Celestial Chat

Copernicus’s big idea may have sprouted from earlier talk among scholars.

No one, least of all UW-Madison’s Michael Shank, disputes that Polish astronomer Nicolaus Copernicus was responsible for displacing Earth with the Sun as the center of the universe. In the early sixteenth century, Copernicus was the first to explain mathematically the apparent motions of celestial objects sans a rock-steady Earth at the center of it all.

But was Copernicus’s big idea a singular inspiration, as most people believe, or the upshot of a longstanding scholarly conversation lost to the ages? Sages in ancient Greece, India, and the Muslim world had previously proposed and debated Earth’s motion, but it was the work of Copernicus, a polymath Catholic cleric who also studied mathematics, medicine, the military arts, economics, and law, that is widely regarded as the catalyst that sparked the scientific revolution.

“The old story is that Copernicus’s [heliocentric theory] is a bolt out of the blue,” says Shank, a professor of history of science. But in a paper in the journal , Shank suggests that Copernicus’s monumental (On the Revolution of the Heavenly Spheres) may have been a response to commentaries then circulating in late-medieval European universities. In particular, Shank cites the work of Francesco Capuano, a Padua teacher of astronomy and the mathematical sciences, and a contemporary of Copernicus.

In the late fifteenth and early sixteenth centuries, Shank says, Capuano and others were attacking “proto-Copernican arguments” about possible motions of Earth before Copernicus made sense of things using mathematics. Shank notes that little is known about the university context of Copernicus’s heliocentrism, adding, “The odd thing is no one’s really looked carefully at these commentaries.”

Shank explains that, in , Copernicus may well have been responding to Capuano’s commentary detailing the arguments against a movable Earth.

Published in the Fall 2009 issue