February 16: Georg Joachim Rheticus

Georg Joachim Rheticus

February 16, 1514 – December 4 1574

Georg Joachim von Lauchen, also known as Rheticus, was a mathematician, cartographer, navigational and other instrument maker, medical practitioner, and teacher. He is perhaps best known for his trigonometric tables, and for being the only pupil of Nicolaus Copernicus, facilitating the major publication of his De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres).

In 1536 Rheticus was aided by Philipp Melanchthon in obtaining appointment to a teaching position in astronomy and mathematics at Wittenberg University. Two years later, Melanchthon arranged a two year leave for Rheticus in order to study with noted astronomers of the day. Rheticus took this opportunity to visit Copernicus in Frombork (Frauenburg). Leaving Wittenberg in October 1538, he first went to Nuremberg to visit the publisher Johannes Schöner and the printer Petreius. Here, Rheticus was given works of Regiomontanus and others, intended as presents to Copernicus. He proceeded on to Peter Apian in Ingolstadt and Joachim Camerarius in Tübingen, then to Achilles Gasser in his hometown.

In May 1539 he arrived in Frombork (Frauenburg) and spent two years there with Copernicus. It is unknown whether he had prior direct access to Copernicus' Commentariolus, and if so, since when. Copernicus had outlined his revolutionary heliocentric theory of the solar system three decades earlier, but handed out only few copies to friends.

In September 1539 Rheticus went to Danzig (Gdańsk) to visited the mayor who gave Rheticus some financial assistance to publish the First Report or Narratio Prima. This Narratio Prima, published by Rhode in Danzig in 1540, is still considered to be the best introduction to Copernicus' De revolutionibus orbium coelestium. 

In August 1541 Rheticus presented a copy of his work Tabula chorographica auff Preussen und etliche umbliegende lender (Map of Prussia and Neighboring Lands) to Duke Albrecht of Prussia who had been trying to compute the exact time of sunrise. Rheticus made an instrument for him that determined the length of the day. Rheticus asked and received the permission of the duke for the publication of the Copernicus De revolutionibus. Albrecht requested of Rheticus that he return to his teaching position. He returned to the University of Wittenberg in October 1541, after earlier publishing the trigonometrical sections of the Copernicus De revolutionibus. In 1542 he traveled to Nürnberg to supervise the printing of the Copernicus material by Johannes Petreius, published upon Copernicus' death in 1543.

The crater Rhaeticus was named in his honor.