Who was the only student of Copernicus to publish his heliocentric ideas before De revolutionibus?

The only student of Copernicus to publish his heliocentric ideas before De revolutionibus was Georg Joachim Rheticus. A mathematician and astronomer from Feldkirch, Rheticus visited Copernicus in 1539 and became his only known pupil.

Rheticus quickly understood the importance of Copernicus’s unpublished manuscript. In 1540, he published Narratio Prima, an accessible summary of Copernicus’s heliocentric theory. It was the first printed publication of the Copernican system and appeared three years before Copernicus’s major work, De revolutionibus orbium coelestium, was printed in 1543.

Rheticus’s publication did more than announce the theory. Its favorable reception helped persuade the cautious, elderly Copernicus to allow De revolutionibus to go to press. Rheticus also helped prepare the work for publication and supervised part of its printing, although Andreas Osiander later inserted an anonymous preface presenting the heliocentric system as a mathematical hypothesis.

A common mix-up is to treat other early supporters of heliocentrism as Copernicus’s students. Thomas Digges popularized Copernican ideas in England later in the sixteenth century, while Michael Maestlin influenced Johannes Kepler. Neither was Copernicus’s pupil, and neither published Copernicus’s theory before Narratio Prima.