Miracles and science: Santa Maria delle Carceri in Prato
The Church of Santa Maria delle Carceri was built in 1485 as protection for a venerated image of the Virgin, which, starting from July 6, 1484, had been the font of miraculous apparitions. The project, originally commissioned of Giuliano da Maiano (1432-1490), was then carried out by Giuliano da Sangallo (1445-1516) with extraordinary attention to the orientation of the building, obviously for the purpose of ensuring selective lighting of the miraculous image. Exactly on the day of the miracle, and just at the hour in which the chronicles report the occurrence of the first apparition – at 3:18 p.m. (2:03 solar time) on July 15 (July 6 according to the Julian calendar) – a disk of light suddenly appears at the center of the altar, remains there a few minutes, and then disappears toward the lower right. On the day of the summer solstice, instead, June 21, when the azimuth of the Sun coincides with the main axis of the church (221°), a beam of light falls from the windows in the lantern, perfectly centering the fresco of the Virgin.