High Quality Content by WIKIPEDIA articles! De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) is the seminal work on the heliocentric theory of the Renaissance astronomer Nicolaus Copernicus (1473–1543). The book, first printed in 1543 in Nuremberg, Holy Roman Empire of the German Nation, offered an alternative model of the universe to Ptolemy`s geocentric system, which had been widely accepted since ancient times.