Nicolaus Copernicus (February 19, 1473 - May 24, 1543) was the first astronomer to formulate a scientifically based heliocentric cosmology that displaced the Earth from the center of the universe. His epochal book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), is often regarded as the starting point of modern astronomy and the defining epiphany that began the Scientific Revolution.