Who first theorized that the planets revolve around the sun?

The first person to theorize that the planets revolve around the sun was Aristarchus of Samos, a Greek astronomer and mathematician who lived in the third century B.C. His theory conflicted with the dominant geocentric models of the time, and it was not widely accepted.

In the 16th century, Nicolaus Copernicus revisited the concept of the heliocentric solar system and used it as the basis for a mathematical model of the heavens. His work proved revolutionary, and it redefined scientific understanding of astronomy. His work triggered a massive conflict with the Catholic church, which held strongly to the geocentric model of the universe.