Kepler Fest: Reversing the Notion of Circular Motion

February 10, 2017 | By Andrew Wice

Bill Donohue holds a transcript
William Donahue holds a facsimile of Kepler’s original manuscript.

Astronomer Johannes Kepler, whose achievements revolutionized astronomy, will star in his own festival February 17-18 at the Santa Fe campus of St. John’s College.

The free series of events, dubbed “Kepler Fest,” will include lectures, workshops, art and music.

In addition to exploring the work of Kepler (1571-1630), whose scientific texts are part of the St. John’s great books program, Kepler Fest celebrates a newly retranslated and revised edition of Kepler’s landmark book, Astronomia Nova, authored by tutor emeritus William Donahue. The book examined the bedrock assumption of 2,000 years of ancient astronomy—an idealized geometry of uniform, circular orbits—and unceremoniously discarded it. Kepler demonstrated that orbits are elliptical, with varying speed. More than simply a breakthrough in astronomy, Astronomia Nova represented a new, physics-based methodology which lit the path for all the scientists who followed.

Sophomores at St. John’s in Santa Fe have the opportunity to make this discovery themselves when they read Donahue’s translation of Kepler’s masterpiece.

“In trying to understand Kepler or Newton or Plato or Hegel or whoever, I try to stay out of the student’s way as much as possible,” Donahue says. “It can be stultifying to have someone who knows the book so well. … The students are reading the original text themselves, it’s wonderfully empowering. They realize, ‘This was written by another human being trying to communicate to me.’”

Donahue has updated his original translation of Kepler’s 1609 masterpiece. The tome, published by Green Lion Press in 2015, introduces all-new diagrams, tables, a comprehensive index and a catalog of the original observations. These features allow readers to work through Kepler’s calculations. This new edition is the only in-print English translation of Kepler’s masterpiece which is, along with Copernicus’s De Revolutionibus and Newton’s Principia, one of the foundational scientific texts of the Age of Reason.