The correct answer is - Nicolaus Copernicus.
Nicolaus Copernicus was the man that proposed and promoted the heliocentric theory about the Solar System. He was a man that was very knowledgeable, and also wanted to experiment and research, with the biggest interest in mathematics and astronomy, which was not a common thing for a Catholic cleric in that period of time.
Copernicus's heliocentric theory suggested that it is not the Earth that is the center of the universe and everything revolves around it, but instead, it was the Sun that was the center and everything, including the Earth revolved around it.
Unfortunately, Copernicus did not had a solid prove about this, so the theory was accepted after Galileo Galilei managed to bring in proof to the public with his telescope.