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Johannes Kepler

Johannes Kepler


Portrait by Hans von Aachen. Wikimedia, Public Domain

We’ve finished our 2015 tour of the solar system – been to all the planets, including our own, and even stopped at the Moon in October. But we have one month to go. What to do? In truth, I rejected the many ways to stretch the coverage and decided on a December topic months ago. Question: who unlocked the door to our modern understanding of this planetary system? In my opinion, one person did.


I grant you that there were many contributors. Among them were the Greeks Apollonius and Pappus who worked out the geometry of conic curves such as the ellipse; Ptolemy who forced Mars to do loop-the-loops to conform to the traditional earth-centered spheres model; Copernicus, who proposed a simpler, more sensible sun-centered model; Leonardo who wanted to fly up there and investigate; Galileo who dared to look and saw our Moon suffering with acne, Venus with Moon-like phases, Saturn with big ears, and Jupiter with its own little lunar system goin’ on; and the Dane Tycho Brahe who supplied my hero with the observational data.


Skipping past the Man of the Month momentarily, we have Napier, who brought logarithms to relieve the tedium of calculation for astronomers who, after all, had been up all night; Edmund Halley, of comet fame, who prodded Newton to publish his calculus and the explanation of the new Keplerian model; and many others up to and since Einstein, whose general relativity perfected the model.


Who did I skip? Merely the author, according to James Connor,* of the first book of modern science. The man who vindicated Copernicus and Galileo, who solved the enigmas in Brahe’s data. The man who was imaginative enough to invent a planetary model based on the nesting, a la Russian dolls, of geometric solids; persistent enough to grind out thousands of calculations to support another model; flexible enough chuck his first one out the window when he realized the truth; and bold enough to write the book Astronomia Nova and turn a thousand years of doctrine supporting Aristotle on its head. The author was Johannes Kepler. Oh, I should mention he would have cast your horoscope as well, being an icky astrologer, but hey, back in those days, that work paid the bills.


Kepler was unconventional in many ways. He was a devout scientist, a Lutheran who tried to placate both sides in the Counter-Reformation. He was a teacher hired and fired numerous times. His fortunes in serving kings and princes rode a similar wave as battles and religious neuroses grew and ebbed like an inland tide across Europe. Kepler even halted his progress in the sciences, both real and pseudo, to fight the persecution and prosecution of his mother.


Kepler believed in a God who designed a universe whose secrets were solvable given keen insights and hard work, but one whose secrets were a bit more complicated than in the Aristolean ideal. Brahe, who was in failing health, hired him as assistant and challenged him to solve the Mars problem. The data showed that its orbit was not a perfect circle and that the planet would speed up and then slow down. Kepler, whose confidence approached downright arrogance, made a bet that he would have the answer in eight days.


conic sections
Pietros Sacanis. Wikimedia, Public Domain

Kepler kept at the problem for six years. He made arduous trigonometric calculations which would have been eased if Newton’s calculus had been invented. Thanks to the preservation of classical works, in the Near East, Ireland and other places, appreciative Renaissance scholars were re-examining them – and among them were residing the innocent-looking, seemingly inapplicable conic curves. “If not a circle, why not an ellipse,” Kepler wondered. A six-year grind through the data showed this to be the case. Kepler was flexible enough to give up his previous model, and he devised the data-supported three laws of planetary motion that still hold true today. It was then that Kepler’s question became “Why ellipses?” And that unanswered question, he admitted, nearly drove him insane.


Curiosity, imagination, faith, persistence, and flexibility – those are the qualities that made Kepler a man of modern science, and our Man of the Month.


*Connor, James A. Kepler’s Witch. Harper, 2004