The Harmonice Mundi was Kepler's last major original contribution, but he continued to publish important works for the rest of his life. In 1619, he published the Epitome Astronomiae Copernicae, a description of the universe. It was basically an updated view of the Copernican system, with all Kepler's planetary laws incorporated. This was the first astronomy textbook to use a heliocentric system, and it is the first complete appearance of the simplified system now associated with Copernicus – the Keplerian universe.
In 1627, Kepler published the Tabulae Rudolphinae, or the Rudolphine Tables. These tables were an extensive list of observations, predictions, and explanations that had been a tedious nightmare for Kepler to compile. For over one hundred years, scientists and navigators used them to calculate the positions of the stars and planets.
The publication of the Tabulae Rudolphinae marked the beginning of the end for Kepler. During the publication process, he left Linz forever. Thanks to increasing religious persecution and a series of peasant revolts, life there had become intolerable. Kepler, who all his life had considered himself a nomad in exile, now began his final wanderings. Left with no home to return to, he traveled aimlessly around the region, leaving a number of rejected job offers in his wake. After months of this wandering, he contracted a fever. He died two weeks later, on November 15, 1630.
Kepler is one of the more complicated figures in the history of science, and he is largely overlooked by historians. Books about the Scientific Revolution often devote only a few pages to Kepler's innovations, and the few biographies on his life hardly compare to the multitude of books about Copernicus, Galileo, and Newton.
Kepler is a mess of contradictions that mirror the confusion of his transitional era. His love of astronomy was combined with a hidden passion for astronomy; his best scientific work was sprinkled with wild ideas about magical solids and heavenly harmonies. Even his most fundamental scientific contributions – his planetary laws – were discovered only because he felt driven to confirm his spiritual inspirations about the structure of the universe. On the other hand, although Kepler believed firmly in a divinely constructed universe, he was one of the first to attempt a fully mechanized system that could operate without the Divine influence.
It is difficult to fully explain the effect he had on his field. Kepler's achievements were not obvious, and his mistakes were many. Even Kepler did not fully appreciate the value of his own work – he always valued his theories of the perfect solids and harmonic ratios far more than his three laws.
But more important than Kepler's many wrong answers is the fact that he asked so many right questions. This ranting mystic was also one of the most modern scientific thinkers of his time. He challenged the common wisdom of the preceding millennia that astronomy's goal was to create geometrical models of planetary motion. Instead, Kepler insisted that astronomy should be a physical science, concerned with the actual motion of planetary bodies. Thus he rejoined astronomy and physics, which had been separated for centuries.
Kepler lived and worked at a turning point in the age of astronomy. His love of philosophy, astrology, mysticism, and religion, and his passion for divine aesthetics of the universe made him one of the last great astronomers of the past. But his devotion to accuracy, his endless questioning, and his unification of astronomy and physics marked him as one of the first great astronomers of the modern era.