The sun in the church. Cathedrals as solar observatories (Q2715818)

In this learned, elegant and finely phrased book, illustrated with beautiful copper plates, John Heilbron shows that in the seventeenth and eighteenth centuries, several of the major Catholic cathedrals served as precision instruments for studying the motion of the sun. Built with the aim to determine the exact time between equinoxes in order to forecast the dates for Easter, these churches were used as giant sundials for astronomical measurement. In this context, astronomy was a science of central importance in Italy, and contrary to common views about the Church's relationship to science after Galileo's trial, we learn that Rome strongly supported astronomical studies, even accepting the Copernican hypothesis as a fiction that was useful for calculation.