Rheticus, Georg Joachim

Abstract

Rheticus (b. Feldkirch, 1514) in his early twenties became a professor at the University of Wittenberg, where Philipp Melanchthon declared he “was born to the study of mathematics.” In 1539, having heard rumors of a new sun-centered cosmology, he sought out the elderly, little-known astronomer Nicolaus Copernicus in Frauenburg (Frombork), remaining there for two and a half years. In 1540 Rheticus published his own first account (Narratio prima) of Copernicus’s cosmology, according to which earth is a planet rotating on its axis and revolving annually about a central sun. He later delivered Copernicus’s manuscript of De revolutionibus to Nuremberg, where it was published in 1543.

After the death of Copernicus, Rheticus served as the “apostle” of heliocentrism, developing mathematical tools to aid its hoped-for confirmation. His 1551 Canon doctrinae triangulorum contained the first tables of all six trigonometric functions, and his much larger (posthumous) Opus Palatinum de Triangulis (1596) fathered generations of trig tables not superseded until the twentieth century.

Rheticus’s impact was principally in astronomy and in closely related areas of mathematics. His theologically grounded belief in “God’s geometry in heaven and on earth” supported his realism about the philosophical truth status of Copernicanism and a rejection of the instrumentalism according to which astronomy’s claims (in Andreas Osiander’s words) “need not be true nor even probable.”