Tycho and Kepler

by Kitty Ferguson

  About the Book

  The extraordinary, unlikely tale of Tycho Brahe and Johannes Kepler and their enormous contribution to astronomy and understanding of the cosmos is one of the strangest stories in the history of science.

  Kepler was a poor, devoutly religious teacher with a genius for mathematics. Brahe was an arrogant, extravagant aristocrat who possessed the finest astronomical instruments and observations of the time, before the telescope. Both espoused theories that seem off-the-wall to modern minds, but their fateful meeting in Prague in 1600 was to change the future of science.

  Set in one of the most turbulent and colourful eras in European history, when medieval was giving way to modern, Tycho and Kepler is a double biography of these two remarkable men.

  CONTENTS

  Cover

  About the Book

  Title Page

  Dedication

  Maps

  Acknowledgments

  Prologue

  1. Legacies

  2. Aristocrat by Birth, Astronomer by Nature

  3. Behavior Unbecoming a Nobleman

  4. Having the Best of Several Universes

  5. The Isle of Hven

  6. Worlds Apart

  7. A Palace Observatory

  8. Adelberg, Maulbronn, Uraniborg

  9. Contriving Immortality

  10. The Undermining of Human Endeavor

  11. Years of Discontent

  12. Geometry’s Universe

  13. Divine Right and Earthly Machination

  14. Converging Paths

  15. Contact

  16. Prague Opens Her Arms

  17. A Dysfunctional Collaboration

  18. “Let Me Not Seem to Have Lived in Vain”

  19. The Best of Times

  20. Astronomia Nova

  21. The Wheel of Fortune Creaks Around

  22. An Unlikely Harmony

  23. Measuring the Shadows

  Picture Section

  Appendix 1: Angular Distance

  Appendix 2: Vocabulary of Astronomy

  Appendix 3: Kepler’s Use of Tycho’s Observations of Mars

  Notes

  Bibliography

  Picture Acknowledgements

  Index

  About the Author

  Also by Kitty Ferguson

  Copyright

  TYCHO & KEPLER

  The Unlikely Partnership That Forever Changed Our Understanding of the Heavens

  KITTY FERGUSON

  To my sister, Virginia

  ACKNOWLEDGMENTS

  The author wishes to express her heartfelt thanks to Owen Gingerich, whose scientific, historical, and bibliographical expertise is exceeded only by his patience, for reading the manuscript and offering corrections and advice; to Sir Brian Pippard, who offered extremely welcome insights on the work of Kepler; to Henrik Wachtmeister, whose family has owned Knutstorps Borg since 1771, and who, after we met him unexpectedly in the churchyard at Kågeröd, graciously welcomed me and my husband and daughter to his home and offered me the use of an extraordinary seventeenth-century drawing of Knutstorps; to Yvonne Björkquist of the Tycho Brahe Museum on Hven, who showed us the sites of Uraniborg and Stjerneborg; to several helpful women at Benatky, whose names I never learned, who did their best to overcome the language barrier and give us an understanding of the layout and history of the castle; to my husband, Yale, and my daughter, Caitlin, who shared these research adventures, navigated the back roads of Sweden and the Czech Republic, took photographs, and read the manuscript; to Anselm Skuhra, who knew the way through the labyrinth of European interlibrary loans and risked his reputation with the University of Salzburg library when I failed to return books on time; to Justin Stagl, whose expertise in European social history rapidly cleared up many mysteries about calendar changes, the politics of the era, and the various names of the river that runs through Prague; to Karoline Krenn, who translated Kepler’s writing for me and whose expertise in the period made her translation all the more discerning and accurate; to Gabriele Erhart, whose knowledge of European libraries, galleries, and museums and computer expertise were invaluable for locating illustrations; to Alena and Petr Hadrava, who helped me reach illustration sources in Prague; to James Voelkel, who helped me locate two difficult-to-find pictures; to my literary agents in Europe and America, who read the manuscript at various stages and offered continual encouragement; and to my editors at Walker & Company in New York and Headline Publishers in London, for their splendid work on this book.

  PROLOGUE

  ON JANUARY 11, 1600, the carriage of Johann Friedrich Hoffmann, baron of Grünbüchel and Strechau, rumbled out of Graz and took the road north. The baron was a man of great wealth and culture, a member of an elite circle of advisers to Emperor Rudolph II of the Holy Roman Empire. Having fulfilled, for the time being, his occasional duties as a member of the Styrian Diet in the Austrian provincial capital, he was returning to court in Prague, the glittering hub of European political and intellectual life.

  Among Hoffmann’s acquaintances in Graz was a man considerably beneath his own station in society, an earnest young schoolmaster and mathematician named Johannes Kepler. Hoffmann was impressed by Kepler’s intense interest in astronomy, an interest he shared, and was aware that Kepler’s talents far surpassed those of an obscure provincial teacher. He also knew that Kepler’s present situation as a Protestant in Graz was precarious, for the Counter-Reformation was raging there. Only Kepler’s position as district mathematician and the expertise he brought to composing annual astrological calendars that predicted everything from crops to wars had prevented his being expelled from the city in 1598 along with other Protestant teachers and ministers. Hoffmann, for all his lofty status, was a thoughtful, kindly man. It had occurred to him that he might do his youthful friend a service by offering him a ride to Prague in his carriage at no cost to Kepler, who could ill afford such a journey, and an introduction to a far more experienced and distinguished astronomer who had recently arrived there—whose nose was made of gold and silver.

  The magnificent Tycho Brahe, the man with the extraordinary nose, was reputedly a difficult person. He had fallen foul of the Danish king and nobility and fled south as a princely refugee with his common-law wife, their six children, wagonloads of fabulous astronomical and alchemy equipment, and three thousand books. Hoffmann’s own library was his passion. He was the sort of man to be drawn to an intellect such as Tycho’s and also to admire the brilliant networking that had brought Tycho to Emperor Rudolph. In Prague, Tycho Brahe had flowed through the court like fine honey. Rudolph, an eccentric collector of all manner of curiosities, had welcomed him and promised to support him and his learned pursuits in munificent style.

  Hoffmann’s invitation to ride in his carriage to Prague was a godsend to Johannes Kepler. There was no man in the world whom he so longed to meet as Tycho Brahe. Kepler had already made inept but not entirely fruitless overtures to him. Tycho had had kind, if condescending, words to say about Kepler’s first book and had hinted that he would welcome Kepler to join his coterie of assistants. Alas, Tycho Brahe had been too far away in northern Europe and the journey prohibitively expensive. Suddenly, by the grace of God (Kepler had no doubt that God had a direct hand in such matters), Tycho had moved closer, and Kepler had a free ride to Prague. Never mind that it was a one-way ticket, that he had to leave his wife and stepdaughter behind, that Tycho might not be as eager to meet him as he was to meet Tycho, that there was no guarantee a paying job would result. When the baron’s carriage drove out of Graz on January 11 and the driver set the horses to the road north, young Kepler was on board.

  The journey took ten days, and Tycho Brahe was not in the city when they arrived. He was at Benatky nad Jizerou, a clifft
op castle several miles to the northeast. Kepler stayed for a few days as a guest in Hoffmann’s palace, considering how best to approach Tycho. Then on January 26, a letter arrived from the great man himself, who had heard that Kepler was in Prague. “You will come1 not so much as guest,” Kepler read, “but as very welcome friend and highly desirable participant and companion in our observations of the heavens.” Kepler was apparently not to be just one additional beginner assistant.

  Nine days later, on February 4, carrying a glowing letter of introduction from Baron Hoffmann, Kepler rode out of Prague, this time in Tycho Brahe’s own carriage with Tycho’s son, also named Tycho, and an elegant young man named Franz Tengnagel. They crossed the Labe River at Brandeis, where the emperor had a luxurious hunting lodge, and continued through wooded countryside. The trees, except for the numerous pines, were bare. It wasn’t until the next day, February 5, that they reached the first significant change in the landscape, the bluff above the Jizerou River. Poised on top, near the cliff edge, was a square three-story structure of generous but pleasing proportions. It was not the formidable, gloomy fortress some castles were. Perhaps Kepler saw—for it had either been completed then or was in the process of creation—a wonderful fresco covering one entire exterior wall, showing hunting scenes with Emperor Rudolph prominently featured.

  Kepler counted among his acquaintances several men such as Hoffmann who were of much greater social stature and wealth than himself. Nevertheless, the lord of Benatky whom he met that day came from a world almost completely outside his previous realm of experience and, in spite of their shared scholarly interests, largely beyond his understanding. Kepler was a well-educated but poorly paid schoolmaster who had spent his childhood in an impoverished, dysfunctional family in small towns on the edge of the Black Forest. By his own description he resembled a little house dog, overeager to please—only occasionally attempting to assert himself by growling or barking and, when he did, succeeding only in causing people to avoid him. Tycho Brahe was renowned throughout Europe as a prince among astronomers and an astronomer among princes; he was supremely well aware of his own superior intellect and status; and he regarded lesser men as just that: lesser men, some of whom he liked and treated well, others not. At the time he met Kepler, he was feeling his age, fifty-three years. Bruised by recent defeats at the hands of enemies in Denmark, he was discouraged about the present state of his work. Nevertheless, he was on his feet again in a different court, lord of an imperial castle, with a promised income from the Holy Roman Emperor that was greater than that drawn by any other man at court. His current public image in Prague was as an elegant and extrovert luminary. Some who had encountered him in different contexts knew he could also be an overbearing, combative, paranoid, and even somewhat malevolent figure.

  Though Kepler may have been becoming aware of his own genius, he was still a modest, pious, unassuming, ill-at-ease twenty-eight-year-old in the thrall of a glamorous, formidable, somewhat jaded world figure. Yet in Kepler the mighty Tycho met his match. If Tycho was the dragon of fairy tales, coiled on a fabulous golden hoard—the astronomical observations that he had spent years and a fortune making and now would let almost no one see—then Kepler was the unpromising folklore antihero who was nevertheless endowed with the power to wrest that treasure from him and, from it, forge a new astronomy.

  Modern scientists and historians, with hindsight, know this is precisely who Johannes Kepler was. The kindly Hoffmann didn’t know; nor did Tycho’s son, or Tengnagel. No one at Benatky Castle suspected . . . with the possible exception of Tycho Brahe himself.

  Aware only of what Tycho and Kepler had accomplished before that February day when they met, one would not be likely to identify either of them as a prime candidate for immortality. Both men were engaged in developing theories that to modern eyes seem hopelessly misguided. Yet Johannes Kepler and Tycho Brahe would turn out to be two of a mere handful of men who would precipitate humanity into the modern era of scientific inquiry and discovery. When Kepler’s exceptional gifts of imagination and inventiveness, his insistence on mathematical rigor and reasonable physical explanations, and his belief that God had created a universe in which harmony and logic prevail came to grips with Tycho’s superb, unyielding observational data, the result would be the revelation of profound laws that govern how the heavenly bodies move. Kepler’s struggle to find those laws would itself become a prototype for what science would be from that time forward. Sir Isaac Newton was referring to Copernicus, Tycho Brahe, Kepler, and Galileo when he said he had stood “on the shoulders of giants.”

  The colorful, dangerous world in which Tycho and Kepler lived and worked—the courts, universities, cities, palaces, and hovels of Renaissance Europe—afforded them little peace. Against this background, shaped by it and often at its mercy, they nevertheless stood as towering figures not really conformed to any age or time. Nor was their genius the only thing that set them apart. On a more superficial level, they were truly eccentric personalities. Either man, if encountered in a novel, would seem a fantastic or even absurd invention. The same can be said of many of their acquaintances: the unabashedly villainous Nicolaus Bär, the reclusive emperor Rudolph with his largely imaginary royal treasury, the rascal Rosenkrantz who sparked Shakespeare’s interest, Kepler’s mother Katharina, who was tried for witchcraft. . . .

  In this setting and among these people, all manner of events conspired to foil Tycho’s and Kepler’s loftiest and best-considered plans, destroy their happiness, and distract them from their science. However, this same chain of events brought them together and thus secured for them an immortality that they probably would not have achieved otherwise. No wonder Kepler concluded that the benevolent will of God led men along desperately unwanted paths that only later could be recognized as the right ones.

  If invisible cords drew Tycho Brahe and Johannes Kepler over the passage of many years to their crucial encounter, and to the brief, strife-torn, amazingly fruitful relationship that followed it, those strands seem to have been moving almost from the moments of their births.

  1

  LEGACIES

  1546–1561

  THE ORIGIN OF the Danish castle Knutstorps Borg—in what was once part of Denmark but is now southwest Sweden—pre-dates written and even oral records. One ancient section of wall in the cellar comes from an eleventh-century structure, but no one knows who lived there then or what the building looked like, secluded among gentle folds of meadow and woodland. There are records from the fourteenth century of an inhabited stone keep. It was probably surrounded by the small lake that appears in sixteenth-century drawings. By that time the keep had become a substantial castle home, the ancestral seat of the noble Brahe family. The lake served as a defensive moat with a causeway and drawbridge.

  Here, on December 14, 1546, more than half a century before Johannes Kepler’s winter journey to Prague and Benatky, Beate Bille, wife of the Danish knight Otte Brahe, gave birth to twin sons. Only one of them lived, and he was christened Tyge (pronounced “Teeguh”), probably in the small stone parish church of the manor at Kågeröd. Tyge, who would later Latinize his name to Tycho, was Otte and Beate’s first son and second living child. His parents did not tell him that he had been a twin.

  He was also kept ill-informed about an unusual episode in his early childhood. When Tyge was two years old, his young uncle and aunt, Jørgen Brahe and Inger Oxe, abducted him from his parents’ castle and carried him to their own stronghold at Tostrup. As far as records show, and as Tycho Brahe understood this bizarre incident when he was older, there was no outraged protest from his mother or father, no family schism, no scandal, and no attempt to recover him. Otte and Beate by then had a second son, Steen, and were expecting another baby. Tycho would later write simply that his uncle Jørgen “without the knowledge1 of my parents took me away with him while I was in my earliest youth.” It seems that was all Tycho knew.

  Short of being a member of the royal family, it was impossible to be higher
born than young Tyge.fn1 His ancestors and his relatives had for generations been powerful leaders who served the Danish kings with consummate skill and loyalty, who knew how to maintain a position of influence amid shifting factions at court and how to regain that position if it happened through some stroke of misfortune to be temporarily lost. On the Brahe side the men were warrior knights, at home in the heavy-drinking military circles of the Danish court and ably commanding and administering royal fiefs. Tyge’s great-uncle Axel had been one of the first Danish aristocrats to reject Catholicism, so effectively supporting the Lutheran king Christian III during the Reformation in Denmark in the 1530s that he was chosen to carry the scepter at the coronation in 1537. Tyge’s father Otte and his uncle and foster-father Jørgen honed their courtly and military skills during that same period of political and religious upheaval. In 1540, six years before Tyge’s birth, the king granted them the joint fiefdom of Storekøbing, a step toward increasingly strategic fiefdoms. Otte would eventually become governor of Helsingborg Castle, the fortress that guarded the Øresund—the crucial strait that led from the North Sea to the Baltic (see map, Tycho’s Denmark). He would also hold a seat in the Rigsraad, a body of twenty nobles whose responsibility it was to seat kings, appoint regents, declare war, make treaties, and work with the king on a daily basis in affairs of state.

  Tyge’s forebears on his mother Beate Bille’s side of the family had combined that same kind of secular service to the king with high ecclesiastical positions, and these connections had allowed considerable wealth to be channeled to family members who did not enter the church. When the Reformation came in the 1530s, no fewer than six Billes were in the Rigsraad, and most commanded important castles in Denmark and Norway. Less fortunately, seven of the eight Catholic bishops of Denmark were blood relations, linking the family embarrassingly with what turned out to be the losing side. However, by the time of Tyge’s birth the Billes were rapidly repairing their fortunes. The marriage of Beate Bille to Otte Brahe was part of that recovery.