The Sun in the Church

In "The Sun in the Church", J. L. Heilbron describes the practical problem that faced the Church, in determining when Easter should be celebrated (the first Sunday after the first full moon after the vernal equinox) and how it supported research to resolve that matter (and also the problem of a church year that didn't match the solar one) without quite conceding that the earth orbits the sun. In the 1570's, Egnatio Danti began the work that would be culminated nearly 100 years later by Giovanni Domenico Cassini, in which the cathedral San Petronio was turned into a kind of solar observatory by knocking a hole in the roof and laying a precise meridian line into the floor. Ultimately, of course, the project compiled overwhelming evidence that Copernicus, Galileo, and Kepler were correct. Heilbron does an outstanding job of describing the scientific challenges and their resolution. The fine periodical, "The Sciences" has been discontinued by the New York Academy of Sciences, but the archives are available (free) on the Web.

Pick Attribution: 

J. L. Heilbron

Publication Date: 
Friday, April 13, 2012