text: Nicolaus Copernicus (February 19, 1473 – May 24, 1543) was an astronomer who provided the first modern formulation of a heliocentric (sun-centered) theory of the solar system in his epochal book, De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres). Copernicus was born in 1473 in the city of Toruń (Thorn), in Royal Prussia, an autonomous province of the Kingdom of Poland. He was educated in Poland and Italy, and spent most of his working life in Frombork (Frauenburg), Warmia, where he died in 1543.