Tycho & Kepler: The Unlikely Partnership That Forever Changed Our Understanding of the Heavens

Tycho & Kepler: The Unlikely Partnership That Forever Changed Our Understanding of the Heavens , Kitty Ferguson Walker, New York, 2002. $28.00 (402 pp.). ISBN 0-8027-1390-4

Kitty Ferguson has made her reputation as a historian of science who writes for a broad general audience. Among her well received works are Stephen Hawking: Quest for a Theory of the Universe (F. Watts, 1991), Prisons of Light: Black Holes (Cambridge U. Press, 1996), and Measuring the Universe (Walker, 1999). In her most recent book, Tycho and Kepler, the author recounts the famous tale of two highly gifted natural philosophers, one the greatest naked-eye observer in history, the other the formulator of the first mathematical laws of the heavens.

A product of great wealth and privilege, Tycho Brahe ruled the island of Hven—a gift from the king of Denmark—like a medieval lord. There, by virtually enslaving the resident population, he built Uraniborg, the world’s most advanced observatory. Charting the night skies with massive instruments of his own design, he accumulated a trove of precious data, the accuracy of which set him apart from all astronomers, living and dead.

It was also on Hven that Tycho developed his idiosyncratic model of the universe. Opposed to the Copernican system for religious reasons, yet fully cognizant of the growing anomalies in the Ptolemaic model, he fashioned a grand compromise. In Tycho’s system, Earth was an immobile body around which the Sun revolved, and the five planets then known revolved around the Sun.

Johannes Kepler, by contrast, came from humble circumstances. The son of a ne’er-do-well mercenary who was often absent from home for years at a time, he had grown up with a major inferiority complex reinforced by his small stature and the poor eyesight that barred the way to a life of observation. His strength, too, lay in the opposite direction of Tycho’s—a great theoretical mind fired by a capacity for mathematics that can only be described as genius.

Only after 16 chapters of prologue do the principals finally meet at Benatky Castle outside Prague. Tycho, unable to control his mercurial temper, has severed all ties to the Danish king and court and cast his lot with Emperor Rudolph II, one of the great scientific patrons of the day. After corresponding with Kepler and reading his published work, Tycho decides to take a chance on the young astronomer, though he is very uncomfortable with Kepler’s Copernican leanings.

A symbiotic, albeit stormy, relationship ensues, which Ferguson recounts in colorful detail. Tycho’s data, especially that apparently showing an eccentric orbit of Mars, is exactly what Kepler requires to transform astronomical theory into scientific fact. An aging Tycho comes to realize that without Kepler to interpret and analyze his work, all could be lost. On his deathbed, the Danish nobleman begs the German commoner to renounce the heliocentric system: “Let me not seem to have lived in vain.” Kepler, of course, does nothing of the kind. Instead, he spends the following years plowing through Tycho’s precious data, eventually wringing out of it his famous three laws of planetary motion while failing, by the skin of his teeth, to solve the riddle of gravitation.

The story is one well known to historians of science and doubtless to many general readers as well. Still, it is a tale well worth the retelling. Ferguson is a fine writer and milks the double drama of clashing personalities and scientific discovery for all they are worth without crossing the line into fiction. The scientific concepts are clearly delineated, and the reader will deeply appreciate the many enlightening diagrams and photographs. Although Tycho and Kepler is not a work of original scholarship, it is a captivating story drawn from the greatest subject known to humankind—the very universe itself.