Final answer:
Galileo Galilei was the central figure in the controversy between the Catholic Church and the Copernicans due to his strong advocacy for the heliocentric theory proposed by Nicolaus Copernicus.
Step-by-step explanation:
The lightning rod in the controversy between the Catholic Church and the Copernicans was Galileo Galilei. During the 1590s, Galileo adopted the heliocentric hypothesis proposed by Nicolaus Copernicus, which placed the Sun at the center of the universe instead of the Earth. This position directly opposed the geocentric view held by the Church. Galileo's enthusiastic advocacy for the Copernican theory, alongside his public lectures and Italian writings—which were more accessible than scholarly Latin—brought significant attention and, ultimately, led to his confrontation with the Church. The church labeled the doctrine as 'false and absurd' and prohibited its teaching. Galileo was accused of heresy and was ultimately placed under house arrest for his beliefs, thus making him a notable figure in the pursuit of scientific truth against religious dogma.