In 1543, Polish astronomer Nicolaus Copernicus published *De revolutionibus orbium coelestium* (*On the Revolutions of the Celestial Spheres*), proposing that the Sun — not the Earth — stood at the centre of the universe. The work appeared the same year Copernicus died, reportedly on the day printed copies arrived.
The heliocentric model challenged over a millennium of Ptolemaic geocentric astronomy and the theological authority of the Church, which taught that humanity's home was the cosmos's pivot. The Church placed *De revolutionibus* on its Index of Forbidden Books in 1616, but the theory had already taken root.
Copernicus's ideas were extended by Tycho Brahe's observations, confirmed by Galileo's telescope, given mathematical rigour by Johannes Kepler, and unified with terrestrial physics by Isaac Newton. The "Copernican Revolution" became a byword for any paradigm shift that fundamentally overturns a prevailing worldview.