1-153-661 - Ann Ronan Picture Library/Heritage-Images

Title page of Copernicus' De revolutionibus orbium coelestium, 1543. Polish astronomer Nicolaus Copernicus (1473-1543) is considered to be the father of modern astronomy and founder of heliocentric cosmology. Prior to his work, the Earth was considered to be the stationary centre of the universe, a notion first advocated by the Egyptian astronomer Ptolemy. Copernicus' pioneering work De revolutionibus orbium coelestium (The Revolutions of Celestial Spheres) (Nuremberg, 1543) describes his idea of a Sun-centred universe, in which the Earth is merely one of the planets revolving around the Sun and rotating on its axis.