The first early astronomer to propose a sun-centered solar system was

Nicolaus Copernicus

Explanation:

Nicolaus Copernicus was the first early astronomer to propose a sun-centered solar system. He was the one to first stated that the sun was at the center of the universe, this theory is called heliocentrism. Heliocentric model is the astronomical theory in which the Earth and the other planets revolve around the Sun at the center of the solar system.