(Adapted from Tycho Brahe: A Picture of Scientific Life)
The Revival of Astronomy in Europe
The early part of the 16th century must always be ranked among the most remarkable periods in te history of civilization. The invention of printing made literature the property of many to whom it had been inaccessible, and the downfall of the Byzantine Empire had scattered over Europe a number of fugitive Greeks, who carried with them many treasures of classical literature unknown in the western world. Meanwhile, Rafael, Michelangelo and their contemporaries revived the glory of the ancients in the realm of art.
During this active period there were also signs of renewed vigor among the devotees of science, and the time was particularly favorable to a revival of astronomical studies. The students of astronomy were now able to study the Greek authors in the original language instead of having to be content with Latin reproductions of Arabian translations from the Greek. Another impulse was given by the voyages of discovery, as navigators worldwide were obliged to trust entirely into the stars and the compass, and therefore required as perfect in theory as possible of the motions of the heavenly bodies. Accordingly, we see at the end of the 15th century and in the beginning of the 16th a considerable stir in science, but as yet only in Germany.
The first noteworthy astronomer was Georg Purbach (1423-61), who study at the University of Vienna and afterwards for some time in Italy. His principal work on astronomy attempted to develop the old hypotheses of material celestial spheres, and it was a mixture of Aristotelian cosmology and Ptolemean geometry. And he was the first European to make use of trigonometry, the principal legacy which astronomers owed to the Arabs. Purbach endeavored to get beyond the rudiments of spherical astronomy, which before had formed the only subject for astronomical lectures, and had been taught by the medium of a treatise written in the 13th-century by John Holywood for use at the University of Paris.
While lecturing in Vienna, Purbach’s attention was drawn to a young disciple of great promise, Johann Müller, from Konigsberg, a small village in Franconia, where he was born in 1436. He entered with heart and soul into his teacher’s studies of the great work of Ptolemy, which embodied all the results of Greek astronomy, and he soon became an invaluable cooperator to Purbach. They did not confine themselves to theoretical studies but, with the crude instruments as they could construct, they convinced themselves of the fact that the places of the planets computed from the astronomical tables of King Alfonso X differed considerably from the actual positions of the plants in the sky.
In the midst of this, the two astronomers had the good luck to become acquainted with Cardinal Bassarion, a Greek by birth, who was the Bishop of Nicaea. The translation of the original Almagest (as Ptolemy’s work was generally called) was a subject in which he was particularly interested in and during his stay in Vienna he succeeded in communicating to Purbach his own anxiety to make Ptolemy better known in the scientific world. Purbach was about to head off for Italy for the purpose of collecting Greek manuscripts when he died suddenly in 1461. Muller succeeded to his place in the Cardinal’s friendship and set out for Italy with Bassarion in the following year.
Muller stayed in Italy about seven years, losing no chance to study the Greek language and collecting Greek manuscripts. In Venice he wrote a treatise on trigonometry, which he continued to develop for the remainder of his life. After his return to Germany, in 1471, he settled in Nürnberg. This city was one of the chief centers of German industry and literary life and nowhere did the higher classes of citizens use their wealth so willingly in the support of art and science. The new art of printing had recently been introduced at Nürnberg — a circumstance of particular importance to the collector of Greek writings.
A wealthy citizen, Bernhard Walther, became friends of Müller and Bassarion arranged an observatory for their joint use. Instruments, as fine as the skillful artisans of Nürnberg could produce, adorn the earliest European observatories, and the two friends made good use of them: they observed the comment of 1472 and originated several new methods of observing. But Müller did not forget the printing operations and published not only Purbach’s Theoricæ Nova trigonometrical tables, but also his own celebrated Ephemerides, the first of their kind, which some years later were made known to navigators and guided Diaz, Columbus, Vasco de Gama and many others safely across the ocean.
Müller suddenly died in 1476 at the age of 40, but he rendered a great service to science, not only by his endeavors to save the Greek authors from oblivion, but also by his Ephemerides, his development of trigonometry and his observations.
By Purbach and Müller the astronomy of the Alexandrian school had been introduced at the German universities and the increased demands by navigators continued to help forward the study of astronomy in Germany.
Of the astronomers who worked during the first half of the 16th-century, Bienewitz should be mentioned. Besides other works, in 1540 he published a large book, Astronomicum Cæsareum, dedicated to Charles V. In this beautiful volume he, by means of movable circles of cardboard of various colors, depicted the epicyclical motions of the planets according to the Ptolemean system and in this way the expected positions of the planets could be found without computation.
1543 saw the appearance of the great work of Nicholas Copernicus, De Revolutionibus, which was destined to become the cornerstone of modern astronomy. Copernicus was born in 1473 in Thorn, Poland, and first studied at the University of Kraków, where astronomy was specially cultivated. At age 24 he went to Bologna, where he studied under Domenico Maria Novara. Thus he not only became acquainted with Ptolemy’s work, but also acquired some familiarity with the astronomical circle, one of the few crude instruments then in use.
Regrettably, we are unacquainted with the manner in which Copernicus came to design the new system of astronomy which has made his name immortal. But probably he had perceived that, however valuable the labors of Müller have been, they have not improved the theory of celestial motion, so that the most important problem, that would have computing before hand positions of the planets and accounting was practically untouched since the days of Ptolemy.
Copernicus had completed an extended the planetary system of Hipparchus, and in an ingenious way represented the complicated phenomena. But more than 1400 years had passed since his time and the system, however perfect from a mathematical point of view, had long been felt to be too complicated and not agreeing closely enough with the observed movements of the planets.
This circumstance led Copernicus to attempt the construction of a new system, founded on the idea that the sun, not the earth, is the ruler of the planets. But Copernicus was unable to do more then to demonstrate the possibility of explaining the phenomenon by starting from the heliocentric idea. Having no materials from which to deduce the true laws of the motion of the planets in elliptic orbits, he was obliged to make use of the eccentric circles and epicycles of the ancients, by which he greatly marred the beauty and simplicity of his system. He did not possess accurate instruments, and took a few observations with those he had. The idea does not seem to have struck him that it was indispensable to follow the planets through a number of years with carefully constructed instruments, and only in that way could the true theory of planetary motion be found.
There was much to be done before the reform of astronomy could be accomplished. The pressing need for new tables was supplied a few years after the death of Copernicus by Erasmus Reinhold, but though the positions of the planets could be computed from that with greater accuracy then from the old tables, the “Prutenic tables” (published in 1551) did not buy this superiority offer any proof of the actual truth of the Copernican principle.
A century had elapsed since the study of astronomy has been revived in Italy and Germany, but as yet the work accomplished had chiefly been of a tentative and preparatory nature, with Copernicus alone having attempted to make science advanced along a new path. Still, much useful work was done. The labors of the ancients became accessible in the originals; the Arabs and Muller had developed trigonometry, and thereby facilitated astronomical computations; Copernicus had shaken the implicit conviction of the necessity of clinging to the complicated Ptolemean System, and had offered the world ample alternatives and a simpler system, with new tables having been computed to replace the Alphonsine tables.
But otherwise the astronomy of the ancients reigned undisturbed. No advances were made in the knowledge of the positions of the fixed stars, those stations in the sky by means of which the motions of the planets had to be followed. Further, the value of almost every astronomical quantity had to be borrowed from Ptolemy, except for a few which is been redetermined by the Arabs. No advance have been made in the knowledge of the moon’s motion, so important for navigation, nor in the knowledge of the nature of the planetary orbits, to uniform circular motion being still thought not only the most perfect, but also the only possible one for the planets to pursue.
Whether people believe the planets to move around the earth or around the sun, the complicated machinery of the ancients had to be employed in computing their motions, and crude as the instruments and use word, they were more than sufficient to show that the best planetary tables could not foretell the positions of the planets with anything like the desired accuracy.
As yet, no astronomer had made up his mind to take nothing for granted on the authority of the ancients. No one had perceived that the answers to the many questions that were perplexing astronomers could only be given by the heavens, but that the answers would be forthcoming only if the heavens were properly interrogated by means of improved instruments, capable of determining every astronomical quantity a new anew systemic observations. At early age, Tycho Brahe perceived the necessity of doing all this. By his labors he supplied a firm foundation for modern astronomy and gave his successor, Kepler, the means of completing the work commenced by Copernicus.
The Advent of Tycho Brahe
Danish astronomer Tycho Brahe made the most accurate celestial observations of his time and challenged the prevailing belief in how the universe was organized. And while most people may think of scientists as stodgy academic types, Brahe's flamboyant lifestyle and ignominious death would have made some of today's wild celebrities look like choirboys.
A colorful life
Born in Denmark in 1546, Brahe's parents were members of nobility. He was raised by his wealthy uncle, and attended universities in Copenhagen and Leipzig. Though his family badgered him to study law, Brahe chose instead to pursue astronomy.
In 1566, 20-year-old Brahe fought a fellow student in a duel over who was the better mathematician. As a result, he lost a large chunk of his nose. For the rest of his life, he donned a metal prosthetic to cover the disfigurement.
A precise view of the heavens
Despite his colorful life and death, Brahe contributed significantly to the field of astronomy. At the time, astronomers held to the idea that the heavens were composed of separate individual spheres, with everything revolving around the Earth.
The New Star of 1572
On the evening of the 11th November 1572, Tycho Brahe had spent some time in the laboratory, and was returning to the house for supper, when he happened to throw his eyes up to the sky, and was startled by perceiving an exceedingly bright star in the constellation of Cassiopeia, near the zenith, and in a place which he was well aware had not before
been occupied by any star. Doubtful about whether he was to believe his own eyes, he turned round to some servants who accompanied him and asked whether they saw the star; and though they answered in the affirmative, he called out to some peasants who happened to be driving by, and asked the same question from them.
When they also answered that they saw a very bright star in the place he indicated, Tycho could no longer doubt his senses, so he at once prepared to determine the position of the new star. He had just finished making a new instrument, a sextant similar to the one he had made for Paul Hainzel, and he was therefore able to measure the distance of the new star from the principal stars in Cassiopeia with greater accuracy than the cross-staff would have enabled him to attain.
With this instrument, Tycho measured the distance of the star from the nine principal stars of Cassiopeia. We can easily picture to ourselves the impatience with which he must have awaited the next clear night, in order to see whether this most unusual phenomenon would still appear, or whether the star should have vanished again as suddenly as it had revealed itself. But there the star was, and continued to be for about eighteen months, north of the three stars which form the preceding part of the well-known W of this constellation, and forming a parallelogram with them.
It was only a degree and a half distant from a star ( K ) of the 4^- magnitude. While the star was visible, Tycho continued to measure its distance from the other stars of Cassiopeia; and in order to find whether it had any parallax, he repeated these measures from time to time during the night, and even left the sextant clamped in the interval between two observations, to make sure that no change had taken place in the instrument in the meantime.
The star being circumpolar for his latitude, he was able to follow it right round the pole, and he took advantage of this circumstance to observe its altitude at the lower culmination by the sextant, as he did not at that time possess a quadrant. He placed it in the plane of the meridian with the one arm, which we may call the fixed one, and to which he had now attached an arc of 60, resting horizontally on a window-sill and a short column inside the room.
To ensure the horizontal position of the arm, it was moved until a plumb-line suspended from the end of the graduated arc touched a mark exactly at the middle of the arm, and as the instrument might happen to be slightly moved while the observation was being made, a short graduated arc was traced at the middle of the arm, on which the plumb-line would immediately mark the small correction to be applied to the observed altitude. This simple but neat contrivance is highly characteristic of Tycho; we recognize here the modern principle of acknowledging an instrument to be faulty, and applying corrections for its imperfections to the results determined by it, a principle which we shall see he followed in the construction of all his instruments.
From repeated observations he found the smallest altitude of the new star to be 27 45', and consequently, as he assumed the latitude of Heridsvad to be 55 5 8', the declination of the star was 61 47'. He remarks that the declination was as constant as the distances from the neighboring stars, and that the instrument was not perfect enough to show the change of about a third of a minute which the precession of the equinoxes made in the decimation while the star was visible, an amount which even his later and more perfect instruments would hardly have been able to point out.
In 1577, he observed a comet. Current theory taught that both were disturbances in the atmosphere. However, Brahe's precise measurements revealed differently. He proved that the supernova never changed with regard to the surrounding stars, and that the comet orbited beyond the path of the moon, contradicting the idea that the heavens never changed.
In 1575, King Frederick II sought to keep the now-famous Brahe in Denmark by offering him his own island and financial support to study astronomy. There, Brahe built an enormous observatory, where he kept meticulous observations of the heavens. While most astronomers only focused on observing heavenly bodies at specific, unusual points in their orbits, Brahe intently tracked them in their entire visible orbit across the sky, creating the most precise observations made at the time. Some of his measurements were accurate to half an arc minute, which is especially admirable given that they were all made before the advent of the telescope.
Although Brahe's observations revealed the flaws of the current system, he did not embrace Nicolaus Copernicus' newly proposed sun-centered model. Instead, he offered a model that combined the two, setting the moon and sun in orbit around the Earth even as the other five known planets circled the sun. The model became popular among those who wanted to leave the older view behind but weren't ready to embrace the idea of the sun at the center of the solar system.
How Kepler got his start
Brahe's precise measurements laid the foundation for a new understanding of the motion of the planets. German astronomer Johannes Kepler contacted him at the end of the 16th century in an effort to obtain copies of the Danish astronomer's research. Brahe countered with a suggestion that Kepler could work as his assistant, helping him to compile his data.
However, Brahe proved more tightfisted than Kepler had anticipated and refused to share his measurements of the planets and their orbits. Instead, he suggested Kepler work on solving the Mars dilemma that plagued astronomers.
Because of its orbit, Mars appears to occasionally move backwards across the sky, causing many astronomers to suggest epicycles, tiny circles within their orbit. Even Copernicus' suggestion that the planets orbited the sun in circles could not account for the red planet's strange motion.
Kepler, using Brahe's detailed observations, realized that the planets moved around the sun not in circles but in stretched out circles known as ellipses. However, the problem took him almost a decade to solve, and Kepler didn't publish it until well after Brahe's death. Although Brahe's family intended to reap as much financial gain as possible from Brahe's observations, Kepler, by his own admission, less-than-ethically acquired them after Tycho died.
A mysterious death
Brahe died in 1601 at the age of 54. While attending a banquet, societal customs did not allow him to excuse himself before his host. Brahe had drunk excessively, but refused to leave to use the bathroom. It is thought that this caused his bladder to burst and led to his subsequent death.
However, scientists who opened Brahe's grave in 1901 to mark the 300th anniversary of his death claimed to find mercury in his remains, fueling rumors that the astronomer was poisoned. Some even accused a jealous Johannes Kepler of the crime.
Brahe's body was exhumed again in 2010. Tests on his bones and beard hairs showed that mercury concentrations in his body were not high enough to have killed him. Researchers also found that greenish stains around the nasal areas of Brahe's corpse contained traces of copper and zinc, indicating that his fake nose was made of brass and not silver or gold, as many had believed.
Tycho Brahe pronunciation
When Brahe was born, his Danish name was Tyge Otteson Brahe. However, he adopted a Latinized form, Tycho Brahe, when he was about 15 years old. There is not much consensus about how the name is pronounced in English. Some say his first name is "tee-ko"; others say "tie-ko." His last name is pronounced either "brah," "bra-hay" or "bra-hee." He is sometimes referred to only by his first name, as in Tycho Crater on the moon, the Tycho Deep Space capsule and Tycho's Supernova Remnant.
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