De revolutionibus orbium coelestium
De revolutionibus orbium coelestium (; English translation: "On the Revolutions of the Heavenly Spheres") is the seminal work on the heliocentric theory of the astronomer Nicolaus Copernicus (1473–1543) of the Polish Renaissance. The book, first printed in 1543 in Nuremberg, Holy Roman Empire, offered an alternative model of the universe to Ptolemy's geocentric system, which had been widely accepted since ancient times.