Heliocentrism is the astronomical model that places the Sun at the center of the Solar System, with the Earth and other planets orbiting around it. This concept contrasts with the earlier geocentric model, which suggested that the Earth was the center of the universe. Heliocentrism was first proposed by Nicolaus Copernicus in the 16th century and later supported by observations from astronomers like Galileo Galilei. The acceptance of heliocentrism marked a significant shift in scientific thought, leading to the Copernican Revolution. This change laid the groundwork for modern astronomy and our understanding of the universe. Heliocentrism helped explain the apparent retrograde motion of planets and provided a more accurate model of planetary motion.