Nicolaus Copernicus

Nicolaus Copernicus placed the sun rather than the earth at the centre of the known universe, and delayed publishing the claim for most of his adult life. Born in Toruń in 1473 in Royal Prussia, part of the Kingdom of Poland, he was orphaned at ten and raised by an uncle who became Bishop of Warmia and secured his education. He studied astronomy at Kraków, canon law at Bologna, and medicine at Padua, and took a doctorate in canon law at Ferrara in 1503. He spent the rest of his life as a canon of Frombork cathedral — administering estates, practising medicine, and serving as a diplomat during the Polish-Teutonic war. He was not a professional astronomer, and his observations were relatively few. Around 1514 he circulated a handwritten summary, the Commentariolus, setting out the heliocentric hypothesis to a small circle. In 1517 he wrote on currency debasement, formulating what became known as Gresham's law a generation before Gresham. De revolutionibus orbium coelestium was published in 1543, reportedly reaching him on his deathbed. Its argument was that the apparent motion of the heavens follows more simply if the earth rotates daily and orbits the sun annually. He retained perfectly circular orbits and so still needed epicycles, which meant his system was no more accurate at prediction than Ptolemy's — the case for it rested on coherence rather than precision. Kepler's ellipses in 1609 supplied what was missing. The book carried an unsigned preface by Andreas Osiander presenting the theory as a calculating device rather than a claim about reality, which softened its reception. The Church placed it on the Index only in 1616, during Galileo's dispute, seventy-three years after publication.

• Lived: 1473 CE – 1543 CE
• Nationality: Polish
• Roles: astronomer, mathematician, physician, catholic_canon