Tycho Brahe 1546–1601
Danish astronomer and poet.
An outstanding and influential sixteenth-century astronomer, Tycho Brahe is esteemed mostly for his comprehensive study of the visible planets and stars which announced the era of modern, scientific astronomy. An intermediate between the commanding figures of Nicolaus Copernicus and Johannes Kepler, Brahe devised a cosmological system that blends a degree of Copernican planetary mechanics with his own meticulous and exhaustive observations. Unwilling to abandon the centuries-old geocentric scheme as Copernicus had, Brahe nevertheless made significant advances in the technique of astronomical inquiry, and is credited with applying the scientific method of repeated experimentation and observation to the art of astronomy. In addition, his remarkable and detailed accounts of a new star (supernova) in the constellation of Cassiopeia, and of the comet of 1577 led some scholars to suggest that Brahe was among the first to offer incontrovertible evidence against the Church-sanctioned, Aristotelian belief in solid celestial spheres and a permanent, unchanging firmament.
Brahe was born in December 1546 in Knudstrup, a town in the Scania region of southern Sweden (then controlled by Denmark), into a prosperous aristocratic Danish family. At an early age he was taken into the care of an uncle, who raised Brahe to adulthood and provided liberally for his education. In 1559 the youthful Brahe began the study of law at the University of Copenhagen, but soon discovered that his true interests lay in the field of astronomy. While pursuing his law studies, Brahe devoted his attention skyward and was introduced to the Almagest of Claudius Ptolemy, the dominant astronomical text since classical antiquity. In 1562, Brahe left Copenhagen for the University of Leipzig to further his education in astronomy. The following year, Brahe's observations of Jupiter and Saturn convinced him of the inaccuracy of the current, Copernican tables of planetary, solar, and stellar positions—a situation that Brahe spent the remainder of his life trying to rectify. In 1565, Brahe departed from Leipzig and continued his education in mathematics and astronomy at Wittenburg, Augsburg, and other eminent universities. By the early 1570s he had inherited funds from both his father and uncle, and
took to observing the nighttime skies in his native Scania. On November 11, 1572, Brahe witnessed one of the defining celestial events of his career, the light of a new star—produced by what modern astronomers call a supernova—in the constellation of Cassiopeia. His detailed account of this phenomenon—which had been perceived by others who, however, failed to record the event with the same comprehensive accuracy as Brahe—guaranteed him a rising reputation in the European scientific community.
Brahe's publication of De nova stella (1573) and continued astronomical work impressed King Frederick II of Denmark, who granted him the small Danish islandfief of Hven (now Ven) in 1576. With the continued support of Frederick II, Brahe undertook the construction of an observatory on Hven he would name Uranibourg. Drawing a small but thriving community of young mathematician-astronomers to Hven, Uranibourg provided Brahe with the means to accomplish his goal of cataloging the visible stars, and to more accurately update calculations of their positions, as well as those of the sun, moon, and known planets. Uranibourg was additionally the site of many discoveries, most importantly Brahe's observation of the comet of 1577, the impetus for his crowning astronomical treatise entitled De mundi aetherei recentioribus phaenomenis liber secundus qui est de illustri Stella caudata, published in 1588. King Frederick II's death that same year and the subsequent decreases in Brahe's income over the next decade forced the astronomer from Hven in 1597. Searching for patronage on the continent, he eventually settled in Prague under the support of Emperor Rudolf II in 1599. He died in Bohemia in 1601.
The title of Brahe's earliest astronomical work of note, De nova stella, suggests its subject, the new star or supernova he witnessed in November of 1572. A decade and a half later, Brahe produced what scholars agree is his most significant work of astronomy, his De mundi. Ostensibly concerned with the comet of 1577, the work's eighth chapter, however, contains the astronomer's first detailed presentation of his theory of planetary cosmology, the Tychonic system, developed between the years 1583 and 1588. While Brahe believed that he had created a revolutionary cosmology, modern critics acknowledge that his system amounts to something of a compromise between the earth-centered Ptolemaic scheme of antiquity and the heliocentric system of Nicolaus Copernicus's De revolutionibus (1543). Believing that the Copernican system with its moving earth defied the laws of physics, Brahe devised a geocentric organization of the solar system. In the Tychonic system, the sun and moon are represented as orbiting the earth—as Ptolemy had shown them to do in his Almagest, and as most astronomers believed until the seventeenth century—while the remaining five planets then known (Mercury, Venus, Mars, Jupiter, and Saturn) are placed in everlarger orbits around the sun, as Copernicus had theorized decades before. The remaining nine chapters of the De mundi are devoted to Brahe's observations on the size, composition, and behavior of comets—by far the most comprehensive and accurate treatment of the subject in the sixteenth century—as well as his observations of the work of previous and contemporary astronomers concerning these celestial objects. Brahe's other writings include his lengthy Astronomiae instauratae progymnasmata (1602) and Astronomiae instauratae mechanica (1598). The former includes Brahe's catalogue of 777 stars as well as his solar and lunar theories, the latter details the many innovative astronomical instruments he designed over the course of his career. Brahe's collected works, comprising his correspondence and poetry as well as his scientific writings, have been accumulated in the fifteen volumes of Opera omnia Tychonis Brahe Dani (1913-1929). Among many other writings—the majority of them previously unpublished or privately printed—this collection contains the representative poem Urania Titani, a verse epistle in the style of Ovid which is based on the love affair of Brahe's sister Sophie and her fiancé, Brahe's sometime colleague, Erik Lange.
The overall assessment of Brahe's contribution to astronomy lies less in the details of his planetary system than in the scientific ideals and methods he pursued. Thus, scholars have been quick to point out that Brahe's earth-centered system does not represent a dramatically counterproductive step away from the Copernican heliocentric cosmology proposed more than four decades prior. Brahe, they have argued, by incorporating something of the Copernican scheme into his earth-centered system and supporting it with extensive observational data (as Copernicus had not) laid a great deal of the groundwork for a successful, inductive demonstration of the true nature of the solar system. Additionally, commentators have noted that Brahe's accumulated data of stellar and planetary motion, passed on to his student and assistant Johannes Kepler, offered the German mathematician the raw material he needed to develop his laws of planetary motion. Finally, Brahe's work on the new star of 1572 and comet of 1577 have generally been regarded as important evidence that presaged Galileo Galilei's dismantling of the traditional Aristotelian cosmology of solid celestial spheres in the early seventeenth century.