Copernicus, Nicolaus, Latin name of Mikojaj Kopernik 1473-1543
Polish astronomer

Copernicus was born in Tor�n in Prussia (now in Poland). He was brought up after his father's death (1483) by his uncle, later Bishop of Ermeland. After studying mathematics at the University of Cracow (1491-94) he went to Italy (1496) where he studied canon law and heard lectures on astronomy at the University of Bologna, while at Padua he studied medicine (1501-05). He was made a Doctor of Canon Law by the University of Ferrara (1503), and though nominated a canon at the cathedral of Frombork (1497), he never took holy orders.

On his return to Poland, he became his uncle's medical adviser and undertook administrative duties at Frombork, where he spent the rest of his life. He pondered deeply on what he considered the unsatisfactory description of the world by Ptolemy, which had the Earth as the stationary centre of the universe, and became converted to the idea of a Sun-centred universe. He set out to describe this mathematically in 1512. Copernicus hesitated to make his work public, having no wish to draw criticism from Aristotelian traditionalists or from theologians such as Martin Luther who had ridiculed him, but was eventually persuaded by his disciple Rheticus to publish his complete work, De Revolutionibus Orbium Coelestium (1543, 'The Revolutions of the Celestial Spheres'), which he dedicated to Pope Paul III.

In the new system, the Earth is merely one of the planets, revolving around the Sun and rotating on its axis. The absence of any apparent movement of the stars caused by the Earth's annual motion was interpreted as due to the great size of the sphere of the stars. The transfer of the centre of the system from the Earth to the Sun in the new arrangement greatly simplified the geometry of the planetary system, though it did not dispense with all the epicycles of Ptolemy's model, a step which had to await Johannes Kepler.

Copernicus was already old and ill by the time his book was printed, and he was unaware that it carried an anonymous and unauthorized 'Preface to the Reader', presenting the work as a hypothesis rather than a true physical reality, written by Andreas Osiander (1498-1552), a Lutheran pastor of Nuremberg who supervised the last stages of the printing. Osiander's misguided intention was to forestall criticism of the heliocentric theory. The first printed copy of Copernicus's treatise, a work which fundamentally altered man's vision of the universe, reached its author on his death bed. It was later banned by the Catholic Church, and remained on the list of forbidden books until 1835.

Bibliography: John Banville, Doctor Copernicus (1977); Jan Adamczewski and Edward J Piszek, Nicolaus Copernicus and His Epoch (1974); Thomas S Kuhn, The Copernican Revolution (1957); Angus Armitage, Sun, Stand Thou Still (1947, rev edn The World of Copernicus, 1956).