Heliocentrism is a model of the universe which put the Sun in the center devised mathematically by Nicolaus Copernicus. This model replaced geocentrism, which placed the Earth at the center.
Aristotle was a Greek philosopher who first put forward the idea that Earth was at the center of the universe. This theory about the organization of the universe was the accepted model for thousands of years. The geocentric model was so widely accepted as it easily explained the apparent motion of the Sun and Moon around the Earth. The first evidence of somebody putting forward an alternative, Sun-centered model was by Aristarchus of Samos in around 300 BC. In the 16th century, a mathematical model of a heliocentric universe was created by Polish scientist and astronomer Nicolaus Copernicus.
The heliocentric model gained important empirical support when Galileo was surveying the night sky with the newly invented telescope. He noticed four objects near Jupiter. Over a few days he observed that these objects were not stationary, but were in fact orbiting around the planet. Galileo showed that the geocentric model couldn’t be correct if there were celestial bodies orbiting something other than the Earth. This idea and the observations that supported it ended up with Galileo being placed under house arrest because his discoveries didn’t agree with the teachings of the Catholic Church.
The realization that Earth was not the center of the universe opened up other astronomical investigations, leading to the discoveries of galaxies, other stars, and more. Even though the Sun is not the center of the entire universe, it is the center of our Solar System.