Galileo Galilei

Galileo Galilei (1564–1642) was an Italian astronomer, physicist and mathematician. He taught mathematics at Pisa and Padua from 1589 to 1610. In 1609, after hearing of the Dutch spyglass, he built a telescope, and in January 1610 he discovered four moons circling Jupiter, named them the Medicean stars and reported them in his Starry Messenger, and saw Venus's phases, which favoured Copernicus.

In 1616 an Inquisitorial commission declared heliocentrism formally heretical. When his friend Maffeo Barberini became Pope Urban VIII in 1623, he took up the subject again, and his Dialogue of 1632 made its Aristotelian speaker look a fool, seeming to mock the pope.

Summoned to Rome, he was tried in 1633, forced to recant and sentenced to life house arrest. At Arcetri he wrote Two New Sciences (1638) and he died on 8 January 1642. In 1992 Pope John Paul II acknowledged that the Inquisition had erred.