Nicolaus Copernicus was born on 19 February 1473 in Torun, in Royal Prussia, then part of the Kingdom of Poland, and studied canon law, medicine and astronomy across universities in Krakow, Bologna, Padua and Ferrara before returning to take up a lifelong position as canon of Frauenburg Cathedral, a Church administrative and clerical post he held alongside his astronomical work for the rest of his life. Copernicus was never ordained a priest in the fullest sense some later accounts assume, but he held holy orders sufficient to his canonry and lived his working life within the institutional Church rather than outside it.
He developed his heliocentric model, in which the Earth and other planets orbit the Sun rather than the reverse, as a private scholarly project over several decades, circulating an early sketch privately among a small circle of correspondents well before he committed to full publication. He delayed publishing the complete theory until the very end of his life, reportedly receiving a printed copy of De revolutionibus orbium coelestium only on the day he died, 24 May 1543, or very close to it.
Copernicus's canonry involved substantial administrative and even medical duties alongside his religious obligations, including managing diocesan estates and practicing medicine for fellow clergy, work that occupied much of his working life and that he balanced against the astronomical observations and calculations he pursued largely alone, without the institutional support of a university or royal patron a figure of his eventual historical importance might be expected to have had during his own lifetime.