Polish astronomer who suggested that the sun was the center is

Nicolaus Copernicus is the correct answer.

Explanation:

Nicolaus Copernicus developed a heliocentric model that states that the sun is a center position of the solar system and earth revolves around the sun.

Nicolaus Copernicus was called as a father of the modern astronomy

He proves that every planet including the moon, earth, and stars rotates around the sun,