Answer:
He insisted that the sun was at the center of the universe.
Step-by-step explanation:
Nicolaus Copernicus who was initially a church administrator was later known for his astronomical studies. Contrary to ancient philosophers and early European scientists that planet Earth is at the center of the universe. Copernicus, in 1543 concluded that Sun is at the center of the Universe, whereby the Earth rotates around the Sun, instead of the Sun rotating around the Earth.
He also concluded that Earth moves about every day on its axis and this leads to changing seasons.