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. The idea of heliocentrism was popularized by Nicolaus Copernicus in the 16th century, challenging long-held beliefs. Later, astronomers like Galileo Galilei and Johannes Kepler provided further evidence and refined the model, leading to a better understanding of planetary motion and the structure of our solar system.