Sancte Pater has the skinny from Thomas Woods, Jr.:
“The Italian astronomer Giovanni Cassini, a student of the Jesuits Riccioloi and Grimaldi, used the observatory at the splendid Basilica of San Petronio in Bologna to lend support to Kepler’s model.
“Here we see an important way in which the Church contributed to astronomy that is all but unknown today: Cathedrals in Bologna, Florence, Paris and Rome were designed in the seventeenth and eighteenth centuries to function as world-class solar observatories. Nowhere in the world were there more precise instruments for the study of the sun. Each such cathedral contained holes through which sunlight could enter and time lines (or meridian lines) on the floor. It was by observing the path traced out by the sunlight on these lines that researchers could obtain accurate measurements of time and predict equinoxes. (They could also make accurate calculations of the proper dates for Easter — the key initial function of these observatories.)”