Tycho Brahe (1546-1601)
Tyge (Latinized as Tycho) Brahe was born on 14 December 1546 in Skane, then in Denmark, now in Sweden. He was the eldest son of Otto Brahe and Beatte Bille, both from families in the high nobility of Denmark. He was brought up by his paternal uncle Jörgen Brahe and became his heir. He attended the universities of Copenhagen and Leipzig, and then traveled through the German region, studying further at the universities of Wittenberg, Rostock, and Basel. During this period his interest in alchemy and astronomy was aroused, and he bought several astronomical instruments. In a duel with another student, in Wittenberg in 1566, Tycho lost part of his nose. For the rest of his life he wore a metal insert over the missing part. He returned to Denmark in 1570.
In 1572 Tycho observed the new star in Cassiopeia and published a brief tract about it the following year. In 1574 he gave a course of lectures on astronomy at the University of Copenhagen. He was now convinced that the improvement of astronomy hinged on accurate observations. After another tour of Germany, where he visited astronomers, Tycho accepted an offer from the King Frederick II to fund an observatory. He was given the little island of Hven in the Sont near Copenhagen, and there he built his observatory, Uraniburg, which became the finest observatory in Europe.
Uraniburg
Sextant Mural Quadrant
Tycho designed and built new instruments, calibrated them, and instituted nightly observations. He also ran his own printing press. The observatory was visited by many scholars, and Tycho trained a generation of young astronomers there in the art of observing. After a falling out with King Christian IV, Tycho packed up his instruments and books in 1597 and left Denmark. After traveling several years, he settled in Prague in 1599 as the Imperial Mathematician at the court of Emperor Rudolph II. He died there in 1601. His instruments were stored and eventually lost.
Tycho's major works include De Nova et Nullius Aevi Memoria Prius Visa Stella ("On the New and Never Previously Seen Star) (Copenhagen, 1573); De Mundi Aetherei Recentioribus Phaenomenis ("Concerning the New Phenomena in the Ethereal World) (Uraniburg, 1588); Astronomiae Instauratae Mechanica ("Instruments for the Restored Astronomy") (Wandsbeck, 1598; English tr. Copenhagen, 1946); Astronomiae Instauratae Progymnasmata ("Introductory Exercises Toward a Restored Astronomy") (Prague 1602). His observations were not published during his lifetime. Johannes Kepler used them but they remained the property of his heirs. Several copies in manuscript circulated in Europe for many years, and a very faulty version was printed in 1666. At Prague, Tycho hired Johannes Kepler as an assistant to calculate planetary orbits from his observations. Kepler published the Tabulae Rudolphina in 1627. Because of Tycho's accurate observations and Kepler's elliptical astronomy, these tables were much more accurate than any previous
Tycho Brahe's contributions to astronomy were enormous. He not only designed and built instruments, he also calibrated them and checked their accuracy periodically. He thus revolutionized astronomical instrumentation. He also changed observational practice profoundly. Whereas earlier astronomers had been content to observe the positions of planets and the Moon at certain important points of their orbits (e.g., opposition*, quadrature *, station), Tycho and his cast of assistants observed these bodies throughout their orbits. As a result, a number of orbital anomalies never before noticed were made explicit by Tycho. Without these complete series of observations of unprecedented accuracy, Kepler could not have discovered that planets move in elliptical orbits. Tycho was also the first astronomer to make corrections for atmospheric refraction*. In general, whereas previous astronomers made observations accurate to perhaps 15 arc minutes, those of Tycho were accurate to perhaps 2 arc minutes, and it has been sh
Tycho's observations of the new star of 1572 and comet of 1577, and his publications on these phenomena, were instrumental in establishing the fact that these bodies were above the Moon and that therefore the heavens were not immutable as Aristotle had argued and philosophers still believed. The heavens were changeable and therefore the Aristotelian division between the heavenly and earthly regions came under attack (see, for instance, Galileo's Dialogue) and was eventually dropped. Further, if comets were in the heavens, they moved through the heavens. Up to now it had been believed that planets were carried on material spheres (spherical shells) that fit tightly around each other. Tycho's observations showed that this arrangement was impossible because comets moved through these spheres. Celestial spheres faded out of existence between 1575 and 1625.
If Tycho destroyed the dichotomy between the corrupt and ever changing sublunary world and the perfect and immutable heavens, then the new universe was clearly more hospitable for the heliocentric planetary arrangement proposed by Nicholas Copernicus in 1543. Was Tycho therefore a follower of Copernicus? He was not. Tycho gave various reasons for not accepting the heliocentric theory, but it appears that he could not abandon Aristotelian physics which is predicated on an absolute notion of place. Heavy bodies fall to their natural place, the Earth, which is the center of the universe. If the Earth were not the center of the universe, physics, as it was then known, was utterly undermined. On the other hand, the Copernican system had a number of advantages, some technical (such as a better lunar theory and smaller epicycles), and others more based on harmony (an obvious explanation of retrograde planetary motion *, a strict demonstration of the order and heliocentric distances of the planets). Tycho developed
The Tychonic Universe. High-resolution image also available.
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Sources
The standard biography of Tycho Brahe is Victor E. Thoren, The Lord of Uraniborg: A Biography of Tycho Brahe (Cambridge: Cambridge University Press, 1990). Still useful is the more technical treatment by J. L. E. Dreyer, Tycho Brahe: A Picture of Scientific Life and Work in the Sixteenth Century (Edinburgh: Adam & Charles Black, 1890; 2d ed. New York: Dover, 1963). C. Doris Hellman's article in the Dictionary of Scientific Biography is also useful. Tycho's works and correspondence have been collected in Tychonis Brahe Dani Opera omnia, ed. J. L. E. Dreyer, 15 vols. (Copenhagen 1913-1929; reprinted Amsterdam: Swets & Zeitlinger, 1972). See also John Christianson, "The Celestial Palace of Tycho Brahe," Scientific American, 204, no. 2 (1961):118-128; Charles D. Humberd, "Tycho Brahe's Island," Popular Astronomy, 45 (1937):118-125; Joseph Ashbrook, "Tycho Brahe's Nose," Sky and Telescope, 29, no. 6 (1965):353, 358; C. Doris Hellman, "Was Tycho Brahe as Influential as He Thought?" British Journal for the History
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Glossary terms
opposition -- The situation of two heavenly bodies when their longitudes or right ascensions differ by 180 degrees. The moon is in opposition to the sun when the earth is directly between them.
quadrature -- Those points or moments at which a half moon is visible. More generally, it is the situation of two heavenly bodies when their longitudes differ by 90 degrees.
atmospheric refraction -- The change in direction of a ray of light as it passes from space into the atmosphere. This causes celestial objects to appear to be in a location different from their actual ones.
retrograde planetary motion -- At times, the planets appear to be moving opposite to their normal direction of motion. This is an effect caused by the annual motion of the Earth around the Sun which is superimp-osed on the motion of the plent.
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Images:
Sextant: From Tycho Brahe's Description of his Instruments and Scientific Work, tr. Hans Ręder et al, Copenhagen: Munksgaard, 1946), p. 72.
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Copyright ©1995 Albert Van Helden
'The Noble Dane' was one of several epithets applied to the sixteenth-century astronomer Tycho Brahe by the first Astronomer Royal, John Flamsteed. Pierre Gassendi, in the first biography of Tycho published in 1654, had already referred to him as 'nobilis Danus'. Nobility was the quality most commonly attributed to Tycho. He was indeed a member of a Danish noble family, but it was not mere lineage that gave Tycho his lasting image. He practised astronomy in a princely manner and on a grand scale.
Although Tycho benefited from the generous patronage of Frederick II, notably through the use and revenues of the island of Hven, he did not serve the King in the traditional manner of the court astronomer. Rather Tycho ruled his island as a fiefdom and the apt title of a recent biography is The Lord of Uraniborg - the name he gave to the 'Heavenly Castle' he built on Hven.
Here and in a second observatory building, Stjerneborg or 'Starry Castle', Tycho erected a remarkable range of instruments for astronomical measurement, from armillary spheres after the manner of Ptolemy to large quadrants of bold and original design. His instruments were built in his own workshops and his books printed on his own presses. With the help of an extensive staff of assistants he carried out an ambitious programme of work, effectively re-establishing the observational basis of astronomy.
Small wonder that Tycho was an object of admiration and emulation. He was held in enormous respect by generations of astronomers. While there is no doubt that his achievements gave him a special place in the history of astronomy, he fashioned his own image in a striking and individual manner. Tycho did more to construct an image of himself in the view of others that any other astronomer of his time, perhaps of any time. His whole programme was so comprehensive, audacious and individual that it seems inseparable from its author. He published a detailed account of his observatory and instruments in a book, Astronomiae instauratae mechanica, that became a model for others and that abounds with personal references and assertions. The most abiding image of Tycho and one of the most famous images in the history of astronomy comes from the fresco he had painted on the wall that carried the instrument he named after himself, the Tyconian Quadrant.
Tycho's grand and emphatic self-presentation may sit uneasily with the image of him offered in the picture by Ender, where he performs a more traditional courtly service before a patron whose attention is less than complete. By the time of this scene, Tycho had lost favour in Denmark and had been obliged to seek patronage elsewhere. Although Rudolph was keen to accommodate this prominent addition to his entourage, Tycho's situation was much more constrained than it had been on Hven.
Tycho, however, was careful to raise his work above such wordly concerns. Linking nobility with astronomy itself, he wrote in the Mechanica that: 'the person who cultivates divine Astronomy ought not to be influenced by ignorant judgements, but rather look upon them from his elevated position, considering the cultivation of his studies the most precious of all things, and remaining indifferent to the coarseness of others. And when statesmen or others bother him too much, then he should leave with his possessions.'