Rheticus born Georg Joachim von Lauchen in Feldkirch, Austria, but, in the manner of the time, he adopted a professional name from the Latinized form of his birth district, Rhaetia. After traveling in Italy and after attending several German universities, Rheticus was appointed professor of mathematics at Wittenberg in 1536; the chair of astronomy at the time was held by Reinhold. Both were Copernicans and both knew that the doctrine was opposed by the authorities, Protestant and Catholic alike.

Nevertheless the Protestant Rheticus traveled to Catholic Poland in 1539 to see Copernicus. As it happened Copernicus had completed the manuscript of his De revolutionibus (On Revolutions) many years before but, for a number of reasons, was unwilling to publish the work. Rheticus was a man of some charm and consequently persuaded Copernicus to allow a brief summary of his work to appear. The result was the Narratio Prima of Rheticus (Danzig, 1539; Basel, 1541; The First Narrative of Rheticus). It caused no major reactions and consequently Copernicus released the manuscript of the De revolutionibus to Rheticus.

A brief stay of a few weeks was extended to two years as Rheticus first copied the manuscript and then prepared the text for publication. By May 1542 Rheticus was ready to take the manuscript to the Nuremberg printers. When the work finally appeared in 1543 Copernicus failed to acknowledge the help of Rheticus in any way at all.

By this time Rheticus, reportedly because of his homosexuality, was no longer acceptable at Wittenberg and moved accordingly to the Leipzig chair of mathematics in 1542. But in 1550 he was once more forced into flight charged with indulging in ‘Italian perversions’. Thereafter Rheticus seems to have practiced medicine and is occasionally met with in the service of some noble house.

During the latter part of his life Rheticus had, with the assistance of several calculators, prepared a massive set of trigonometrical tables. Whereas previous workers had expressed the functions in terms of arcs of circles, Rheticus introduced the modern practice of defining them as ratios between the sides of right triangles. Ten-place tables were computed for all six trigonometric functions for every 10ʺ of arc. The work was incomplete at his death and Rheticus needed his own disciple to publish his manuscript. It finally appeared in 1596 edited by Valentin Otho as the Opus palatinum de triangulis (The Imperial Work on Triangles).