Tycho and Kepler (7 page)

Alchemy required glassware, and a master of the Venetian art of glassmaking, Antonio de Castello Veneziano, with a retinue of assistants,
arrived in Denmark, possibly on the run, for the Venetian Republic was extremely possessive of its glass industry. Steen invited them to make their home at Herrevad, adding Venetian dialect to the mix of Danish and Latin already spoken there. Soon the glassmakers were producing not only alchemy vessels for Steen and Tycho but also drinking glasses and windowpanes for King Frederick and Queen
Sophie.

One of Tycho’s first undertakings at Herrevad was to construct a new astronomical instrument, a “half-sextant” with straight walnut legs and a curved brass arc. A little later he added a larger, interchangeable sixty-degree arc. It was this sixty-degree arc that gave a “sextant” its name—probably coined by Tycho himself (
see figure 3.1
). Sixty degrees is one-sixth of a circle; a half-sextant
has a thirty-degree arc. Sextants and half-sextants resemble slices of pie. By sighting along the two legs or sides (where the pie is “cut”)—pointing one leg toward one star and the second leg toward another, for example—it was possible to measure the angular distance between two heavenly bodies. One could similarly measure a body’s altitude above the horizon.

Tycho was getting more from this
effort than a better instrument. He was developing expertise and learning lessons that would serve him later. One conclusion Tycho reached was that in order to design and manufacture instruments capable of the precision he wanted, he would need highly skilled, specialist instrument builders working at his own facility, where he could supervise them. For the moment, he had to content himself with
getting the best results he could with nonspecialist artisans under his supervision, while ordering more intricate or decorative parts, and sometimes whole instruments, from Copenhagen. What began at Herrevad was never completely realized there, but the possibilities Tycho saw unfolding at the beautiful old
abbey
gave him a much clearer vision of what he hoped to accomplish and how to go about
it.

In that same watershed year, 1572, when Tycho ended his European wanderings and began to pursue his interests closer to home, he met—perhaps not for the first time—a young woman named Kirsten Jørgensdatter.
⁴
Like other key events in Tycho’s personal life, the beginning of his lifelong relationship with her is frustratingly undocumented. She was not a woman of noble lineage. (If she had
been, more would be known about her.) Pierre Gassendi, Tycho’s earliest biographer, reported a description that he got firsthand from one of Tycho’s last students: Kirsten was “a woman of the people
⁵
from Knutstorp’s village.” To this day, tradition in the Knutstorp area has it that she was a clergyman’s daughter and that her father was pastor of the Knutstorp parish church at Kågeröd, about two
miles from Knutstorps Borg.

The name Jørgensdatter indicates that Kirsten’s father’s first name was Jørgen. From 1546 to 1569 the pastor at Kågeröd was Jørgen Hansen. Most likely it was he who christened the infant Tycho and buried his twin brother. If Kirsten was his daughter, she must have spent her childhood in the half-timbered parsonage beside the little stone Kågeröd church while Tycho
was growing up in the castles of his uncle and father.

The family coats of arms of the Brahes and the Billes are carved on the arch of the Kågeröd church above the family pew. The pulpit in the church is situated not at the front but about halfway back, and the enclosed box pews have seats front and back so that if they are not too crowded, the occupants can move to face the pastor during
his sermon. If Tycho sat in the family pew during his visits to Knutstorps Borg, perhaps his eyes fell on Kirsten as the congregation shifted their seats. The young daughter of the pastor would have been modestly clad, neither like a peasant girl nor like a child of the aristocracy. As she grew to be a young woman, a white lace collar and cuffs probably would have been her only less-than-somber adornments.

Much later in the lives of Tycho and Kirsten, after two other pastors
had
come and gone, a Hans Jørgensen—again indicating that his father’s first name was Jørgen—was called to the Kågeröd church by the joint lords of Knutstorp, the brothers Tycho and Steen Brahe. Records show that this Hans Jørgensen visited Tycho at his island castle observatory that same year, 1591. Scholars have speculated
whether he went there only to be interviewed for the position or also to visit his sister, who by that time had been living for twenty years as Tycho’s wife.

Adding strength to the local tradition that Kirsten was the pastor’s daughter, not a peasant girl, is the fact that though casual liaisons between noblemen and peasant girls were not unusual, lifetime alliances were. Tycho’s relationship
with Kirsten Jørgensdatter was no mere youthful dalliance. It is much more likely that he would have chosen as his companion for life the daughter of an educated clergyman, with a family background and upbringing not quite so drastically different from Tycho’s own as a peasant woman’s would have been.

If Kirsten was Jørgen Hansen’s daughter, her position in society was indeed considerably
above that of a peasant, but there was still a daunting chasm between her station in life and Tycho’s. The nearest he had ever come to experiencing her world was when he lived with a clergyman during his school days, and that clergyman had probably been a bishop, certainly not a humble pastor. Kirsten would have grown up in obscurity in a thatched-roof cottage, working with her hands in the kitchen,
house, and garden, and probably never traveling more than a few miles from the village of Kågeröd. So far apart were their worlds that Inger Oxe and Beate Bille would have had difficulty imagining what Kirsten’s daily life was like, as Kirsten would have had difficulty imagining theirs.

However well Tycho and Kirsten would manage to bridge the gulf between their different upbringings, that
gulf, as it was formally imposed by Danish society, law, and tradition, could not be bridged. Tycho the nobleman and Kirsten the commoner could not legally become man and wife.

There was an alternative that was considered neither scandalous
nor
sinful. The earliest Danish law codes of ancient Jutland had recognized the legality of
slegfred
marriages; that is, common-law or morganatic marriages.
Under the ancient laws, which were still in force, a woman who was a commoner, who lived openly as a wife in a nobleman’s house for three winters, dining, drinking, and sleeping with him and carrying the keys to his house, was his wife. Originally, among the polygamous Vikings,
slegfred
had meant a wife of secondary status, but in Tycho’s day it had lost that connotation. When Tycho and Kirsten
began their relationship, the courts had just recently reaffirmed that the offspring of such a marriage were not bastards but
slegfred
children. However, they and their mother remained commoners, no matter how nobly born the father was, and the children could not inherit their father’s estates. None of the expectations and rights of a nobleman’s sons and daughters applied to them.

Tycho was
well aware that his choice of Kirsten strongly reinforced his image as a young man who was willing to flout convention, and that it would likely have drastic consequences for his future and for his descendants. The reputation and influence of his powerful extended family was also at stake. Family honor and alliances through marriage were of enormous importance to Tycho’s relatives. Their reactions
to his choice were, predictably, not enthusiastic. The only advantage for them was that the family inheritance would not have to be so widely shared. A few were actually sympathetic.

Surprisingly, Tycho’s morganatic alliance with Kirsten did not dim his hopes at court. King Frederick had reason to be understanding. He, like Tycho, had fallen in love with a woman beneath his station, Anne Hardenberg,
a noblewoman but not of royal blood. Frederick’s father, King Christian III, had forbidden their marriage. After the old king’s death, Anne had continued to live within the royal family as a part of the queen mother’s court, and King Frederick had refused to have anything to do with negotiations for a different bride.

However, when Frederick finally announced that he would enter into a morganatic
marriage with Anne, even though their children
could
never succeed to the throne, the opposition among the nobility at home and abroad was so vigorous that he in the end agreed to give up Anne and marry his fourteen-year-old cousin, Princess Sophie of Mecklenburg. Their marriage took place in July 1572, during the time when Tycho was falling in love and sealing his relationship with Kirsten Jørgensdatter.
Frederick invited all the Danish nobility, commanding them to dress in new court attire and ride their best horses, and each to accompany himself with two squires and a page. Tycho—not being a warrior knight—had no squires and pages of his own and on such occasions had to borrow them from someone else in the family. Because Kirsten was not a member of the nobility, it was unthinkable
that she could accompany Tycho to a royal celebration.

Tycho’s earlier career choices had been unorthodox and had led him into astronomy. Now, unwittingly and many years before anyone could predict how it would all end, he had made a decision that would have repercussions far beyond his own lifetime, his own children, and the borders of Denmark. When Tycho took Kirsten Jørgensdatter as his
life partner and began to sire children by her, he set his feet much more firmly on the path that would lead to Prague and to Johannes Kepler.

A plaque on an exterior wall at Herrevad commemorates an astronomical event late that same year that also gave Tycho a powerful push toward that future. The plaque announces:
HERE TYCHO BRAHE, ON THE EVENING OF NOVEMBER 11, 1572, DISCOVERED A “NEW STAR.”

It was a clear autumn evening after several days of overcast skies. Tycho, now nearly twenty-six, was walking back to supper from his alchemy laboratory, glancing up at the familiar darkening sky as he went. To his astonishment, right over his head, near the three stars that make up the right-hand half of the
W
of the constellation Cassiopeia, there was a star he had never seen before. “I knew
perfectly well—
⁶
for from my youth I have known all the stars in the sky, something which one can learn without difficulty—that no star had ever before existed in that place in the heavens,” Tycho wrote, “not
even
the very tiniest, to say nothing of a star of such striking clarity.” It was brighter than any other star or planet in the sky.

Not quite trusting his eyes, and wanting witnesses
to what he was seeing, Tycho called his servants and then stopped some peasants who were passing nearby. These people had not spent nights studying the stars as Tycho had, but they dutifully craned their necks to gaze up beyond the trees and the darkening walls, trying to oblige their noble companion by giving him an opinion as to whether or not this really was something new. They were not able to
confirm that this star had not been there before, but they did agree, when Tycho called their attention to Venus, that the new star was brighter even than that bright planet. “I doubted no longer,”
⁷
reported Tycho. “In truth, it was the greatest wonder that has ever shown itself in the whole of nature since the beginning of the world, or in any case as great as [when the] Sun was stopped by Joshua’s
prayers.”

Tycho realized that the star’s position in relation to the zodiac meant it could not be a planet, and, though he had never seen a comet, he knew from his reading that a comet has a tail and a fuzzy appearance. This had neither. However, the real test of whether it was a comet was whether it moved in relation to the other stars. Finding whether it did took several nights of watching,
armed with his cross staff. Tycho could not discern any change of position. This was no comet. Though more observation and calculation were needed to make certain, Tycho was also fairly confident that the new star was not closer to Earth than the Moon’s orbit—a dramatic conclusion in the context of the astronomy he knew. “Let all philosophers,
⁸
new as well as ancient, be silent! Let the very theologians,
interpreters of the divine mysteries, be silent! Let the mathematicians, describers of the heavenly bodies, be silent!” he exclaimed.

Aristotle’s ancient cosmology, which insisted that change could occur only in the region closer to Earth than the Moon’s orbit (the “sublunar” region), was still gospel among most scholars. Tycho had never declared himself an avid follower of Aristotelian cosmology,
but
he had not escaped its influence. However, it was in Tycho’s nature to want to test things out for himself. To do that, he had to try to measure the parallax shift of the new star, or
nova
, as he dubbed it.

Parallax shift is the apparent shift of an object against the background when observed from different viewing positions. The simplest demonstration is by holding one finger up in front
of your face, focusing on the distance, and closing first one eye and then the other. The finger appears to shift from side to side against the background. Your two eyes are the two “viewing positions.” The shift is a parallax shift. The further away you hold your finger from your face, the smaller the shift.

Though scholars had understood for millennia the mathematical principles of such
a shift and of the way it grows smaller with distance, determining the distance to a star by parallax was still impossible in Tycho’s day. Powerful enough telescopes would not exist until the 1830s. However, astronomers had known since ancient times that the Moon does have a parallax shift, that two observers a distance apart on the face of the Earth see the Moon in two different positions against
the background stars. An observer could even stay in the same place and allow the daily rotation of the celestial sphere (or the rotation of the Earth, if he believed Copernicus) to change his “viewing position” for him. If he did that (as Tycho had done), he saw for himself that the Moon did indeed have a parallax shift. A star or other object as close as the Moon, or closer, would also have a parallax
shift. And so, although it was not possible for Tycho to find the distance to the new star by means of a parallax measurement, it
was
possible for him to conclude that if this new object in the sky did not show any parallax shift against background stars, while the Moon
did
, it could not possibly be nearer than the Moon.