Primarily, Nicolaus Copernicus formulated the model of the universe that it was the sun, placed at the center of the universe, rather than the Earth. It is widely accepted nowadays because of the reason that modern scientific discoveries proved that the Earth and other planets revolved around the Sun. Though the Sun is not the center of the universe, but it is the center of the solar system.
Before Copernicus introduced this model, people in the past long believed and accepted the model that the Earth was the center of all so it was hard for the people to immediately accept his model.