Final answer:
Johannes Kepler was Tycho Brahe's assistant who published Brahe's astronomical data after his death. Kepler's work laid the mathematical foundation for the heliocentric model of the cosmos.
Step-by-step explanation:
Tycho Brahe was a preeminent astronomer renowned for his precise measurements of celestial bodies without the aid of a telescope. His meticulous observations, especially from his observatory on the island of Hven, challenged existing astronomical models. However, Brahe was not equipped to synthesize a new model from his extensive astronomical data. It was Johannes Kepler, Brahe's assistant and scientific heir in Prague, who succeeded in publishing Brahe's data posthumously. Kepler's work not only honored Brahe's legacy but also revolutionized our understanding of the cosmos by discovering the fundamental laws of planetary motion, thus substantiating the heliocentric model of Copernicus.