The Apex of Ptolemaic Astronomy: the Epitome Almagesti of Peurbach and Regiomontanus
Lecture by Henry Zepeda
Given at the University of Missouri-Kansas City on July 30, 2019
Abstract: One of the treasures of the Linda Hall Library is a relatively thin, unassuming volume printed in Venice in 1496, entitled Epytoma in Almagestum Ptolemei. This book, a reworking of Ptolemy’s astronomical masterpiece, the Almagest, was written in the early 1460s by Georg Peurbach and Johannes Regiomontanus, two of the most important figures of fifteenth-century astronomy. While it built upon earlier medieval commentaries on the Almagest, the Epitome Almagesti (as it is usually called) is remarkable for its depth of comprehension of even the most technical aspects of Ptolemy’s astronomy, its clear explanations, and its incorporation of new discoveries made by its authors and by Arabic astronomers. This work, which had circulated in manuscript form for 35 years before it was printed, became the textbook by which students of astronomy learned the intricacies of Ptolemy’s geocentric astronomy.
In his writings challenging the Ptolemaic system, Copernicus did not always use Ptolemy’s own work, the Almagest; instead, he often referred to this book by Peurbach and Regiomontanus. Indeed, the Epitome Almagesti did not just serve as the foil to Copernicus’s new theories; on the contrary, it contained proofs that were fundamental to his development of a heliocentric system.
Dr. Zepeda will tell the drama-filled story of how and why this book was written, as well as discuss its contents, its sources, and its influence upon the astronomy of the 15th and 16th centuries.
Henry Zepeda is a historian of science with his specialization in the medieval mathematical sciences, especially astronomy. He is a Teaching Fellow at Wyoming Catholic College. .