Nicholaus Copernicus (1473-1543)
Nicholaus Copernicus was a priest and astronomer. He was the first person to discover that the Earth revolved around the sun, contrary to belief during his time that the earth was the center of the universe.
Being a priest, Copernicus was not open about his theory as his theory was a contradiction to the church's teachings at that time. When Copernicus was in his last days, a friend managed to convince him to publish his works. His book "On The Revolutions Of The Celestial Spheres" was published before his death.
Copernicus's theory (Heliocentric Cosmology) was considered impossible by most of the people, philosophers and fellow astronomers during his time and many decades after that. There was simply insufficient evidence to prove to all the people his theory. His works became the basis for Kepler, Galileo and Newton. It is an understatement to say that Copernicus is an important figure in astrology.