Copernicus, Tycho Brahe, and Kepler: The New Astronomy

Nicolaus Copernicus published De revolutionibus orbium coelestium in 1543, the very year of his death, proposing a heliocentric model in which the Sun, not the Earth, occupied the center of the known universe — a direct challenge to the Ptolemaic geocentric system that had dominated astronomy for more than 1,400 years. Copernicus, a Polish ecclesiastical canon who had studied at Kraków, Bologna, and Padua, still clung to one piece of Greek inheritance, retaining the idea of perfectly circular orbits, and to soften the theory's reception an anonymous preface by Andreas Osiander presented it merely as a convenient mathematical hypothesis rather than a physical truth. His ideas had already circulated in a manuscript, the Commentariolus, around 1514, and it was his disciple Georg Joachim Rheticus who was decisive in persuading him to publish and in preparing the final manuscript for the press. Early resistance came from Aristotelian astronomers and from theologians, including Martin Luther, who considered heliocentrism contrary to Scripture, and in 1616 the Catholic Church placed the work on the Index of Forbidden Books, requiring specific corrections rather than an outright ban.