Copernicanism

Copernicanism refers to the model of the universe that places the Sun, rather than the Earth, at its center. This heliocentric model was famously articulated by Nicolaus Copernicus in his book "De revolutionibus orbium coelestium" (On the Revolutions of the Heavenly Spheres), published posthumously in 1543. Before Copernicus, the prevailing cosmological view was geocentric, largely based on the work of Ptolemy, which posited the Earth as stationary at the center of the universe with all celestial bodies revolving around it.

Copernicus's model suggested that the Earth rotated on its axis daily and orbited the Sun annually. This simplification explained the apparent retrograde motion of planets more elegantly than the complex epicycles used in the Ptolemaic system. While Copernicus's model was still imperfect, containing some elements of the older geocentric system such as circular orbits, it represented a radical departure and a significant step towards modern astronomy. The acceptance of Copernicanism was a gradual process, facing initial resistance from religious and scientific authorities. However, it laid the groundwork for the astronomical discoveries of later scientists like Johannes Kepler, Galileo Galilei, and Isaac Newton, who further refined and validated the heliocentric view. The shift from geocentrism to heliocentrism is often referred to as the Copernican Revolution.