Nicolaus Copernicus

Nicolaus Copernicus was a Renaissance polymath — a mathematician, astronomer, physician, classical scholar, translator, governor, diplomat, and economist. Born in Royal Prussia, he studied at the universities of Krakow, Bologna, and Padua. His revolutionary work De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), published just before his death in 1543, proposed that the Sun, not the Earth, was the center of the universe. This heliocentric model elegantly explained the retrograde motion of planets and simplified the complex system of epicycles that Ptolemy's model required. Although the Copernican model still used circular orbits (and thus still needed some epicycles), it fundamentally changed humanity's understanding of its place in the cosmos. The "Copernican Revolution" became a metaphor for any paradigm-shifting change in worldview.

Proposed the heliocentric (Sun-centered) model of the solar system in De revolutionibus. Correctly ordered the six known planets by distance from the Sun. Explained planetary retrograde motion as a natural consequence of Earth's own orbital motion. Calculated the relative distances of planets from the Sun with reasonable accuracy. Sparked the Scientific Revolution and inspired Kepler, Galileo, and Newton.