Johannes Kepler (1571-1630)

Kepler approached astronomy through mysticism and remained through mathematics. Initially believing planets traveled perfect circles, he examined Tycho Brahe's unprecedented observational data and recognized circles didn't match reality.

Eight years of calculation revealed the answer: ellipses with the Sun at one focus. This discovery demolished two millennia of astronomical assumptions instantly. His three planetary motion laws, published 1609-1619, described not just orbital shapes but relationships between distance and period with unprecedented precision. Newton later read Kepler carefully - universal gravitation partially explained why Kepler's laws worked. He persevered through war, plague, his mother's witchcraft trial, and chronic poverty. Death came in 1630, having fundamentally altered humanity's understanding of its solar system position. His mathematical, orderly universe remains ours.