Who proposed the heliocentric model in the 16th century?

Nicolaus Copernicus proposed the heliocentric model in the 16th century. His model placed the Sun near the center of the planetary system and treated Earth as a moving planet that rotates on its axis and revolves around the Sun. This challenged the dominant Ptolemaic system, which placed a stationary Earth at the center of the cosmos.

Copernicus developed his ideas during the Renaissance and circulated an early outline, the Commentariolus, before completing his major book. He hesitated to publish the full theory, partly because it contradicted established astronomical and philosophical assumptions. His work was finally printed in 1543, the year of his death.

Copernicus did not invent the idea that the Sun might be central. The ancient Greek thinker Aristarchus of Samos had proposed an earlier Sun-centered model. Copernicus is nevertheless the canonical answer to this question because he formulated the influential 16th-century model that helped launch the Scientific Revolution. Galileo and Kepler later supplied important observational and mathematical support.