The Opus Maius (1267) of the Franciscan Roger Bacon (d 1292), written at the request of Pope Clement IV, largely initiated the tradition of optics in the Latin world. The first spectacles were invented in Italy around 1300, an application of lenses that developed later into telescopes and microscopes. While many people think of Galileo (d 1642) being persecuted, they tend to forget the peculiar circumstances of these events, or the fact that he died in his bed and his daughter became a nun. The Gregorian Calendar (1582), now used worldwide, is a fruit of work by Catholic astronomers, as is the development of astrophysics by the spectroscopy of Fr Angelo Secchi (d 1878).
Most remarkably, the most important theory of modern cosmology, the Big Bang, was invented by a Catholic priest, Fr Georges Lemaître (d 1966, pictured), a historical fact that is almost never mentioned by the BBC or in popular science books.