Tycho and Kepler (14 page)

Johannes gave an equally unsympathetic picture of his grandmother.
She was a restless woman, thin, fiery-tempered, resentful, clever, “blazing with hatred,” “violent, and a bearer of grudges,” and a liar. She was also devoutly religious.

Johannes’s father, Heinrich, was their fourth son, and he, by his own son’s report, was a vicious, immoral, brutish, uneducated man. “He destroyed everything. He was a wrongdoer, abrupt, and quarrelsome,” and he “beat his
wife often.” Theirs was “a marriage fraught with strife.” Through a combination of bad behavior and bad luck, Heinrich had brought the Kepler family to an unprecedented low. Before Johannes was three, Heinrich set off adventuring and fighting as a mercenary. He returned only occasionally to his wife and children, and his short stays were not happy.

The task of raising Johannes and his brothers
and sisters—there were seven children, four of whom survived to adulthood—fell mainly to their mother, Katharina. She was the daughter of another prominent civic leader, the bürgermeister of nearby Eltingen, Melchior Guldenmann, who was also an innkeeper. Kepler described his mother as small, thin, dark-complexioned, garrulous, quarrelsome, not a pleasant woman. Her acquaintances regarded her
as an evil-tongued shrew.

Young Johannes, the eldest of the children, resembled Katharina in appearance. They were also alike in having restive, inquiring minds, but Katharina had no education, and her interests were herbs and homemade mixtures for healing. What in her son would develop into a rich intellectual curiosity was, in her, often only nosiness. When Heinrich was at home, she responded
with pouting and stubbornness to his harsh, rude treatment. “She could not,” wrote Kepler with pity, “overcome the inhumanity of her husband.”

Kepler also described aunts and uncles and some cousins who lived in the house in Weil der Stadt. Among them were Uncle Sedaldus, who was “an astrologer, a Jesuit, acquired a wife, caught the French sickness, was vicious,” and Aunt Kunigund, who was
poisoned and died.

In the spring of 1575 Katharina Kepler left three-year-old Johannes and his infant brother in the care of these relatives and went off to follow her soldier husband Heinrich. In her absence Johannes nearly died of smallpox, probably the illness that impaired his vision. The prodigal parents returned after a year.

With both nature and nurture decidedly against the two
Kepler brothers, their future looked bleak. Johannes was puny and weak-sighted. Heinrich, two years younger, was an epileptic. Johannes recalled that Heinrich was beaten roughly, and animals frequently bit him. He nearly drowned, nearly froze to death, nearly died of illness, and ran away from his apprenticeship to a baker when his father threatened to “sell him.” After that he appeared only occasionally
at home, much as his father did, often returning bruised and broken, robbed of everything he had, making his way back by begging. All his life—he died at the age of forty-two—his mother considered him the bane of her existence.

The younger Kepler children turned out better. Margarethe, a gentle, sympathetic girl, later married a clergyman, and she remained close to Johannes and loyal to her
mother even through the worst of times. The youngest surviving sibling, Christoph, grew up to be an
honorable
, correct man, though not so unfailingly loyal as his sister. He became a respected craftsman, a pewterer.

The little city of Weil der Stadt, surrounded on all sides by the duchy of Württemberg, nevertheless enjoyed the status of an imperial free city within the Holy Roman Empire and
sent its own representative to the Imperial Diet. Though its name implied that the Holy Roman Empire was in some way the legatee of the Roman Empire, the standard and fairly accurate quip is that it was not holy, not Roman, and not an empire. Ruled in theory by the Holy Roman Emperor in Prague and the Imperial Diet, it was made up of many units—duchies like Württemberg, cities like Weil der Stadt,
bishoprics, and other principalities—that today have become Germany, Austria, and the Czech Republic, as well as parts of Poland, France, and Holland and sundry other bits and pieces of Europe.

Under the 1555 Peace of Augsburg each local leader decided whether Catholicism or Lutheranism would be practiced in his domain. An exception was made for free imperial cities like Weil der Stadt: If
both religions had previously been practiced there, both were allowed to continue. The duchy of Württemberg, which surrounded Weil, was by decree of its powerful duke officially and vehemently Lutheran. Weil itself was mostly Catholic, but there were Lutherans there as well. The Keplers were part of this Lutheran minority—a not entirely comfortable situation, though grandfather Sebald seemed not
to have found it an impediment to political advancement.

In 1576 Johannes’s father renounced the right of citizenship in Weil and moved his young family to Leonberg, not far away but part of Lutheran Württemberg. It was from the hill above that town that Katharina and Johannes viewed the comet.

T
YCHO
B
RAHE
and other scholars, though
not immune to the disquiet about the comet felt by less educated people like the Keplers,
undertook
to study it zealously from a scientific point of view. Tycho’s first step was to write a careful description
⁵
and make a drawing. The comet’s head was seven to eight arcminutes in diameter and bluish white, the color of Saturn. Its tail was reddish, like a flame seen through smoke. To pinpoint its
position, he measured its angular distance from two prominent stars. Tycho wanted to find out how far away from Earth the comet was, and that meant, as it had for the nova, finding out whether it displayed any parallax shift.

Looking for the comet’s parallax presented new challenges. It was positioned too near the Sun to be visible except for an hour or so just after sunset, and that was too
short an interval for Tycho’s position on Earth to change sufficiently to provide any perspective on it. Furthermore, it was known that comets were in motion. With the nova, Tycho had been able to assume that
any
movement it displayed against the background was a manifestation of parallax. He could assume no such thing for a comet. Its change of position against the background would be partly,
maybe totally, attributable to its own motion. Without knowledge of what that motion was, any attempt to measure parallax would be futile.

Partly due to cloudy weather and the wait for longer evening visibility as the autumn days grew shorter, it took Tycho ten days after he first saw the comet to determine that it moved an average of about three degrees of arc per twenty-four hours. Because
every twenty-four hours brought Tycho back to the same viewing position, that motion could not be attributable to parallax: It had to be the comet’s own motion. Three degrees of arc per twenty-four hours is about seven and a half minutes of arc per hour. Tycho next made observations three hours and five minutes apart, during which interval the comet’s own motion—the seven and a half minutes of
arc per hour—should have moved it, he calculated, about twenty-three minutes of arc. If it appeared to move
more or less
than that, the difference would be attributable to a parallax shift. Tycho found that the
comet
appeared to move only twelve minutes of arc. Parallax shift, he concluded, had to account for the other eleven minutes of arc

That result was disappointing. It was a borderline
case whether this amount of parallax indicated that the comet was above or below the Moon. Further study soon yielded something more decisive. Tycho reconsidered the comet’s daily intrinsic motion and found it closer to two degrees than three. He did the calculations again, and this time he discovered almost
no
motion left over to be accounted for by parallax. Additional observations near the
end of December bolstered the case for the comet having virtually no parallax at all. Tycho saw the fading comet for the last time on the twenty-sixth of January, when the Moon, which had drowned out the comet’s light for two weeks, had waned enough to allow him one last glimpse. He had already begun to write his conclusions.

Tycho felt he had settled the question of whether comets are closer
than the Moon or farther away. Aristotle had been wrong about the “unchanging” heavens. This comet was a change, and it was indisputably beyond the Moon, though Tycho could not specify precisely how far beyond.

Tycho reached a second conclusion. The comet moved in the same direction the planets move, and this movement had for the first week carried it out very rapidly in front of the Sun,
but after that it had moved more slowly and become dimmer, suggesting it was moving farther away from Earth. Then the Sun had begun to catch up again. Tycho concluded that the comet was orbiting the Sun.

He began to plan a book. He knew from previous experience that it was difficult to change the views of his colleagues and the public that followed them blindly. His new book needed to be more
rigorous, more detailed, longer, than its competitors. While the comet was still visible, Tycho started a notebook of star observations so that he could use his own coordinates for reference stars to locate the comet rather than rely on the old catalogs.

The first order of business, however, was to file a private report to the king. It was only a little embarrassing that Frederick had seen
the comet two days earlier than Tycho. Someone at Sorø Abbey, where the court was lodged at the time, had pointed it out. Tycho had also been preempted in his royal reporting by one Jørgen Dybvad, an open-minded man when it came to Copernican astronomy but preoccupied in the present case with what the comet portended. His pamphlet predicted bad weather, crop failure, religious troubles, pestilence,
war, even that “the day of the Lord . . . is at hand.” Dybvad was an ambitious and powerful figure at court and in the university and a potential competitor. Tycho saw an opportunity to best him.

His report to Frederick began with a description of the comet, including technical details that he promised to expand on in a later, more formal publication. This material could not have been of enormous
interest to Frederick, but Tycho saw it as a way of reinforcing his image as an expert and giving greater credence to his interpretations as an astrologer. The next part of the report obviously referred to poor Dybvad: “Pseudoprophets
⁶
who have thought [that comets might presage the apocalypse] and have mounted too high in their arrogance and not walked in divine wisdom will be punished.” Tycho
was not, however, ready to say there was nothing to worry about. Historically, he reminded the king, comets had always meant “great scarcity . . . many fiery illnesses and pestilence and also poisonings of the air by which many people lose their lives quickly . . . great disunity among reigning potentates, violent warfare and bloodshed and sometimes the demise of certain mighty chieftains and secular
rulers.” Because of its position in the sky and other characteristics, this comet was worse than usual and augured “an exceptionally great mortality among mankind.”

With his reader now brought to the point of despair, Tycho advanced the more soothing and optimistic theme of the arguments he had made in his first university lecture—that heavenly events do
not
determine the future. Resorting
to anguished prayer was not the proper course, he advised, for rational exercise of free will and appropriate action could change the effects of the comet. The king might even prepare in advance to reap the benefits if the prediction about the “demise of certain mighty chieftains and secular rulers” should turn out to apply to Ivan the Terrible of Russia. And Frederick would be wise to get ready
for “Spanish treachery” if the comet had special “significance over the Spanish lands and their reigning lords.” Tycho continued in this vein, knowing that these interpretations in terms of political policy would appeal to Frederick. When it came to demonstrating the value of astronomy and astrology to the king—and implying that it was an extraordinary advantage to have Tycho himself at the king’s
right hand rather than a defeatist like Dybvad—Tycho was playing it to the hilt.

The report also revealed a trend in Tycho’s thinking—or perhaps it was merely rhetoric—that the king may not completely have shared. Tycho painted himself as a man who not only abhorred the politics of court life but also longed for peace and justice on a wider than personal scale. The comet, he wrote, might mean
“well-deserved punishment for inhumane tyranny,” and for “those who were associated with [violence and warfare], those who are always on the prowl [causing] great injury to others.”

If the peasants on Hven had been able to read their master’s hyperbole about “well-deserved punishment for inhumane tyranny,” they might well have responded with rude noises, for during the same visit Tycho asked
Frederick for assistance in dealing with the peasants who were fleeing Hven. These deserters, Tycho pointed out correctly but also self-righteously, were violating the law of villeinage and thus placing a greater burden on those who remained. The king’s reply made it clear that the law that applied elsewhere also applied on Hven: Tenants could leave an estate only with the permission of their lord.