The geocentric model is an ancient astronomical theory that places the Earth at the center of the universe. According to this model, all celestial bodies, including the Sun, Moon, and planets, revolve around the Earth in circular orbits. This view was widely accepted in many ancient cultures, including those of the Greeks and Romans. The geocentric model was most famously articulated by the astronomer Claudius Ptolemy in the 2nd century AD. It remained the dominant explanation of the cosmos until the Copernican Revolution in the 16th century, when the heliocentric model, which positions the Sun at the center, gained acceptance.