Johannes Kepler needed Tycho Brahe's data to formulate his laws of planetary motion because Brahe's observations were the most accurate and precise astronomical data available at the time. Kepler relied on these meticulous measurements, especially of Mars' orbit, to analyze planetary motion mathematically and ultimately discover that planets travel in elliptical orbits rather than perfect circles. Without Brahe's detailed records, Kepler would not have had the reliable empirical data required to derive his three fundamental laws that accurately describe planetary orbits. Brahe's data provided the essential observational foundation for Kepler's theoretical breakthroughs that marked a major advancement in astronomy and the understanding of the solar system.