The Sleepwalkers
True to the family tradition, young Tyge was intended to take up the career of a statesman, and was accordingly sent at thirteen to study rhetorics and philosophy at the University of Copenhagen. But at the end of his first year, he witnessed an event which made an overwhelming impression on him and decided the whole future course of his life. It was a partial eclipse of the sun which, of course, had been announced beforehand, and it struck the boy as "something divine that men could know the motions of the stars so accurately that they were able a long time beforehand to predict their places and relative positions." 3 He immediately began to buy books on astronomy, including the collected works of Ptolemy for the considerable sum of two Joachims-Thaler. From now onward his course was set and he never swerved from it.
Why did that partial eclipse, which was not at all spectacular as a sight, have such a decisive impact on the boy? The great revelation for him, Gassendi tells us, was the predictability of astronomical events – in total contrast, one might speculate, to the unpredictability of a child's life among the temperamental Brahes. It is not much of a psychological explanation, but it is worth noting that Brahe's interest in the stars took from the beginning a quite different, in fact almost opposite direction from both Copernicus' and Kepler's. It was not a speculative interest, but a passion for exact observation. Starting on Ptolemy at fourteen, and making his first observation at seventeen, Tycho took to astronomy at a much earlier age than those two. The timid Canon had found a refuge from a life of frustrations in the secret elaboration of his system; Kepler resolved the unbearable miseries of his youth in his mystic harmony of the spheres. Tycho was neither frustrated nor unhappy, only bored and irritated by the futility of a Danish nobleman's existence among, in his own words, "horses, dogs and luxury"; and he was filled with naive wonder at the contrasting soundness and reliability of the stargazers' predictions. He took to astronomy not as an escape or metaphysical lifebelt, but rather as a full-time hobby of an aristocrat in revolt against his milieu. His later life seems to confirm this interpretation, for he entertained kings on his wonder island, but the mistress of the house, with whom he begot a large family of children, was a woman of low caste to whom he was not even married in church.
After three years at Copenhagen, the Vice-Admiral thought that it was time for Tyge to go to a foreign university, and sent him, accompanied by a tutor, to Leipzig. The tutor was Anders Soerensen Vedel, who later became famous as the first great Danish historian, translator of Saxo Grammaticus and collector of Nordic sagas. Vedel was then twenty, only four years older than his charge; he had received instructions to cure young Tyge of his unseemly preoccupation with astronomy and lead him back to studies more fitting for a nobleman. Tyge had bought a small celestial globe to learn the names of the constellations, but he had to hide it under his blanket; and when he added to this a cross-staff, he could use it only when his tutor was asleep. After a year of this, however, Vedel realized that Tyge was star-struck beyond remedy, gave in, and the two remained lifelong friends.
After Leipzig, Tycho continued his studies at the Universities of Wittenberg, Rostock, Basle and Augsburg until his twentysixth year, all the time collecting, and later designing, bigger and better instruments for observing the planets. Among these was a huge quadrant of brass and oak, thirty-eight feet in diameter and turned by four handles – the first of a series of fabulous instruments which were to become the wonder of the world. Tycho never made any epoch-making discovery except one, which made him the father of modern observational astronomy; but that one discovery has become such a truism to the modern mind that it is difficult to see its importance. The discovery was that astronomy needed precise and continuous observational data.
It will be remembered that Canon Koppernigk recorded only twenty-seven observations of his own in the whole Book of Revolutions; for the rest he relied on the data of Hipparchus, Ptolemy and others. This had been the general practice up to Tycho. It was taken for granted that planetary tables must be exact, as far as possible, for calendrical and navigational purposes; but apart from the limited data required for these practical reasons, the necessity for precision was not at all realized. This attitude, which is all but incomprehensible to the modern mind, was partly due to the Aristotelian tradition with its emphasis on qualities instead of quantitative measurement; within that mental framework only a crank could be interested in precision for precision's sake. Besides, and more specifically, a geometry of the skies consisting of cycles and epicycles did not require a great many, or even very precise, observational data, for the simple reason that a circle is defined when its centre and a single point of its circumference are known, or, if the centre is unknown, by three points of its circumference alone. Hence it was, by and large, sufficient to determine the positions of a planet at a few characteristic points of its orbit, and then to arrange one's epicycles and deferents in the way most favourable to "save the phenomena". If one projects one's mind back to the other side of the watershed, Tycho's devotion to measurements, to fractions of minutes of arc, appears as highly original. No wonder that Kepler called him the Phoenix of Astronomy.
On the other hand, if Tycho was ahead of his time, he was only a step ahead of Kepler. We have seen how Kepler was pining for Tycho's observations, for precise data on mean distances and eccentricities. A century earlier, Kepler would probably have rested on the laurels of his solution of the cosmic mystery without bothering about those small disagreements with observed facts; but this metaphysical cavalier-attitude towards facts was on the wane among the advanced minds of the time. Ocean navigation, the increasing precision of magnetic compasses and clocks, and the general progress in technology created a new climate of respect for hard fact and exact measurement. Thus, for instance, the debate between the Copernican and Ptolemaic systems was no longer pursued by theoretical arguments alone; both Kepler and Tycho independently decided to let experiment be the arbiter, and tried to determine by measurement whether a stellar parallax existed or not.
One of the reasons for Tycho's quest for precision was, in fact, his desire to check the validity of the Copernican system. But this was perhaps rather the rationalization of a deeper urge. Meticulous patience, precision for precision's sake was for him a form of worship. His first great experience had been the awestricken realization that astronomic events could be exactly predicted; his second was of the opposite kind, On 17 August, 1563, at the age of seventeen, while Vedel was asleep, he noticed that Saturn and Jupiter were so close together as to be almost indistinguishable. He looked up his planetary tables and discovered that the Alphonsine tables were a whole month in error regarding this event, and the Copernican tables by several days. This was an intolerable and shocking state of affairs. If the stargazers, of whose low company his family so disapproved, could not do better, let a Danish nobleman show them how a proper job is done.
And show them he did, by methods and gadgets the like of which the world had never seen.
2. The New Star
At the age of twenty-six, Tycho considered his education complete, and returned to Denmark. For the next five years, till 1575, he lived first on the family estate at Knudstrup, then with an uncle, Steen Bille, the only one in the family who approved of Tycho's perverse hobby. Steen had founded the first paper mill and glassworks in Denmark, and dabbled a lot in alchemy in which Tycho assisted him.
Like Kepler, Tycho stood with one foot in the past and was devoted both to alchemy and astrology. Like Kepler, he became a court astrologer and had to waste much of his time with the casting of horoscopes for patrons and friends; like Kepler, he did it with his tongue in his cheek, despised all other astrologers as quacks, and yet was profoundly convinced that the stars influenced man's character and destiny though nobody quite knew how. Unlike Kepler's, however, his belief in astrology derived not from mysticism – which was completely alien to his domineering nature – but from stark superstition.
The great event of these years, an event that was discussed all over the
world and which established, at a single stroke, Tycho's fame as the leading astronomer of his time, was the new star of 1572. In Tycho's life, all the decisive landmarks were sky-marks: the eclipse of the sun when he was fourteen which brought him to astronomy, the conjunction of Jupiter and Saturn when he was seventeen, which made him realize its insufficiencies; the new star when he was twenty-six, and the comet of 1577, five years later. Of all these, the new star was the most important.
On the evening of 11 November, 1572, Tycho was walking from Steen's alchemist laboratory back to supper when, glancing at the sky, he saw a star brighter than Venus at her brightest, in a place where no star had been before. The place was a little to the north-west of the familiar "W" – the constellation of Cassiopeia, which then stood near the Zenith. The sight was so incredible that he literally did not believe his eyes; he called at first some servants, and then several peasants to confirm the fact that there really was a star where no star had any business to be. It was there all right, and so bright that later on people with sharp eyes could see it even in the middle of the day. And it remained in the same spot for eighteen months.
Other astronomers besides Tycho had seen the new star in the first days of November. It was then in full blaze; in December it began very slowly to fade, but ceased to be visible only by the end of March, the year after next. The world had never seen or heard the like since the year 125 B.C. when Hipparchus, according to the second book of Pliny's Natural History, had seen a new star appear in the sky.
The sensational importance of the event lay in the fact that it contradicted the basic doctrine – Aristotelian, Platonic and Christian – that all change, all generation and decay were confined to the immediate vicinity of the earth, the sub-lunary sphere; whereas the distant eighth sphere in which the fixed stars were located, was immutable from the day of Creation to eternity. The only known exception in history was the appearance of the above-mentioned new star of Hipparchus; but that had been very long ago, and one could explain it away by assuming that Hipparchus had merely seen a comet (which was then considered an atmospheric phenomenon in the sub-lunary region).
Now, what distinguishes a fixed star from a planet, or a comet, or a meteor, is the fact that it is "fixed": apart from its participation in the daily rotation of the firmament as a whole, it does not move. No sooner did that bright new cuckoo egg appear on the tip of the celestial "W", far out-shining the legitimate stars in its nest, stargazers all over Europe feverishly tried to determine whether it moved or not. If it did, it was not a real star and academic science was saved; if it did not, the world had to be thought afresh.
Maestlin in Tuebingen who, though one of the leading astronomers of the time, seems to have possessed no instruments whatsoever, held a thread at arm's length from his eyes in such a way that it passed through the new star and two other fixed stars. When, after a few hours, the three were still in the same straight line, he concluded that the new star did not move. 4 Thomas Digges in England used a similar method, and came to the same result; others found a displacement, but only a small one, due, of course, to the errors of their coarse instruments. This was Tycho's great opportunity, and he fully rose to it. He had just finished a new instrument – a sextant with arms five and a half feet long, joined by a bronze hinge, with a metallic arc scale graduated to single minutes and, as a novelty, a table of figures designed to correct the errors of the instrument. It was like a heavy gun compared to the slings and catapults of his colleagues. The result of Tycho's observations was unequivocal: the new star stood still in the sky.
All Europe was agog, both with the cosmological and astrological significance of the event. The new star had appeared only about three months after the massacre of French protestants on St. Bartholomew's night; no wonder that in the flood of pamphlets and treatises on the star, it was mostly regarded as a sinister omen. The German painter, George Busch, for instance, explained that it was really a comet condensed from the rising vapours of human sins, which had been set afire by the wrath of God. It created a kind of poisonous dust (rather like the fall-out from a Hydrogen bomb) which was drifting down on people's heads and caused all sorts of evil, such as "bad weather, pestilence, and Frenchmen". The more serious astronomers, with few exceptions, tried to explain the star away from the eighth sky by calling it a tailless comet, ascribing to it a slow motion, and using other subterfuges which made Tycho contemptuously talk of O, coecos coeli spectatores – oh, blind watchers of the sky.
The next year, he published his first book: De Nova Stella.
He hesitated some time before publishing it, because he had not yet quite overcome the idea that the writing of books was an undignified occupation for a nobleman. The book is a hodgepodge of tedious prefatory letters, calendrical and meteorological diaries, astrological predictions and versified outpourings, including an eight-page "Elegy to Urania"; but it contained in twenty-seven pages an exact description of Tycho's observations of the New Star, and of the instrument with which the observations were made – twenty-seven pages of "hard, obstinate facts", which alone would suffice to establish his lasting fame.
Five years later, he gave Aristotelian cosmology the coup de grâce, by proving that the great comet of 1577 was also not a sublunary phenomenon, as comets had previously been regarded, but must be "at least six times" as far in space as the moon.
About the physical nature of the new star, and how it was created, Tycho wisely professed ignorance. Contemporary astronomy calls "new stars" novae, and explains their sudden increase in brightness by an explosive process. There had doubtless been other novae between 125 B.C. and A.D. 1572; but man's new consciousness of the sky, and the new attitude to precise observation, gave the star of 1572 a special significance: the explosion which caused its sudden flaring up shattered the stable, walled-in universe of the ancients.
3. Sorcerer's Island
King Frederick II of Denmark, whose life had been saved by Tycho's foster-father, the late Vice-Admiral, was a patron of philosophy and the arts. When Tycho was still a student of twentyfour, the King's attention had been called to the brilliant young man, and he had promised him, as a sinecure, the prebend from the first canonry to become vacant. In 1575, when his reputation was already established, Tycho, who loved travelling and did it like everything else in the grand style, made a tour of Europe, visiting friends, mostly astronomers, in Frankfurt and Basle, Augsburg, Wittemberg, and Venice, among them the Landgraf Wilhelm IV in Cassel. The Landgraf was more than an aristocratic dilettante. He had built himself an observatory on a tower in Cassel, and was so devoted to astronomy that, when told that his house was on fire while he was observing the new star, he calmly finished his observation before giving his attention to the flames.
He and Tycho got on so well that, after the visit, the Landgraf urged King Frederick to provide Tycho with the means for building his own observatory. When Tycho returned to Denmark, Frederick offered him various castles to choose from; but Tycho declined because he had set his heart on taking up residence in Basle, the charming and civilized old town which had captured the love of Erasmus, Paracelsus, and other illustrious humanists. Now Frederick became really eager to preserve Tycho for Denmark, and in February '76, sent a messenger – a youth of noble birth with orders to travel day and night – bearing a royal order for Tycho to come and see the King at once. Tycho obeyed, and the King made him an offer that sounded like a fairy tale: an island in the Sund between Copenhagen and Elsinor Castle, three miles in length, extending over two thousand acres of flat tableland rising on sheer white cliffs out of the sea. Here Tycho should build his house and observatory at Denmark's expense, and in addition receive an annual grant, plus various sinecures, which would make his income one of the highest in Denmark. After a further week's hesitation, Tycho graciously accepted the island of Hveen, and the fortune that went with it.
Accordingly, a royal instrument, signed on 23 May, 1576, decreed that:
"We, Frederick the Second, &c., make known t
o all men, that we of our special favour and grace have conferred and granted in fee, and now by this our open letter confer and grant in fee, to our beloved Tyge Brahe, Otto's son, of Knudstrup, our man and servant, our land of Hveen, with all our and the crown's tenants and servants who thereon live, with all rent and duty which comes from that, and is given to us and to the crown, to have, use and hold, quit and free, without any rent, all the days of his life, and as long as he lives and likes to continue and follow his studia mathematices..." 5
Thus came into existence the fabulous Uraniburg on the island of Hveen, where Tycho lived for twenty years and taught the world the methods of exact observation.
Tycho's new domain, which he called "the island of Venus vulgarly named Hveen", had an old tradition of its own. It was often referred to as the "Scarlet Island" – for reasons which a sixteenth century English traveller explains in his account:
"The Danes think this Island of Wheen to be of such importance, as they have an idle fable, that a King of England should offer for the possession of it, as much scarlet cloth as would cover the same, with a Rose-noble at the corner of each cloth." 6
It also had some thirteenth century ruins, to which Danish folklore attached a Niebelung saga all of its own. Its inhabitants, distributed over some forty farms grouped around a small village, became Tycho's subjects, who lorded over them like an oriental despot.