Nicolaus Copernicus

Nicolaus Copernicus initiated the Copernican Revolution by proposing a heliocentric model of the universe in his seminal work 'De revolutionibus orbium coelestium' (1543). Displacing Earth from the center of the cosmos was a profound psychological and scientific shock, challenging over a millennium of Ptolemaic geocentric astronomy and Aristotelian physics. While his system was complex and still used circular orbits, its central premise—that the Sun, not the Earth, was at the center—was revolutionary. This single idea provided a simpler explanation for retrograde planetary motion and reordered humanity's place in the cosmos.

It set the stage for the work of Kepler, Galileo, and Newton, marking the definitive beginning of modern astronomy and the Scientific Revolution.