In Galileos lifetime, all celestial bodies were thought to orbit the Earth. Supported by the Catholic Church, teaching opposite of this system was declared heresy in 1615.Galileo, however, did not agree. His research including his observations of the phases of Venus and the fact that Jupiter boasted moons that didnt orbit Earth supported the Copernican system, which (correctly) stated that the Earth and other planets circle the sun.In 1616, he was summoned to Rome and warned not to teach or write about this controversial theory. But in 1632, believing that he could write on the subject if he treated it as a mathematical proposition, he published work on the Copernican system. He was found guilty of heresy, and was placed under house arrest for the remaining nine years of his life.