* Nicolaus Copernicus (1473-1543): A Polish astronomer who revolutionized our understanding of the universe with his heliocentric model, placing the Sun at the center of the solar system, not the Earth. His groundbreaking work, *De Revolutionibus Orbium Coelestium* (On the Revolutions of the Heavenly Spheres), was published shortly before his death and became a cornerstone of the scientific revolution.

* Tycho Brahe (1546-1601): A Danish astronomer known for his precise and extensive astronomical observations. He meticulously recorded the positions of stars and planets, which became invaluable data for later astronomers like Johannes Kepler. Though he was a staunch defender of a geocentric model, his meticulous observations helped to eventually disprove it.

While Copernicus's theoretical work laid the groundwork for a new understanding of the universe, Brahe's empirical data proved crucial for later scientists to build upon and ultimately confirm the heliocentric model.