Regrettably, De Revolutionibus Orbium Coelestium was placed on the Catholic Church’s list of banned books in 1616, where it remained until 1835. Before it was banned, word of the heliocentric model nonetheless spread among astronomers and scholars. Eventually, Galileo Galilei (1564–1642) used astronomical observations to prove that the heliocentric model was the correct model of the solar system; Johannes Kepler (1571–1630) formulated the laws of planetary motion that described the behavior of planets in the heliocentric model; and Isaac Newton (1642–1727) formulated the Laws of Motion and the Law of Universal Gravitation, which explained why the heliocentric model works.