Giovanni Battista Riccioli, SJ (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion of 126 arguments concerning the motion of the Earth, and for introducing the current scheme of lunar nomenclature. He is also widely known for discovering the first double star. He argued that the rotation of the Earth should reveal itself because on a rotating Earth, the ground moves at different speeds at different times. Biography Riccioli was born in Ferrara. He entered the Society of Jesus on 6 October 1614. After completing his novitiate, he began to study humanities in 1616, pursuing those studies first at Ferrara, and then at Piacenza. From 1620 to 1628 he studied philosophy and theology at the College of Parma. Parma Jesuits had developed a strong program of experimentation, such as with falling bodies. One of the most famous Italian Jesuits of the time, Giuseppe Biancani (1565–1624), was teaching at Parma when Riccioli arrived there. Biancani accepted new astronomical ideas, such as the existence of lunar mountains and the fluid nature of the heavens, and collaborated with the Jesuit astronomer Christoph Scheiner (1573–1650) on sunspot observations. Riccioli mentions him with gratitude and admiration. By 1628 Riccioli's studies were complete and he was ordained. He requested missionary work, but that request was turned down. Instead, he was assigned to teach at Parma. There he taught logic, physics, and metaphysics from 1629 to 1632, and engaged in some experiments with falling bodies and pendulums. In 1632 he became a member of a group charged with the formation of younger Jesuits, among whom Daniello Bartoli. He spent the 1633–1634 academic year in Mantua, where he collaborated with Niccolò Cabeo (1576–1650) in further pendulum studies. In 1635 he was back at Parma, where he taught theology and also carried out his first important observation of the Moon. In 1636 he was sent to Bologna to serve as Professor of theology. Riccioli described himself as a theologian, but one with a strong and ongoing interest in astronomy since his student days, when he studied under Biancani. He said that many Jesuits were theologians, but few were astronomers. He said that once the enthusiasm for astronomy arose within him he could never extinguish it, and so he became more committed