KEPLER'S WITCH

An Astronomer's Discovery of Cosmic Order Amid Religious War, Political Intrigue, and the

Heresy Trial of His Mother

By James A. Connor. HarperSanFrancisco. 402 pp. $24.95

HEAVENLY INTRIGUE

Johannes Kepler, Tycho Brahe, and the Murder Behind One of History's Greatest Scientific Discoveries

By Joshua Gilder and Anne-Lee Gilder

Doubleday. 304 pp. $24.95 One of the delights of reviewing is to have your expectations overturned. I was doubly lucky with these two books. When I first looked at them, I anticipated that Kepler's Witch would be an intriguing account of one of the more obscure events in the life of the great astronomer Johannes Kepler but that Heavenly Intrigue, which suggests that Kepler murdered his patron Tycho Brahe, would be the work of cranks with no real understanding of history. I was wrong on both counts.

Kepler lived from 1571 to 1630, making him a contemporary of William Shakespeare and Galileo Galilei. The Pilgrims founded the Plymouth colony when Kepler was 49. He was one of the giants on whose work the Scientific Revolution was based, and in particular he worked out the laws of planetary motion, later used by Isaac Newton in developing his theory of gravity. Indeed, it is often wrongly assumed that Newton's famous remark about "standing on the shoulders of giants" refers to people like Kepler and Brahe. In fact, Newton made that remark in the context of his work on light, long before the theory of gravity was developed; but as a metaphor, it is still a good description of the relationship between Kepler and Newton.

Kepler had a tough life, starting out in poverty in the German town of Weil der Statt, with an abusive father. He suffered a childhood attack of smallpox that left him with weak eyesight and later forced him to depend on the observations of other astronomers (notably Brahe) for the data he needed. And he did, indeed, have to witness his elderly mother go on trial for witchcraft.

Kepler's story has all the makings of a gripping biography. But James Connor's book is not that biography. It contains all the facts, but it is a dull read, overlong, and the author wears his learning too self-consciously. In spite of the title, the story of the witchcraft trial is not central to the book, and the treatment given here only serves to highlight how interesting a shorter, more focused account of this aspect of Kepler's life could be.

The most surprising feature of the book, to anyone who has studied Kepler's life, is Connor's claim that his subject went through a serious "embrace of astrology," something that "more than anything else . . . puts Kepler at a distance from our age." Actually, the impoverished Kepler cast horoscopes only to make money, and in his private correspondence referred to his clients as "fatheads" and described astrology as "silly and empty." This makes him much more in tune with modern thinking than most of his contemporaries.

But if Kepler's Witch is disappointing, Heavenly Intrigue is a delight. Joshua and Anne-Lee Gilder have produced a much more crisply written chronicle of the colorful world of Kepler and his famous mentor, Brahe. The latter was an aristocratic Dane, who in his youth had fought a duel that resulted in a chunk being cut out of his nose, later protected with a silver covering; he presents a dramatic contrast with the low-born Kepler, always struggling to make ends meet.

The story culminates in their eventual meeting. This took place in Prague, where the aging Brahe (he lived from 1546 to 1601) had a treasure trove of planetary observations, going back decades, but lacked the mathematical skills to use these data to find the exact orbits of the planets. The younger Kepler had the mathematical skills, but not the data.

It should have been a marriage made in heaven, but for reasons that the Gilders make clear, Brahe was reluctant to part with his data, and Kepler was eager to get on with the job. It was only after Brahe died that Kepler, the obvious scientific heir, was able to get hold of the material he needed. Contemporary accounts tell us that Brahe was at a banquet in honor of a distinguished guest, and out of politeness did not leave the table to relieve himself during the extended meal in spite of drinking large quantities of wine. When he eventually tried to pass urine, he failed; and a few days later died in considerable pain, naming Kepler as his scientific heir on his deathbed.

But Brahe's sudden death surely concealed some broader underlying cause of his fatal discomfort -- perhaps an infection. One possibility that would fit the accounts is mercury poisoning, and this is the case that the Gilders make. But unlike other authorities, they suggest that the mercury was ingested not as an accidental consequence of Brahe's alchemy experiments, but through the hand of an enemy -- that is to say, Kepler.

Was Kepler eager enough to get his hands on the data to have poisoned Brahe? I don't think so, but this account of what might have happened is an enthralling read, as a murder mystery being investigated four centuries after the death. Even regarded as science fiction, it is informative and entertaining -- which would be appropriate, since Kepler wrote what many regard as the first science fiction story, an account of a mythical flight to the moon, designed to present some of his astronomical ideas in an accessible form.

Kepler himself would surely have loved the Gilders' book, even as a work of fiction. He would have appreciated the way the authors use the murder mystery as a peg for the science and biography -- though he doubtless would have taken strenuous note of the lack of compelling evidence to support the tale. And he might, from a distance, have appreciated the ironic echo of his mother's misfortunes in this version of the story. *

John Gribbin is a visiting fellow in astronomy at the University of Sussex, and author of "The Scientists."