roman Inquisition had its roots in the Inquisition of the Middle Ages, the purpose of which was to seek out and prosecute heretics, considered enemies of the state.
Today, Galileo is recognized for making important contributions to the study of motion and astronomy. His work influenced later scientists such as the English mathematician and physicist Sir Isaac Newton, who developed the law of universal gravitation. In 1992, the Vatican formally acknowledged its mistake in condemning Galileo.