From Space.com:
Boeing Moves Forward With Commercial Space Capsule
By Denise Chow
SPACE.com Staff Writer
posted: 27 August 2010
01:41 pm ET
With the impending retirement of NASA's space shuttle fleet, aerospace juggernaut Boeing is hard at work developing a new capsule-based spaceship that could be ready for its first commercial spaceflight by 2015.
Boeing's new Crew Space Transportation-100 spacecraft is designed to fly astronauts to and from the International Space Station (ISS), as well as future private space stations.
Keith Reiley, Boeing's commercial crew development program manager, will be presenting updates on the Commercial Crew Transportation System at the American Institute of Aeronautics and Astronautic Space 2010 Conference and Exposition next week in Anaheim, Calif.
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As one of the leading suppliers of human space systems and services, Boeing already has a strong heritage in the industry. [Video: Boeing's New Spacecraft]
"It was an enormous advantage," Reiley told SPACE.com. "A lot of the equipment we're looking at has ISS heritage. About half of our team were designers that came from ISS and had experience with the flight hardware. The other half were space shuttle designers."
To help reach its goal, the company looked to existing facilities, launchers and proven processes to ensure safety, lower development costs and reduce overall risk.
Boeing's CST-100 spacecraft is approximately 15 feet (4.5 meters) wide and can carry up to seven people. The cone-shaped capsule will look similar to NASA's Apollo and Orion spacecraft.
Boeing settled on the cone-shaped design because it was thought to be the safest and most inexpensive of the vehicle concepts that were considered, Reiley said.
Pushy launch escape system
The spacecraft is being designed for compatibility with a variety of rockets, including United Launch Alliance's Atlas and Delta boosters and SpaceX's Falcon rockets. This will give Boeing the flexibility to select an appropriate rocket later in the development process.
The spacecraft will also be equipped with a unique pusher abort system in case the crew encounters an emergency during launch.
"This is the first time anyone has proposed or succeeded with a pusher design," Reiley said. "The pusher appears, to us, to be simpler, less expensive and just as safe."
If necessary, the launch abort system would fire pressurized propellant for three seconds to quickly push the vehicle away from the rocket. A parachute would then be deployed to assist with the landing.
One of the advantages of the pusher design is that in the event of a smooth launch, the same propellant can also be used on orbit, either in guiding the CST-100 to dock with a space station, or to boost stations themselves, whose orbits slowly decay over time.
"You get the ability to use the propellant to re-boost our customer stations or simply for orbital maneuvering to get there," Reiley said. "In order to catch up with the station you're trying to rendezvous with, you have to boost yourself up to the station's orbit, and all that takes a certain amount of fuel."
For Boeing, one of their main challenges in expanding their branch of commercial spaceflight is in designing a relatively inexpensive option.
The company has set a design requirement that the CST-100 be reusable up to 10 times. The exact number of times the capsule is reused, however, will depend upon inspection after touchdown.
The CST-100 is part of the company's $18 million award from NASA under the Commercial Crew Development (CCDev) Space Act Agreement. The award aims to advance the concepts and technology required to build a commercial crew space transportation system.
Boeing's capsule design is one of several efforts by different U.S. companies to develop the first private spaceship capable of flying humans to space. The push fits in with President Barack Obama's new plan for NASA, which calls for commercial spacecraft to take over the role vacated by the space shuttles of transporting astronauts to the space station.
Earth--Day and Night Regions
Monday, August 30, 2010
Saturday, August 21, 2010
Philosopher of the Day: Nicholas Copernicus
From Cloud of Witnesses and Stanford Encyclopedia of Philosophy:
Nicolaus Copernicus
First published Tue Nov 30, 2004; substantive revision Mon Aug 16, 2010
Nicolaus Copernicus (1473–1543) was a mathematician and astronomer who proposed that the sun was stationary in the center of the universe and the earth revolved around it. Disturbed by the failure of Ptolemy's geocentric model of the universe to follow Aristotle's requirement for the uniform circular motion of all celestial bodies and determined to eliminate Ptolemy's equant, an imaginary point around which the bodies seemed to follow that requirement, Copernicus decided that he could achieve his goal only through a heliocentric model. He thereby created a concept of a universe in which the distances of the planets from the sun bore a direct relationship to the size of their orbits. At the time Copernicus's heliocentric idea was very controversial; nevertheless, it was the start of a change in the way the world was viewed, and Copernicus came to be seen as the initiator of the Scientific Revolution.
•1. Life and Works
•2. Astronomical Ideas and Writings
◦2.1 Pre-Copernican Astronomy
◦2.2 The Commentariolus
◦2.3 On the Revolutions
◦2.4 Rheticus and the Narratio prima
◦2.5 Printing On the Revolutions and Osiander's Preface
◦2.6 Sixteenth Century Reactions to On the Revolutions
•Bibliography
•Other Internet Resources
•Related Entries
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1. Life and Works
Nicolaus Copernicus was born on 19 February 1473, the youngest of four children of Nicolaus Copernicus, Sr., a well-to-do merchant who had moved to Torun from Cracow, and Barbara Watzenrode, the daughter of a leading merchant family in Torun. The city, on the Vistula River, had been an important inland port in the Hanseatic League. However, fighting between the Order of the Teutonic Knights and the Prussian Union in alliance with the Kingdom of Poland ended in 1466, and West Prussia, which included Torun, was ceded to Poland, and Torun was declared a free city of the Polish kingdom. Thus the child of a German family was a subject of the Polish crown.
The father died in 1483, and the children's maternal uncle, Lucas Watzenrode (1447–1512), took them under his protection. Watzenrode was a very successful cleric — he was to become bishop of Warmia (Ermland in German) in 1489 — and he both facilitated his nephew's advancement in the church and directed his education. In 1491 Copernicus enrolled in the University of Cracow. There is no record of his having obtained a degree, which was not unusual at the time as he did not need a bachelor's degree for his ecclesiastical career or even to study for a higher degree. But the University of Cracow offered courses in mathematics, astronomy, and astrology (see Goddu 25–33 on all the university offerings), and Copernicus's interest was sparked, which is attested to by his acquisition of books in these subjects while at Cracow.[1]
In 1495 Watzenrode arranged Copernicus's election as canon of the chapter of Frombork (Frauenberg in German) of the Cathedral Chapter of Warmia, an administrative position just below that of bishop. He assumed the post two years later, and his financial situation was secure for life. In the meantime, following in his uncle's footsteps, Copernicus went to the University of Bologna in 1496 to study canon law (see Goddu part 2 on what Copernicus may have encountered in Italy). While at Bologna he lived with the astronomy professor Domenico Maria Novara and made his first astronomical observations. In addition, as Rosen (1971, 323) noted, “In establishing close contact with Novara, Copernicus met, perhaps for the first time in his life, a mind that dared to challenge the authority of [Ptolemy] the most eminent ancient writer in his chosen fields of study.” Copernicus also gave a lecture on mathematics in Rome, which may have focused on astronomy.
Copernicus's studies at Bologna provided an advantage he did not have at Cracow — a teacher of Greek. Humanism began to infiltrate the Italian universities in the fifteenth century. As Grendler (510) remarked, “By the last quarter of the century, practically all universities had one or several humanists, many of them major scholars.” Antonio Cortesi Urceo, called Codro, became professor at Bologna in 1482 and added Greek several years later. Copernicus may have studied with him, for Copernicus translated into Latin the letters of the seventh-century Byzantine author Theophylactus Simocatta (MW 27–71) from the 1499 edition of a collection of Greek letters produced by the Venetian humanist printer Aldus Manutius. Aldus had dedicated his edition to Urceo. Copernicus had his translation printed in 1509, his only publication prior to the On the Revolutions (De revolutionibus). It is important to note that Copernicus's acquisition of a good reading knowledge of Greek was critical for his studies in astronomy because major works by Greek astronomers, including Ptolemy, had not yet been translated into Latin, the language of the universities at the time.
Copernicus left Bologna for Frombork in 1501 without having obtained his degree. The chapter then approved another leave of absence for Copernicus to study medicine at the University of Padua. The medical curriculum did not just include medicine, anatomy, and the like when Copernicus studied it. Siraisi (1990, 16) noted that “the reception in twefth-century western Europe of Greek and Islamic technical astronomy and astrology fostered the development of medical astrology…the actual practice of medical astrology was greatest in the West between the fourteenth and the sixteenth centuries.” Astrology was taught in the medical schools of Italy. “The importance attached to the study of the stars in medieval medical education derived from a general and widely held belief that the heavenly bodies play an intermediary role in the creation of things here below and continue to influence them throughout their existence. The actual uses of astrology in medical diagnosis and treatment by learned physicians were many and various. ‘Astrological medicine’ is a vague and unsatisfactory term that can embrace any or all of the following: first, to pay attention to the supposed effect of astrological birth signs or signs at conception on the constitution and character of one's patients; second, to vary treatment according to various celestial conditions…third, to connect the doctrine of critical days in illness with astrological features, usually phases of the moon; and fourth, to predict or explain epidemics with reference to planetary conjunctions, the appearance of comets, or weather conditions” (Siraisi, 1981, 141–42). It is true that astrology required that medical students acquire some grounding in astronomy; nevertheless, it is likely that Copernicus studied astrology while at the University of Padua.[2]
Copernicus did not receive his medical degree from Padua; the degree would have taken three years, and Copernicus had only been granted a two-year leave of absence by his chapter. Instead he matriculated in the University of Ferrara, from which he obtained a doctorate in canon law. But he did not return to his chapter in Frombork; rather he went to live with his uncle in the episcopal palace in Lidzbark-Warminski (Heilsberg in German). Although he made some astronomical observations, he was immersed in church politics, and after his elderly uncle became ill in 1507, Copernicus was his attending physician. Rosen (1971, 334–35) reasonably conjectured that the bishop may have hoped that his nephew would be his successor, but Copernicus left his uncle because his duties in Lidzbark-Warminski interfered with his continuing pursuit of his studies in astronomy. He took up residence in his chapter of Frombork in 1510 and stayed there the rest of his life.
Not that leaving his uncle and moving to Frombork exempted Copernicus from continued involvement in administrative and political duties. He was responsible for the administration of various holdings, which involved heading the provisioning fund, adjudicating disputes, attending meetings, and keeping accounts and records. In response to the problem he found with the local currency, he drafted an essay on coinage (MW 176–215) in which he deplored the debasement of the currency and made recommendations for reform. His manuscripts were consulted by the leaders of both Prussia and Poland in their attempts to stabilize the currency. He was a leader for West Prussia in the war against the Teutonic Knights, which lasted from 1520–1525. He was physician for the bishop (his uncle had died in 1512) and members of the chapter, and he was consulting physician for notables in East and West Prussia.
Nevertheless, Copernicus began to work on astronomy on his own. Sometime between 1510 and 1514 he wrote an essay that has come to be known as the Commentariolus (MW 75–126) that introduced his new cosmological idea, the heliocentric universe, and he sent copies to various astronomers. He continued making astronomical observations whenever he could, hampered by the poor position for observations in Frombork and his many pressing responsibilities as canon. Nevertheless, he kept working on his manuscript of On the Revolutions. He also wrote what is known as Letter against Werner (MW 145–65) in 1524, a critique of Johann Werner's “Letter concerning the Motion of the Eighth Sphere” (De motu octavae sphaerae tractatus primus). Copernicus claimed that Werner erred in his calculation of time and his belief that before Ptolemy the movement of the fixed stars was uniform, but Copernicus's letter did not refer to his cosmological ideas.
In 1539 a young mathematician named Georg Joachim Rheticus (1514–1574) from the University of Wittenberg came to study with Copernicus. Rheticus brought Copernicus books in mathematics, in part to show Copernicus the quality of printing that was available in the German-speaking cities. He published an introduction to Copernicus's ideas, the Narratio prima (First Report). Most importantly, he convinced Copernicus to publish On the Revolutions. Rheticus oversaw most of the printing of the book, and on 24 May 1543 Copernicus held a copy of the finished work on his deathbed.
2. Astronomical Ideas and Writings
2.1 Pre-Copernican Astronomy
Classical astronomy followed principles established by Aristotle. Aristotle accepted the idea that there were four physical elements — earth, water, air, and fire. He put the earth in the center of the universe and contended that these elements were below the moon, which was the closest celestial body. There were seven planets, or wandering stars, because they had a course through the zodiac in addition to traveling around the earth: the moon, Mercury, Venus, the sun, Mars, Jupiter. Beyond that were the fixed stars. The physical elements, according to Aristotle moved vertically, depending on their ‘heaviness’ or ‘gravity’; the celestial bodies were not physical but a ‘fifth element’ or ‘quintessence’ whose nature was to move in perfect circles around the earth, making a daily rotation. Aristotle envisioned the earth as the true center of all the circles or ‘orbs’ carrying the heavenly bodies around it and all motion as ‘uniform,’ that is, unchanging.
But observers realized that the heavenly bodies did not move as Aristotle postulated. The earth was not the true center of the orbits and the motion was not uniform. The most obvious problem was that the outer planets seemed to stop, move backwards in ‘retrograde’ motion for a while, and then continue forwards. By the second century, when Ptolemy compiled his Almagest (this common name of Ptolemy's Syntaxis was derived from its Arabic title), astronomers had developed the concept that the orbit moves in ‘epicycles’ around a ‘deferrent,’ that is, they move like a flat heliacal coil around a circle around the earth. The earth was also off-center, on an ‘eccentric,’ as the heavenly bodies moved around a central point. Ptolemy added a point on a straight line opposite the eccentric, which is called the ‘equalizing point’ or the ‘equant,’ and around this point the heavenly bodies moved uniformly. Moreover, unlike the Aristotelian model, Ptolemy's Almagest did not describe a unified universe. The ancient astronomers who followed Ptolemy, however, were not concerned if his system did not describe the ‘true’ motions of the heavenly bodies; their concern was to ‘save the phenomena,’ that is, give a close approximation of where the heavenly bodies would be at a given point in time. And in an age without professional astronomers, let alone the telescope, Ptolemy did a good job plotting the courses of the heavenly bodies.
Not all Greek astronomical ideas followed this geocentric system. Pythagoreans suggested that the earth moved around a central fire (not the sun). Archimedes wrote that Aristarchus of Samos actually proposed that the earth rotated daily and revolved around the sun.[3]
During the European Middle Ages, the Islamic world was the center of astronomical thought and activity. During the ninth century several aspects of Ptolemy's solar theory were recalculated. Ibn al-Haytham in the tenth-eleventh century wrote a scathing critique of Ptolemy's work: “Ptolemy assumed an arrangement that cannot exist, and the fact that this arrangement produces in his imagination the motions that belong to the planets does not free him from the error he committed in his assumed arrangement, for the existing motions of the planets cannot be the result of an arrangement that is impossible to exist” (quoted in Rosen 1984, 174). Swerdlow and Neugebauer (46–48) stressed that the thirteenth-century Maragha school was also important in finding errors and correcting Ptolemy: “The method of the Maragha planetary models was to break up the equant motion in Ptolemy's models into two or more components of uniform circular motion, physically the uniform rotation of spheres, that together control the direction and distance of the center of the epicycle, so that it comes to lie in nearly the same position it would have in Ptolemy's model, and always moves uniformly with respect to the equant.” They found that Copernicus used devices that had been developed by the Maragha astronomers Nasir al-Din Tusi (1201-1274), Muayyad al-Din al-Urdi (d. 1266), Qutb al-Din al-Shirazi (1236-1311), and Ibn al-Shatir (1304–1375).[4] In addition, Ragep, 2005, has shown that a theory for the inner planets presented by Regiomontanus that enabled Copernicus to convert the planets to eccentric models had been developed by the fifteenth-century, Samarqand-trained astronomer Ali Qushji (1403–1474). The problem is, as Goddu (476–86) has pointed out, we have no proof of their transmission from east to west. Nevertheless, it is highly unlikely that so many similar techniques were invented independently in the west.
Renaissance humanism did not necessarily promote natural philosophy, but its emphasis on mastery of classical languages and texts had the side effect of promoting the sciences. Georg Peurbach (1423–1461) and (Johannes Müller) Regiomontanus (1436–1476) studied Greek for the purpose of producing an outline of Ptolemaic astronomy. By the time Regiomontanus finished the work in 1463, it was an important commentary on the Almagest as well, pointing out, for example, that Ptolemy's lunar theory did not accord with observations. He noted that Ptolemy showed the moon to be at various times twice as far from the earth as at other times, which should make the moon appear twice as big. At the time, moreover, there was active debate over Ptolemy's deviations from Aristotle's requirement of uniform circular motion.
2.2 The Commentariolus
It is impossible to date when Copernicus first began to espouse the heliocentric theory. Had he done so during his lecture in Rome, such a radical theory would have occasioned comment, but there was none, so it is likely that he adopted this theory after 1500. Further, Corvinus, who helped him print his Latin translation in 1508–09, expressed admiration for his knowledge of astronomy, so that Copernicus's concept may have still been traditional at this point. His first heliocentric writing was his Commentariolus. It was a small manuscript that was circulated but never printed. We do not know when he wrote this, but a professor in Cracow cataloged his books in 1514 and made reference to a “manuscript of six leaves expounding the theory of an author who asserts that the earth moves while the sun stands still” (Rosen, 1971, 343; MW 75). Thus, Copernicus probably adopted the heliocentric theory sometime between 1508 and 1514. Rosen (1971, 345) suggested that Copernicus's “interest in determining planetary positions in 1512–1514 may reasonably be linked with his decisions to leave his uncle's episcopal palace in 1510 and to build his own outdoor observatory in 1513.” In other words, it was the result of a period of intense concentration on cosmology that was facilitated by his leaving his uncle and the attendant focus on church politics and medicine.
It is impossible to know exactly why Copernicus began to espouse the heliocentric cosmology. Despite his importance in the history of philosophy, there is a paucity of primary sources on Copernicus. His only astronomical writings were the Commentariolus, the Letter against Werner, and On the Revolutions; he published his translation of Theophylactus's letters and wrote the various versions of his treatise on coinage; other writings relate to diocesan business, as do most of the few letters that survive. Sadly, the biography by Rheticus, which should have provided scholars with an enormous amount of information, has been lost. Therefore, many of the answers to the most interesting questions about Copernicus's ideas and works have been the result of conjecture and inference, and we can only guess why Copernicus adopted the heliocentric system.
Most scholars believe that the reason Copernicus rejected Ptolemaic cosmology was because of Ptolemy's equant.[5] They assume this because of what Copernicus wrote in the Commentariolus:
Yet the widespread [planetary theories], advanced by Ptolemy and most other [astronomers], although consistent with the numerical [data], seemed likewise to present no small difficulty. For these theories were not adequate unless they also conceived certain equalizing circles, which made the planet appear to move at all times with uniform velocity neither on its deferent sphere nor about its own [epicycle's] center…Therefore, having become aware of these [defects], I often considered whether there could perhaps be found a more reasonable arrangement of circles, from which every apparent irregularity would be derived while everything in itself would move uniformly, as is required by the rule of perfect motion. (MW 81).
Goddu (381–84) has plausibly maintained that while the initial motivation for Copernicus was dissatisfaction with the equant, that dissatisfaction may have impelled him to observe other violations of uniform circular motion, and those observations, not the rejection of the equant by itself, led to the heliocentric theory. Blumenberg (254) has pointed out that the mobility of the earth may have been reinforced by the similarity of its spherical shape to those of the heavenly bodies.
As the rejection of the equant suggests a return to the Aristotelian demand for true uniform circular motion of the heavenly bodies, it is unlikely that Copernicus adopted the heliocentric model because philosophies popular among Renaissance humanists like Neoplatonism and Hermetism compelled him in that direction.[6] Nor should we attribute Copernicus's desire for uniform circular motions to an aesthetic need, for this idea was philosophical not aesthetic, and Copernicus's replacing the equant with epicyclets made his system more complex than Ptolemy's. Most importantly, we should bear in mind what Swerdlow and Neugebauer (59) asserted:
Copernicus arrived at the heliocentric theory by a careful analysis of planetary models — and as far as is known, he was the only person of his age to do so — and if he chose to adopt it, he did so on the basis of an equally careful analysis.
In the Commentariolus Copernicus listed assumptions that he believed solved the problems of ancient astronomy. He stated that the earth is only the center of gravity and center of the moon's orbit; that all the spheres encircle the sun, which is close to the center of the universe; that the universe is much larger than previously assumed, and the earth's distance to the sun is a small fraction of the size of the universe; that the apparent motion of the heavens and the sun is created by the motion of the earth; and that the apparent retrograde motion of the planets is created by the earth's motion. Although the Copernican model maintained epicycles moving along the deferrent, which explained retrograde motion in the Ptolemaic model, Copernicus correctly explained that the retrograde motion of the planets was only apparent not real, and its appearance was due to the fact that the observers were not at rest in the center. The work dealt very briefly with the order of the planets (Mercury, Venus, earth, Mars, Jupiter, and Saturn, the only planets that could be observed with the naked eye), the triple motion of the earth (the daily rotation, the annual revolution of its center, and the annual revolution of its inclination) that causes the sun to seem to be in motion, the motions of the equinoxes, the revolution of the moon around the earth, and the revolution of the five planets around the sun.
2.3 On the Revolutions
The Commentariolus was only intended as an introduction to Copernicus's ideas, and he wrote “the mathematical demonstrations intended for my larger work should be omitted for brevity's sake…” (MW 82). In a sense it was an announcement of the greater work that Copernicus had begun. The Commentariolus was never published during Copernicus's lifetime, but he sent manuscript copies to various astronomers and philosophers. He received some discouragement because the heliocentric system seemed to disagree with the Bible, but mostly he was encouraged. Although Copernicus's involvement with official attempts to reform the calendar was limited to a no longer extant letter, that endeavor made a new, serious astronomical theory welcome. Fear of the reaction of ecclesiastical authorities was probably the least of the reasons why he delayed publishing his book.[7] The most important reasons for the delay was that the larger work required both astronomical observations and intricate mathematical proofs. His administrative duties certainly interfered with both the research and the writing. He was unable to make the regular observations that he needed and Frombork, which was often fogged in, was not a good place for those observations. Moreover, as Gingerich (1993, 37) pointed out,
[Copernicus] was far from the major international centers of printing that could profitably handle a book as large and technical as De revolutionibus. On the other [hand], his manuscript was still full of numerical inconsistencies, and he knew very well that he had not taken complete advantage of the opportunities that the heliocentric viewpoint offered…Furthermore, Copernicus was far from academic centers, thereby lacking the stimulation of technically trained colleagues with whom he could discuss his work.
The manuscript of On the Revolutions was basically complete when Rheticus came to visit him in 1539. The work comprised six books. The first book, the best known, discussed what came to be known as the Copernican theory and what is Copernicus's most important contribution to astronomy, the heliocentric universe (although in Copernicus's model, the sun is not truly in the center). Book 1 set out the order of the heavenly bodies about the sun: “[The sphere of the fixed stars] is followed by the first of the planets, Saturn, which completes its circuit in 30 years. After Saturn, Jupiter accomplishes its revolution in 12 years. The Mars revolves in 2 years. The annual revolution takes the series' fourth place, which contains the earth…together with the lunar sphere as an epicycle. In the fifth place Venus returns in 9 months. Lastly, the sixth place is held by Mercury, which revolves in a period of 80 days” (Revolutions, 21–22). This established a relationship between the order of the planets and their periods, and it made a unified system. This may be the most important argument in favor of the heliocentric model as Copernicus described it.[8] It was far superior to Ptolemy's model, which had the planets revolving around the earth so that the sun, Mercury, and Venus all had the same annual revolution. In book 1 Copernicus also insisted that the movements of all bodies must be circular and uniform, and noted that the reason they may appear nonuniform to us is “either that their circles have poles different [from the earth's] or that the earth is not at the center of the circles on which they revolve” (Revolutions, 11). Particularly notable for Copernicus was that in Ptolemy's model the sun, the moon, and the five planets seemed ironically to have different motions from the other heavenly bodies and it made more sense for the small earth to move than the immense heavens. But the fact that Copernicus turned the earth into a planet did not cause him to reject Aristotelian physics, for he maintained that “land and water together press upon a single center of gravity; that the earth has no other center of magnitude; that, since earth is heavier, its gaps are filled with water…” (Revolutions, 10). As Aristotle had asserted, the earth was the center toward which the physical elements gravitate. This was a problem for Copernicus's model, because if the earth was no longer the center, why should elements gravitate toward it?
The second book of On the Revolutions elaborated the concepts in the first book; book 3 dealt with the precession of the equinoxes and solar theory; book 4 dealt with the moon's motions; book 5 dealt with the planetary longitude and book 6 with latitude.[9] Copernicus depended very much on Ptolemy's observations, and there was little new in his mathematics. He was most successful in his work on planetary longitude, which, as Swerdlow and Neugebauer (77) commented, was “Copernicus's most admirable, and most demanding, accomplishment…It was above all the decision to derive new elements for the planets that delayed for nearly half a lifetime Copernicus's continuation of his work — nearly twenty years devoted to observation and then several more to the most tedious kind of computation — and the result was recognized by his contemporaries as the equal of Ptolemy's accomplishment, which was surely the highest praise for an astronomer.” Surprisingly, given that the elimination of the equant was so important in the Commentariolus, Copernicus did not mention it in book 1, but he sought to replace it with an epicyclet throughout On the Revolutions. Nevertheless, he did write in book 5 when describing the motion of Mercury:
…the ancients allowed the epicycle to move uniformly only around the equant's center. This procedure was in gross conflict with the true center [of the epicycle's motion], its relative [distances], and the prior centers of both [other circles]…However, in order that this last planet too may be rescued from the affronts and pretenses of its detractors, and that its uniform motion, no less than that of the other aforementioned planets, may be revealed in relation to the earth's motion, I shall attribute to it too, [as the circle mounted] on its eccentric, an eccentric instead of the epicycle accepted in antiquity (Revolutions, 278–79).
2.4 Rheticus and the Narratio prima
Although Copernicus received encouragement to publish his book from his close friend, the bishop of Chelmo Tiedemann Giese (1480–1550), and from the cardinal of Capua Nicholas Schönberg (1472–1537), it was the arrival of Georg Joachim Rheticus in Frombork that solved his needs for a supportive and stimulating colleague in mathematics and astronomy and for access to an appropriate printer. Rheticus was a professor of mathematics at the University of Wittenberg, a major center for the student of mathematics as well as for Lutheran theology. In 1538 Rheticus took a leave of absence to visit several famous scholars in the fields of astronomy and mathematics. It is not known how Rheticus learned about Copernicus's theory; he may have been convinced to visit Copernicus by one of the earlier scholars he had visited, Johann Schöner, though, as Swerdlow and Neugebauer (16) noted, by “the early 1530's knowledge of Copernicus's new theory was circulating in Europe, even reaching the high and learned circles of the Vatican.” Rheticus brought with him some mathematical and astronomical volumes, which both provided Copernicus with some important material and showed him the quality of the mathematical printing available in the German centers of publishing.[10] Rheticus's present of the 1533 edition of Regiomontanus's On all Kinds of Triangles (De triangulis omnimodis), for example, convinced Copernicus to revise his section on trigonometry. But Rheticus was particularly interested in showing Copernicus the work of the Nuremberg publisher Johann Petreius as a possible publisher of Copernicus's volume. Swerdlow and Neugebauer (25) plausibly suggested that “Petreius was offering to publish Copernicus's work, if not advertising by this notice that he was already committed to do so.” Rheticus wrote the Narratio prima in 1540, an introduction to the theories of Copernicus, which was published and circulated. This further encouraged Copernicus to publish his Revolutions, which he had been working on since he published the Commentariolus.
The Narratio prima was written in 1539 and took the form of a letter to Johann Schöner announcing Copernicus's findings and describing the contents of the Revolutions. He dealt with such topics as the motions of the fixed stars, the tropical year, the obliquity of the ecliptic, the problems resulting from the motion of the sun, the motions of the earth and the other planets, librations, longitude in the other five planets, and the apparent deviation of the planets from the ecliptic. He asserted that the heliocentric universe should have been adopted because it better accounted for such phenomena as the precession of the equinoxes and the change in the obliquity of the ecliptic; it resulted in a diminution of the eccentricity of the sun; the sun was the center of the deferents of the planets; it allowed the circles in the universe to revolve uniformly and regularly; it satisfied appearances more readily with fewer explanations necessary; it united all the spheres into one system. Rheticus added astrological predictions and number mysticism, which were absent from Copernicus's work.
The Narratio prima was printed in 1540 in Gdansk (then Danzig); thus, it was the first printed description of the Copernican thesis. Rheticus sent a copy to Achilles Pirmin Gasser of Feldkirch, his hometown in modern-day Austria, and Gasser wrote a foreword that was published with a second edition that was produced in 1541 in Basel. It was published again in 1596 as an appendix to the first edition of Johannes Kepler's Mysterium cosmographicum (Secret of the Universe), the first completely Copernican work by an adherent since the publications by Copernicus and Rheticus.
2.5 Printing On the Revolutions and Osiander's Preface
The publication of Rheticus's Narratio prima did not create a big stir against the heliocentric thesis, and so Copernicus decided to publish On the Revolutions. He added a dedication to Pope Paul III (r. 1534–1549), probably for political reasons, in which he expressed his hesitancy about publishing the work and the reasons he finally decided to publish it. He gave credit to Schönberg and Giese for encouraging him to publish and omitted mention of Rheticus, but it would have been insulting to the pope during the tense period of the Reformation to give credit to a Protestant minister.[11] He dismissed critics who might have claimed that it was against the Bible by giving the example of the fourth-century Christian apologist Lactantius, who had rejected the spherical shape of the earth, and by asserting, “Astronomy is written for astronomers” (Revolutions, 5). In other words, theologians should not meddle with it. He pointed to the difficulty of calendar reform because the motions of the heavenly bodies were inadequately known. And he called attention to the fact that “if the motions of the other planets are correlated with the orbiting of the earth, and are computed for the revolution of each planet, not only do their phenomena follow therefrom but also the order and size of all the planets and spheres, and heaven itself is so linked together that in no portion of it can anything be shifted without disrupting the remaining parts and the universe as a whole” (Revolutions, 5).
Rheticus returned to Wittenberg in 1541 and the following year received another leave of absence, at which time he took the manuscript of the Revolutions to Petreius for publishing in Nuremberg. Rheticus oversaw the printing of most of the text. However, Rheticus was forced to leave Nuremberg later that year because he was appointed professor of mathematics at the University of Leipzig. He left the rest of the management of printing the Revolutions to Andrew Osiander (1498–1552), a Lutheran minister who was also interested in mathematics and astronomy. Though he saw the project through, Osiander appended an anonymous preface to the work. In it he claimed that Copernicus was offering a hypothesis, not a true account of the working of the heavens: “Since he [the astronomer] cannot in any way attain to the true causes, he will adopt whatever suppositions enable the motions to be computed correctly from the principles of geometry for the future as well as for the past …these hypotheses need not be true nor even probable” (Revolutions, xvi). This clearly contradicted the body of the work. Both Rheticus and Giese protested, and Rheticus crossed it out in his copy.
2.6 Sixteenth Century Reactions to On the Revolutions
Copernicus's fame and book made its way across Europe over the next fifty years, and a second edition was brought out in 1566.[12] As Gingerich's census of the extant copies showed, the book was read and commented on by astronomers. Gingerich (2004, 55) noted “the majority of sixteenth-century astronomers thought eliminating the equant was Copernicus' big achievement.”
While Martin Luther may have made negative comments about Copernicus because the idea of the heliocentric universe seemed to contradict the Bible,[13] Philip Melanchthon (1497–1560), who presided over the curriculum at the University of Wittenberg, eventually accepted the importance of teaching Copernicus's ideas, perhaps because Osiander's preface made the work more palatable. His son-in-law Caspar Peucer (1525-1602) taught astronomy there and began teaching Copernicus's work. As a result, the University of Wittenberg became a center where Copernicus's work was studied. But Rheticus was the only Wittenberg scholar who accepted the heliocentric idea. Robert Westman (1975a, 166–67) suggested that there was a ‘Wittenberg Interpretation’: astronomers appreciated and adopted some of Copernicus's mathematical models but rejected his cosmology, and some were pleased with his replacement of the equant by epicyclets. One of these was Erasmus Reinhold (1511–1553), a leading astronomer at Wittenberg who became dean and rector. He produced a new set of planetary tables from Copernicus's work, the Prutenic Tables. Although, as Gingerich (1993, 232) pointed out, “there was relatively little to distinguish between the accuracy of the Alfonsine Tables and the Prutenic Tables,” the latter were more widely adopted; Gingerich plausibly suggested that the fact that the Prutenic Tables more accurately predicted a conjunction between Jupiter and Saturn in 1563 made the difference. Reinhold did not accept the heliocentric theory, but he admired the elimination of the equant. The Prutenic Tables excited interest in Copernicus's work.
Tycho Brahe (1546–1601) was the greatest astronomical observer before the invention of the telescope. He called Copernicus a ‘second Ptolemy’ (quoted in Westman 1975, 307) and appreciated both the elimination of the equant and the creation of a planetary system. But Tycho could not adopt the Copernican system, partly for the religious reason that it went against what the Bible seemed to preach. He, therefore, adopted a compromise, the ‘geoheliostatic’ system in which the two inner planets revolved around the sun and that system along with the rest of the planets revolved around the earth.
Among Catholics, Christoph Clavius (1537–1612) was the leading astronomer in the sixteenth century. A Jesuit himself, he incorporated astronomy into the Jesuit curriculum and was the principal scholar behind the creation of the Gregorian calendar. Like the Wittenberg astronomers, Clavius adopted Copernican mathematical models when he felt them superior, but he believed that Ptolemy's cosmology — both his ordering of the planets and his use of the equant — was correct.
Pope Clement VII (r. 1523–1534) had reacted favorably to a talk about Copernicus's theories, rewarding the speaker with a rare manuscript. There is no indication of how Pope Paul III, to whom On the Revolutions was dedicated reacted; however, a trusted advisor, Bartolomeo Spina of Pisa (1474–1546) intended to condemn it but fell ill and died before his plan was carried out (see Rosen, 1975). Thus, in 1600 there was no official Catholic position on the Copernican system, and it was certainly not a heresy. When Giordano Bruno (1548–1600) was burned at the stake as a heretic, it had nothing to do with his writings in support of Copernican cosmology, and this is clearly shown in Finocchiaro's reconstruction of the accusations against Bruno (see also Blumenberg's part 3, chapter 5, titled “Not a Martyr for Copernicanism: Giordano Bruno”).
Michael Maestlin (1550–1631) of the University of Tübingen was the earliest astronomer after Rheticus to adopt Copernicus's heliocentricism. Although he wrote a popular textbook that was geocentric, he taught his students that the heliocentric system was superior. He also rejected Osiander's preface. Maestlin's pupil Johannes Kepler wrote the first book since the publication of On the Revolutions that was openly heliocentric in its orientation, the Mysterium cosmographicum (Secret of the Universe). And, of course, Kepler eventually built on Copernicus's work to create a much more accurate description of the solar system.
Bibliography
A. Complete Works of Copernicus
In 1972 the Polish Academy of Sciences under the direction of J. Dobrzycki published critical editions of the Complete Works of Copernicus in six languages: Latin, English, French, German, Polish, and Russian. The first volume was a facsimile edition. The annotations in the English translations are more comprehensive than the others. The English edition was reissued as follows:
Minor Works, 1992, trans. E. Rosen, Baltimore: The Johns Hopkins University Press (originally published as volume 3 of Nicholas Copernicus: Complete Works, Warsaw: Polish Scientific Publishers, 1985). Referred to herein as MW.
On the Revolutions, 1992, trans. E. Rosen, Baltimore: The Johns Hopkins University Press (originally published as volume 2 of Nicholas Copernicus: Complete Works, Warsaw: Polish Scientific Publishers, 1978). Referred to herein as Revolutions.
B. Other Translations of Copernicus's Works
On the Revolutions of the Heavenly Spheres, 1955, trans. C.G. Wallis, vol. 16 of Great Books of the Western World, Chicago: Encyclopedia Britannica; 1995, reprint, Amherst: Prometheus Books.
On the Revolutions of the Heavenly Spheres, 1976, trans. and ed. A.M. Duncan, Newton Abbot: David & Charles.
“The Derivation and First Draft of Copernicus's Planetary Theory: A Translation of the Commentariolus with Commentary,” 1973, trans. N.M. Swerdlow, Proceedings of the American Philosophical Society, 117: 423–512.
C. Translations of Other Primary Sources
Bruno, G., 1977, The Ash Wednesday Supper, trans. E.A. Gosselin and L.S. Lerner, Hamden: Archon Books, 1995; reprint, Toronto: University of Toronto Press.
Rheticus, G.J., Narratio prima, in E. Rosen, 1971, 107–96.
D. Secondary Sources
Blumenberg, H., 1987, The Genesis of the Copernican World, trans. R.M. Wallace, Cambridge, MA: MIT Press.
Cohen, I.B., 1960, The Birth of a New Physics, Garden City: Anchor Books; rev. ed., New York: W.W. Norton, 1985.
–––, 1985, Revolutions in Science, Cambridge, MA: Harvard University Press.
Crowe, M.J., 1990, Theories of the World from Antiquity to the Copernican Revolution, New York: Dover Publications.
Finocchiaro, M.A., 2002, “Philosophy versus Religion and Science versus Religion: the Trials of Bruno and Galileo,” in H. Gatti (ed.), 51–96.
Gatti, H. (ed.), 2002, Giordano Bruno: Philosopher of the Renaissance, Aldershot: Ashgate.
Gillespie, C.C. (ed.), 1970–80, Dictionary of Scientific Biography, New York: Scribner's.
Gingerich, O., 1993, The Eye of Heaven: Ptolemy, Copernicus, Kepler, New York: American Institute of Physics.
–––, 2002, An Annotated Census of Copernicus' De revolutionibus, Leiden: Brill Academic Publishers; Nuremberg, 1543 and Basel, 1566.
–––, 2004, The Book Nobody Read: Chasing the Revolutions of Nicolaus Copernicus, New York: Walker & Company.
Goddu, A., 2010, Copernicus and the Aristotelian Tradition: Education, Reading, and Philosophy in Copernicus's Path to Heliocentrism, Leiden: Brill.
Grendler, P., 2002, The Universities of the Italian Renaissance, Baltimore: The Johns Hopkins University Press.
Hallyn, F., 1990, The Poetic Structure of the World: Copernicus and Kepler, trans. D. Leslie, New York: Zone Books.
Koestler, A., 1989, The Sleepwalkers, London: Penguin, reprint of 1959 edition.
Koyré, A., 1957, From the Closed World to the Infinite Universe, Baltimore: The Johns Hopkins University Press.
–––, 1973, The Astronomical Revolution: Copernicus, Kepler, Borelli, trans. R.E.W. Maddison, Ithaca: Cornell University Press.
Kuhn, T., 1957, The Copernican Revolution, Cambridge, MA: Harvard University Press.
Ragep, F.J., 2005, “Ali Qushji and Regiomontanus,” Journal for the History of Astronomy, 36: 359–71.
–––, 2007, “Copernicus and His Islamic Predecessors,” History of Science, 45: 65–81.
Rosen, E.,1970a, “Copernicus,” in Gillespie (ed.), 3: 401–11.
–––, 1970b, “Rheticus,” Gillespie (ed.), 11: 395–97.
–––, 1971, Three Copernican Treatises, 3d ed., New York: Octagon Books.
–––, 1975, “Was Copernicus' Revolutions Approved by the Pope?” Journal of the History of Ideas, 36: 531–42.
–––, 1984, Copernicus and the Scientific Revolution, Malabar, FL: Krieger Publishing Co.
Saliba, G., 2007, Islamic Science and the Making of the European Renaissance, Cambridge, MA: MIT Press.
Shumaker, W., 1979, The Occult Sciences in the Renaissance: A Study in Intellectual Patterns, Berkeley: University of California Press, reprint of 1972 edition.
Siraisi, N., 1981, Taddeo Alderotti and His Pupils: Two Generations of Italian Medical Learning, Princeton: Princeton University Press.
–––, 1990, Medieval and Early Renaissance Medicine: An Introduction to Knowledge and Practice, Chicago: University of Chicago Press.
Swerdlow, N., 2000, “Copernicus, Nicolaus (1473–1543),” in Encyclopedia of the Scientific Revolution, W. Applebaum (ed.), New York: Garland Publishing, 162–68.
Swerdlow, N. and O. Neugebauer, 1984, Mathematical Astronomy in Copernicus's De Revolutionibus, 2 vols., New York: Springer-Verlag.
Westman, R., 1975a, “The Melanchthon Circle, Rheticus, and the Wittenberg Interpretation of the Copernican Theory,” Isis, 66: 165–93.
–––, 1975b, “Three Responses to the Copernican Theory: Johannes Praetorius, Tycho Brahe, and Michael Maestlin,” in Westman (ed.), 1975c.
–––, (ed), 1975c, The Copernican Achievement, Berkeley: University of California Press.
–––, 1993, “Copernicus and the Prognosticators: The Bologna Period, 1496–1500,” Universitas, 5 (December): 1–5.
Yates, F., 1979, Giordano Bruno and the Hermetic Tradition, Chicago: University of Chicago Press, reprint of 1964 edition.
Nicolaus Copernicus
First published Tue Nov 30, 2004; substantive revision Mon Aug 16, 2010
Nicolaus Copernicus (1473–1543) was a mathematician and astronomer who proposed that the sun was stationary in the center of the universe and the earth revolved around it. Disturbed by the failure of Ptolemy's geocentric model of the universe to follow Aristotle's requirement for the uniform circular motion of all celestial bodies and determined to eliminate Ptolemy's equant, an imaginary point around which the bodies seemed to follow that requirement, Copernicus decided that he could achieve his goal only through a heliocentric model. He thereby created a concept of a universe in which the distances of the planets from the sun bore a direct relationship to the size of their orbits. At the time Copernicus's heliocentric idea was very controversial; nevertheless, it was the start of a change in the way the world was viewed, and Copernicus came to be seen as the initiator of the Scientific Revolution.
•1. Life and Works
•2. Astronomical Ideas and Writings
◦2.1 Pre-Copernican Astronomy
◦2.2 The Commentariolus
◦2.3 On the Revolutions
◦2.4 Rheticus and the Narratio prima
◦2.5 Printing On the Revolutions and Osiander's Preface
◦2.6 Sixteenth Century Reactions to On the Revolutions
•Bibliography
•Other Internet Resources
•Related Entries
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1. Life and Works
Nicolaus Copernicus was born on 19 February 1473, the youngest of four children of Nicolaus Copernicus, Sr., a well-to-do merchant who had moved to Torun from Cracow, and Barbara Watzenrode, the daughter of a leading merchant family in Torun. The city, on the Vistula River, had been an important inland port in the Hanseatic League. However, fighting between the Order of the Teutonic Knights and the Prussian Union in alliance with the Kingdom of Poland ended in 1466, and West Prussia, which included Torun, was ceded to Poland, and Torun was declared a free city of the Polish kingdom. Thus the child of a German family was a subject of the Polish crown.
The father died in 1483, and the children's maternal uncle, Lucas Watzenrode (1447–1512), took them under his protection. Watzenrode was a very successful cleric — he was to become bishop of Warmia (Ermland in German) in 1489 — and he both facilitated his nephew's advancement in the church and directed his education. In 1491 Copernicus enrolled in the University of Cracow. There is no record of his having obtained a degree, which was not unusual at the time as he did not need a bachelor's degree for his ecclesiastical career or even to study for a higher degree. But the University of Cracow offered courses in mathematics, astronomy, and astrology (see Goddu 25–33 on all the university offerings), and Copernicus's interest was sparked, which is attested to by his acquisition of books in these subjects while at Cracow.[1]
In 1495 Watzenrode arranged Copernicus's election as canon of the chapter of Frombork (Frauenberg in German) of the Cathedral Chapter of Warmia, an administrative position just below that of bishop. He assumed the post two years later, and his financial situation was secure for life. In the meantime, following in his uncle's footsteps, Copernicus went to the University of Bologna in 1496 to study canon law (see Goddu part 2 on what Copernicus may have encountered in Italy). While at Bologna he lived with the astronomy professor Domenico Maria Novara and made his first astronomical observations. In addition, as Rosen (1971, 323) noted, “In establishing close contact with Novara, Copernicus met, perhaps for the first time in his life, a mind that dared to challenge the authority of [Ptolemy] the most eminent ancient writer in his chosen fields of study.” Copernicus also gave a lecture on mathematics in Rome, which may have focused on astronomy.
Copernicus's studies at Bologna provided an advantage he did not have at Cracow — a teacher of Greek. Humanism began to infiltrate the Italian universities in the fifteenth century. As Grendler (510) remarked, “By the last quarter of the century, practically all universities had one or several humanists, many of them major scholars.” Antonio Cortesi Urceo, called Codro, became professor at Bologna in 1482 and added Greek several years later. Copernicus may have studied with him, for Copernicus translated into Latin the letters of the seventh-century Byzantine author Theophylactus Simocatta (MW 27–71) from the 1499 edition of a collection of Greek letters produced by the Venetian humanist printer Aldus Manutius. Aldus had dedicated his edition to Urceo. Copernicus had his translation printed in 1509, his only publication prior to the On the Revolutions (De revolutionibus). It is important to note that Copernicus's acquisition of a good reading knowledge of Greek was critical for his studies in astronomy because major works by Greek astronomers, including Ptolemy, had not yet been translated into Latin, the language of the universities at the time.
Copernicus left Bologna for Frombork in 1501 without having obtained his degree. The chapter then approved another leave of absence for Copernicus to study medicine at the University of Padua. The medical curriculum did not just include medicine, anatomy, and the like when Copernicus studied it. Siraisi (1990, 16) noted that “the reception in twefth-century western Europe of Greek and Islamic technical astronomy and astrology fostered the development of medical astrology…the actual practice of medical astrology was greatest in the West between the fourteenth and the sixteenth centuries.” Astrology was taught in the medical schools of Italy. “The importance attached to the study of the stars in medieval medical education derived from a general and widely held belief that the heavenly bodies play an intermediary role in the creation of things here below and continue to influence them throughout their existence. The actual uses of astrology in medical diagnosis and treatment by learned physicians were many and various. ‘Astrological medicine’ is a vague and unsatisfactory term that can embrace any or all of the following: first, to pay attention to the supposed effect of astrological birth signs or signs at conception on the constitution and character of one's patients; second, to vary treatment according to various celestial conditions…third, to connect the doctrine of critical days in illness with astrological features, usually phases of the moon; and fourth, to predict or explain epidemics with reference to planetary conjunctions, the appearance of comets, or weather conditions” (Siraisi, 1981, 141–42). It is true that astrology required that medical students acquire some grounding in astronomy; nevertheless, it is likely that Copernicus studied astrology while at the University of Padua.[2]
Copernicus did not receive his medical degree from Padua; the degree would have taken three years, and Copernicus had only been granted a two-year leave of absence by his chapter. Instead he matriculated in the University of Ferrara, from which he obtained a doctorate in canon law. But he did not return to his chapter in Frombork; rather he went to live with his uncle in the episcopal palace in Lidzbark-Warminski (Heilsberg in German). Although he made some astronomical observations, he was immersed in church politics, and after his elderly uncle became ill in 1507, Copernicus was his attending physician. Rosen (1971, 334–35) reasonably conjectured that the bishop may have hoped that his nephew would be his successor, but Copernicus left his uncle because his duties in Lidzbark-Warminski interfered with his continuing pursuit of his studies in astronomy. He took up residence in his chapter of Frombork in 1510 and stayed there the rest of his life.
Not that leaving his uncle and moving to Frombork exempted Copernicus from continued involvement in administrative and political duties. He was responsible for the administration of various holdings, which involved heading the provisioning fund, adjudicating disputes, attending meetings, and keeping accounts and records. In response to the problem he found with the local currency, he drafted an essay on coinage (MW 176–215) in which he deplored the debasement of the currency and made recommendations for reform. His manuscripts were consulted by the leaders of both Prussia and Poland in their attempts to stabilize the currency. He was a leader for West Prussia in the war against the Teutonic Knights, which lasted from 1520–1525. He was physician for the bishop (his uncle had died in 1512) and members of the chapter, and he was consulting physician for notables in East and West Prussia.
Nevertheless, Copernicus began to work on astronomy on his own. Sometime between 1510 and 1514 he wrote an essay that has come to be known as the Commentariolus (MW 75–126) that introduced his new cosmological idea, the heliocentric universe, and he sent copies to various astronomers. He continued making astronomical observations whenever he could, hampered by the poor position for observations in Frombork and his many pressing responsibilities as canon. Nevertheless, he kept working on his manuscript of On the Revolutions. He also wrote what is known as Letter against Werner (MW 145–65) in 1524, a critique of Johann Werner's “Letter concerning the Motion of the Eighth Sphere” (De motu octavae sphaerae tractatus primus). Copernicus claimed that Werner erred in his calculation of time and his belief that before Ptolemy the movement of the fixed stars was uniform, but Copernicus's letter did not refer to his cosmological ideas.
In 1539 a young mathematician named Georg Joachim Rheticus (1514–1574) from the University of Wittenberg came to study with Copernicus. Rheticus brought Copernicus books in mathematics, in part to show Copernicus the quality of printing that was available in the German-speaking cities. He published an introduction to Copernicus's ideas, the Narratio prima (First Report). Most importantly, he convinced Copernicus to publish On the Revolutions. Rheticus oversaw most of the printing of the book, and on 24 May 1543 Copernicus held a copy of the finished work on his deathbed.
2. Astronomical Ideas and Writings
2.1 Pre-Copernican Astronomy
Classical astronomy followed principles established by Aristotle. Aristotle accepted the idea that there were four physical elements — earth, water, air, and fire. He put the earth in the center of the universe and contended that these elements were below the moon, which was the closest celestial body. There were seven planets, or wandering stars, because they had a course through the zodiac in addition to traveling around the earth: the moon, Mercury, Venus, the sun, Mars, Jupiter. Beyond that were the fixed stars. The physical elements, according to Aristotle moved vertically, depending on their ‘heaviness’ or ‘gravity’; the celestial bodies were not physical but a ‘fifth element’ or ‘quintessence’ whose nature was to move in perfect circles around the earth, making a daily rotation. Aristotle envisioned the earth as the true center of all the circles or ‘orbs’ carrying the heavenly bodies around it and all motion as ‘uniform,’ that is, unchanging.
But observers realized that the heavenly bodies did not move as Aristotle postulated. The earth was not the true center of the orbits and the motion was not uniform. The most obvious problem was that the outer planets seemed to stop, move backwards in ‘retrograde’ motion for a while, and then continue forwards. By the second century, when Ptolemy compiled his Almagest (this common name of Ptolemy's Syntaxis was derived from its Arabic title), astronomers had developed the concept that the orbit moves in ‘epicycles’ around a ‘deferrent,’ that is, they move like a flat heliacal coil around a circle around the earth. The earth was also off-center, on an ‘eccentric,’ as the heavenly bodies moved around a central point. Ptolemy added a point on a straight line opposite the eccentric, which is called the ‘equalizing point’ or the ‘equant,’ and around this point the heavenly bodies moved uniformly. Moreover, unlike the Aristotelian model, Ptolemy's Almagest did not describe a unified universe. The ancient astronomers who followed Ptolemy, however, were not concerned if his system did not describe the ‘true’ motions of the heavenly bodies; their concern was to ‘save the phenomena,’ that is, give a close approximation of where the heavenly bodies would be at a given point in time. And in an age without professional astronomers, let alone the telescope, Ptolemy did a good job plotting the courses of the heavenly bodies.
Not all Greek astronomical ideas followed this geocentric system. Pythagoreans suggested that the earth moved around a central fire (not the sun). Archimedes wrote that Aristarchus of Samos actually proposed that the earth rotated daily and revolved around the sun.[3]
During the European Middle Ages, the Islamic world was the center of astronomical thought and activity. During the ninth century several aspects of Ptolemy's solar theory were recalculated. Ibn al-Haytham in the tenth-eleventh century wrote a scathing critique of Ptolemy's work: “Ptolemy assumed an arrangement that cannot exist, and the fact that this arrangement produces in his imagination the motions that belong to the planets does not free him from the error he committed in his assumed arrangement, for the existing motions of the planets cannot be the result of an arrangement that is impossible to exist” (quoted in Rosen 1984, 174). Swerdlow and Neugebauer (46–48) stressed that the thirteenth-century Maragha school was also important in finding errors and correcting Ptolemy: “The method of the Maragha planetary models was to break up the equant motion in Ptolemy's models into two or more components of uniform circular motion, physically the uniform rotation of spheres, that together control the direction and distance of the center of the epicycle, so that it comes to lie in nearly the same position it would have in Ptolemy's model, and always moves uniformly with respect to the equant.” They found that Copernicus used devices that had been developed by the Maragha astronomers Nasir al-Din Tusi (1201-1274), Muayyad al-Din al-Urdi (d. 1266), Qutb al-Din al-Shirazi (1236-1311), and Ibn al-Shatir (1304–1375).[4] In addition, Ragep, 2005, has shown that a theory for the inner planets presented by Regiomontanus that enabled Copernicus to convert the planets to eccentric models had been developed by the fifteenth-century, Samarqand-trained astronomer Ali Qushji (1403–1474). The problem is, as Goddu (476–86) has pointed out, we have no proof of their transmission from east to west. Nevertheless, it is highly unlikely that so many similar techniques were invented independently in the west.
Renaissance humanism did not necessarily promote natural philosophy, but its emphasis on mastery of classical languages and texts had the side effect of promoting the sciences. Georg Peurbach (1423–1461) and (Johannes Müller) Regiomontanus (1436–1476) studied Greek for the purpose of producing an outline of Ptolemaic astronomy. By the time Regiomontanus finished the work in 1463, it was an important commentary on the Almagest as well, pointing out, for example, that Ptolemy's lunar theory did not accord with observations. He noted that Ptolemy showed the moon to be at various times twice as far from the earth as at other times, which should make the moon appear twice as big. At the time, moreover, there was active debate over Ptolemy's deviations from Aristotle's requirement of uniform circular motion.
2.2 The Commentariolus
It is impossible to date when Copernicus first began to espouse the heliocentric theory. Had he done so during his lecture in Rome, such a radical theory would have occasioned comment, but there was none, so it is likely that he adopted this theory after 1500. Further, Corvinus, who helped him print his Latin translation in 1508–09, expressed admiration for his knowledge of astronomy, so that Copernicus's concept may have still been traditional at this point. His first heliocentric writing was his Commentariolus. It was a small manuscript that was circulated but never printed. We do not know when he wrote this, but a professor in Cracow cataloged his books in 1514 and made reference to a “manuscript of six leaves expounding the theory of an author who asserts that the earth moves while the sun stands still” (Rosen, 1971, 343; MW 75). Thus, Copernicus probably adopted the heliocentric theory sometime between 1508 and 1514. Rosen (1971, 345) suggested that Copernicus's “interest in determining planetary positions in 1512–1514 may reasonably be linked with his decisions to leave his uncle's episcopal palace in 1510 and to build his own outdoor observatory in 1513.” In other words, it was the result of a period of intense concentration on cosmology that was facilitated by his leaving his uncle and the attendant focus on church politics and medicine.
It is impossible to know exactly why Copernicus began to espouse the heliocentric cosmology. Despite his importance in the history of philosophy, there is a paucity of primary sources on Copernicus. His only astronomical writings were the Commentariolus, the Letter against Werner, and On the Revolutions; he published his translation of Theophylactus's letters and wrote the various versions of his treatise on coinage; other writings relate to diocesan business, as do most of the few letters that survive. Sadly, the biography by Rheticus, which should have provided scholars with an enormous amount of information, has been lost. Therefore, many of the answers to the most interesting questions about Copernicus's ideas and works have been the result of conjecture and inference, and we can only guess why Copernicus adopted the heliocentric system.
Most scholars believe that the reason Copernicus rejected Ptolemaic cosmology was because of Ptolemy's equant.[5] They assume this because of what Copernicus wrote in the Commentariolus:
Yet the widespread [planetary theories], advanced by Ptolemy and most other [astronomers], although consistent with the numerical [data], seemed likewise to present no small difficulty. For these theories were not adequate unless they also conceived certain equalizing circles, which made the planet appear to move at all times with uniform velocity neither on its deferent sphere nor about its own [epicycle's] center…Therefore, having become aware of these [defects], I often considered whether there could perhaps be found a more reasonable arrangement of circles, from which every apparent irregularity would be derived while everything in itself would move uniformly, as is required by the rule of perfect motion. (MW 81).
Goddu (381–84) has plausibly maintained that while the initial motivation for Copernicus was dissatisfaction with the equant, that dissatisfaction may have impelled him to observe other violations of uniform circular motion, and those observations, not the rejection of the equant by itself, led to the heliocentric theory. Blumenberg (254) has pointed out that the mobility of the earth may have been reinforced by the similarity of its spherical shape to those of the heavenly bodies.
As the rejection of the equant suggests a return to the Aristotelian demand for true uniform circular motion of the heavenly bodies, it is unlikely that Copernicus adopted the heliocentric model because philosophies popular among Renaissance humanists like Neoplatonism and Hermetism compelled him in that direction.[6] Nor should we attribute Copernicus's desire for uniform circular motions to an aesthetic need, for this idea was philosophical not aesthetic, and Copernicus's replacing the equant with epicyclets made his system more complex than Ptolemy's. Most importantly, we should bear in mind what Swerdlow and Neugebauer (59) asserted:
Copernicus arrived at the heliocentric theory by a careful analysis of planetary models — and as far as is known, he was the only person of his age to do so — and if he chose to adopt it, he did so on the basis of an equally careful analysis.
In the Commentariolus Copernicus listed assumptions that he believed solved the problems of ancient astronomy. He stated that the earth is only the center of gravity and center of the moon's orbit; that all the spheres encircle the sun, which is close to the center of the universe; that the universe is much larger than previously assumed, and the earth's distance to the sun is a small fraction of the size of the universe; that the apparent motion of the heavens and the sun is created by the motion of the earth; and that the apparent retrograde motion of the planets is created by the earth's motion. Although the Copernican model maintained epicycles moving along the deferrent, which explained retrograde motion in the Ptolemaic model, Copernicus correctly explained that the retrograde motion of the planets was only apparent not real, and its appearance was due to the fact that the observers were not at rest in the center. The work dealt very briefly with the order of the planets (Mercury, Venus, earth, Mars, Jupiter, and Saturn, the only planets that could be observed with the naked eye), the triple motion of the earth (the daily rotation, the annual revolution of its center, and the annual revolution of its inclination) that causes the sun to seem to be in motion, the motions of the equinoxes, the revolution of the moon around the earth, and the revolution of the five planets around the sun.
2.3 On the Revolutions
The Commentariolus was only intended as an introduction to Copernicus's ideas, and he wrote “the mathematical demonstrations intended for my larger work should be omitted for brevity's sake…” (MW 82). In a sense it was an announcement of the greater work that Copernicus had begun. The Commentariolus was never published during Copernicus's lifetime, but he sent manuscript copies to various astronomers and philosophers. He received some discouragement because the heliocentric system seemed to disagree with the Bible, but mostly he was encouraged. Although Copernicus's involvement with official attempts to reform the calendar was limited to a no longer extant letter, that endeavor made a new, serious astronomical theory welcome. Fear of the reaction of ecclesiastical authorities was probably the least of the reasons why he delayed publishing his book.[7] The most important reasons for the delay was that the larger work required both astronomical observations and intricate mathematical proofs. His administrative duties certainly interfered with both the research and the writing. He was unable to make the regular observations that he needed and Frombork, which was often fogged in, was not a good place for those observations. Moreover, as Gingerich (1993, 37) pointed out,
[Copernicus] was far from the major international centers of printing that could profitably handle a book as large and technical as De revolutionibus. On the other [hand], his manuscript was still full of numerical inconsistencies, and he knew very well that he had not taken complete advantage of the opportunities that the heliocentric viewpoint offered…Furthermore, Copernicus was far from academic centers, thereby lacking the stimulation of technically trained colleagues with whom he could discuss his work.
The manuscript of On the Revolutions was basically complete when Rheticus came to visit him in 1539. The work comprised six books. The first book, the best known, discussed what came to be known as the Copernican theory and what is Copernicus's most important contribution to astronomy, the heliocentric universe (although in Copernicus's model, the sun is not truly in the center). Book 1 set out the order of the heavenly bodies about the sun: “[The sphere of the fixed stars] is followed by the first of the planets, Saturn, which completes its circuit in 30 years. After Saturn, Jupiter accomplishes its revolution in 12 years. The Mars revolves in 2 years. The annual revolution takes the series' fourth place, which contains the earth…together with the lunar sphere as an epicycle. In the fifth place Venus returns in 9 months. Lastly, the sixth place is held by Mercury, which revolves in a period of 80 days” (Revolutions, 21–22). This established a relationship between the order of the planets and their periods, and it made a unified system. This may be the most important argument in favor of the heliocentric model as Copernicus described it.[8] It was far superior to Ptolemy's model, which had the planets revolving around the earth so that the sun, Mercury, and Venus all had the same annual revolution. In book 1 Copernicus also insisted that the movements of all bodies must be circular and uniform, and noted that the reason they may appear nonuniform to us is “either that their circles have poles different [from the earth's] or that the earth is not at the center of the circles on which they revolve” (Revolutions, 11). Particularly notable for Copernicus was that in Ptolemy's model the sun, the moon, and the five planets seemed ironically to have different motions from the other heavenly bodies and it made more sense for the small earth to move than the immense heavens. But the fact that Copernicus turned the earth into a planet did not cause him to reject Aristotelian physics, for he maintained that “land and water together press upon a single center of gravity; that the earth has no other center of magnitude; that, since earth is heavier, its gaps are filled with water…” (Revolutions, 10). As Aristotle had asserted, the earth was the center toward which the physical elements gravitate. This was a problem for Copernicus's model, because if the earth was no longer the center, why should elements gravitate toward it?
The second book of On the Revolutions elaborated the concepts in the first book; book 3 dealt with the precession of the equinoxes and solar theory; book 4 dealt with the moon's motions; book 5 dealt with the planetary longitude and book 6 with latitude.[9] Copernicus depended very much on Ptolemy's observations, and there was little new in his mathematics. He was most successful in his work on planetary longitude, which, as Swerdlow and Neugebauer (77) commented, was “Copernicus's most admirable, and most demanding, accomplishment…It was above all the decision to derive new elements for the planets that delayed for nearly half a lifetime Copernicus's continuation of his work — nearly twenty years devoted to observation and then several more to the most tedious kind of computation — and the result was recognized by his contemporaries as the equal of Ptolemy's accomplishment, which was surely the highest praise for an astronomer.” Surprisingly, given that the elimination of the equant was so important in the Commentariolus, Copernicus did not mention it in book 1, but he sought to replace it with an epicyclet throughout On the Revolutions. Nevertheless, he did write in book 5 when describing the motion of Mercury:
…the ancients allowed the epicycle to move uniformly only around the equant's center. This procedure was in gross conflict with the true center [of the epicycle's motion], its relative [distances], and the prior centers of both [other circles]…However, in order that this last planet too may be rescued from the affronts and pretenses of its detractors, and that its uniform motion, no less than that of the other aforementioned planets, may be revealed in relation to the earth's motion, I shall attribute to it too, [as the circle mounted] on its eccentric, an eccentric instead of the epicycle accepted in antiquity (Revolutions, 278–79).
2.4 Rheticus and the Narratio prima
Although Copernicus received encouragement to publish his book from his close friend, the bishop of Chelmo Tiedemann Giese (1480–1550), and from the cardinal of Capua Nicholas Schönberg (1472–1537), it was the arrival of Georg Joachim Rheticus in Frombork that solved his needs for a supportive and stimulating colleague in mathematics and astronomy and for access to an appropriate printer. Rheticus was a professor of mathematics at the University of Wittenberg, a major center for the student of mathematics as well as for Lutheran theology. In 1538 Rheticus took a leave of absence to visit several famous scholars in the fields of astronomy and mathematics. It is not known how Rheticus learned about Copernicus's theory; he may have been convinced to visit Copernicus by one of the earlier scholars he had visited, Johann Schöner, though, as Swerdlow and Neugebauer (16) noted, by “the early 1530's knowledge of Copernicus's new theory was circulating in Europe, even reaching the high and learned circles of the Vatican.” Rheticus brought with him some mathematical and astronomical volumes, which both provided Copernicus with some important material and showed him the quality of the mathematical printing available in the German centers of publishing.[10] Rheticus's present of the 1533 edition of Regiomontanus's On all Kinds of Triangles (De triangulis omnimodis), for example, convinced Copernicus to revise his section on trigonometry. But Rheticus was particularly interested in showing Copernicus the work of the Nuremberg publisher Johann Petreius as a possible publisher of Copernicus's volume. Swerdlow and Neugebauer (25) plausibly suggested that “Petreius was offering to publish Copernicus's work, if not advertising by this notice that he was already committed to do so.” Rheticus wrote the Narratio prima in 1540, an introduction to the theories of Copernicus, which was published and circulated. This further encouraged Copernicus to publish his Revolutions, which he had been working on since he published the Commentariolus.
The Narratio prima was written in 1539 and took the form of a letter to Johann Schöner announcing Copernicus's findings and describing the contents of the Revolutions. He dealt with such topics as the motions of the fixed stars, the tropical year, the obliquity of the ecliptic, the problems resulting from the motion of the sun, the motions of the earth and the other planets, librations, longitude in the other five planets, and the apparent deviation of the planets from the ecliptic. He asserted that the heliocentric universe should have been adopted because it better accounted for such phenomena as the precession of the equinoxes and the change in the obliquity of the ecliptic; it resulted in a diminution of the eccentricity of the sun; the sun was the center of the deferents of the planets; it allowed the circles in the universe to revolve uniformly and regularly; it satisfied appearances more readily with fewer explanations necessary; it united all the spheres into one system. Rheticus added astrological predictions and number mysticism, which were absent from Copernicus's work.
The Narratio prima was printed in 1540 in Gdansk (then Danzig); thus, it was the first printed description of the Copernican thesis. Rheticus sent a copy to Achilles Pirmin Gasser of Feldkirch, his hometown in modern-day Austria, and Gasser wrote a foreword that was published with a second edition that was produced in 1541 in Basel. It was published again in 1596 as an appendix to the first edition of Johannes Kepler's Mysterium cosmographicum (Secret of the Universe), the first completely Copernican work by an adherent since the publications by Copernicus and Rheticus.
2.5 Printing On the Revolutions and Osiander's Preface
The publication of Rheticus's Narratio prima did not create a big stir against the heliocentric thesis, and so Copernicus decided to publish On the Revolutions. He added a dedication to Pope Paul III (r. 1534–1549), probably for political reasons, in which he expressed his hesitancy about publishing the work and the reasons he finally decided to publish it. He gave credit to Schönberg and Giese for encouraging him to publish and omitted mention of Rheticus, but it would have been insulting to the pope during the tense period of the Reformation to give credit to a Protestant minister.[11] He dismissed critics who might have claimed that it was against the Bible by giving the example of the fourth-century Christian apologist Lactantius, who had rejected the spherical shape of the earth, and by asserting, “Astronomy is written for astronomers” (Revolutions, 5). In other words, theologians should not meddle with it. He pointed to the difficulty of calendar reform because the motions of the heavenly bodies were inadequately known. And he called attention to the fact that “if the motions of the other planets are correlated with the orbiting of the earth, and are computed for the revolution of each planet, not only do their phenomena follow therefrom but also the order and size of all the planets and spheres, and heaven itself is so linked together that in no portion of it can anything be shifted without disrupting the remaining parts and the universe as a whole” (Revolutions, 5).
Rheticus returned to Wittenberg in 1541 and the following year received another leave of absence, at which time he took the manuscript of the Revolutions to Petreius for publishing in Nuremberg. Rheticus oversaw the printing of most of the text. However, Rheticus was forced to leave Nuremberg later that year because he was appointed professor of mathematics at the University of Leipzig. He left the rest of the management of printing the Revolutions to Andrew Osiander (1498–1552), a Lutheran minister who was also interested in mathematics and astronomy. Though he saw the project through, Osiander appended an anonymous preface to the work. In it he claimed that Copernicus was offering a hypothesis, not a true account of the working of the heavens: “Since he [the astronomer] cannot in any way attain to the true causes, he will adopt whatever suppositions enable the motions to be computed correctly from the principles of geometry for the future as well as for the past …these hypotheses need not be true nor even probable” (Revolutions, xvi). This clearly contradicted the body of the work. Both Rheticus and Giese protested, and Rheticus crossed it out in his copy.
2.6 Sixteenth Century Reactions to On the Revolutions
Copernicus's fame and book made its way across Europe over the next fifty years, and a second edition was brought out in 1566.[12] As Gingerich's census of the extant copies showed, the book was read and commented on by astronomers. Gingerich (2004, 55) noted “the majority of sixteenth-century astronomers thought eliminating the equant was Copernicus' big achievement.”
While Martin Luther may have made negative comments about Copernicus because the idea of the heliocentric universe seemed to contradict the Bible,[13] Philip Melanchthon (1497–1560), who presided over the curriculum at the University of Wittenberg, eventually accepted the importance of teaching Copernicus's ideas, perhaps because Osiander's preface made the work more palatable. His son-in-law Caspar Peucer (1525-1602) taught astronomy there and began teaching Copernicus's work. As a result, the University of Wittenberg became a center where Copernicus's work was studied. But Rheticus was the only Wittenberg scholar who accepted the heliocentric idea. Robert Westman (1975a, 166–67) suggested that there was a ‘Wittenberg Interpretation’: astronomers appreciated and adopted some of Copernicus's mathematical models but rejected his cosmology, and some were pleased with his replacement of the equant by epicyclets. One of these was Erasmus Reinhold (1511–1553), a leading astronomer at Wittenberg who became dean and rector. He produced a new set of planetary tables from Copernicus's work, the Prutenic Tables. Although, as Gingerich (1993, 232) pointed out, “there was relatively little to distinguish between the accuracy of the Alfonsine Tables and the Prutenic Tables,” the latter were more widely adopted; Gingerich plausibly suggested that the fact that the Prutenic Tables more accurately predicted a conjunction between Jupiter and Saturn in 1563 made the difference. Reinhold did not accept the heliocentric theory, but he admired the elimination of the equant. The Prutenic Tables excited interest in Copernicus's work.
Tycho Brahe (1546–1601) was the greatest astronomical observer before the invention of the telescope. He called Copernicus a ‘second Ptolemy’ (quoted in Westman 1975, 307) and appreciated both the elimination of the equant and the creation of a planetary system. But Tycho could not adopt the Copernican system, partly for the religious reason that it went against what the Bible seemed to preach. He, therefore, adopted a compromise, the ‘geoheliostatic’ system in which the two inner planets revolved around the sun and that system along with the rest of the planets revolved around the earth.
Among Catholics, Christoph Clavius (1537–1612) was the leading astronomer in the sixteenth century. A Jesuit himself, he incorporated astronomy into the Jesuit curriculum and was the principal scholar behind the creation of the Gregorian calendar. Like the Wittenberg astronomers, Clavius adopted Copernican mathematical models when he felt them superior, but he believed that Ptolemy's cosmology — both his ordering of the planets and his use of the equant — was correct.
Pope Clement VII (r. 1523–1534) had reacted favorably to a talk about Copernicus's theories, rewarding the speaker with a rare manuscript. There is no indication of how Pope Paul III, to whom On the Revolutions was dedicated reacted; however, a trusted advisor, Bartolomeo Spina of Pisa (1474–1546) intended to condemn it but fell ill and died before his plan was carried out (see Rosen, 1975). Thus, in 1600 there was no official Catholic position on the Copernican system, and it was certainly not a heresy. When Giordano Bruno (1548–1600) was burned at the stake as a heretic, it had nothing to do with his writings in support of Copernican cosmology, and this is clearly shown in Finocchiaro's reconstruction of the accusations against Bruno (see also Blumenberg's part 3, chapter 5, titled “Not a Martyr for Copernicanism: Giordano Bruno”).
Michael Maestlin (1550–1631) of the University of Tübingen was the earliest astronomer after Rheticus to adopt Copernicus's heliocentricism. Although he wrote a popular textbook that was geocentric, he taught his students that the heliocentric system was superior. He also rejected Osiander's preface. Maestlin's pupil Johannes Kepler wrote the first book since the publication of On the Revolutions that was openly heliocentric in its orientation, the Mysterium cosmographicum (Secret of the Universe). And, of course, Kepler eventually built on Copernicus's work to create a much more accurate description of the solar system.
Bibliography
A. Complete Works of Copernicus
In 1972 the Polish Academy of Sciences under the direction of J. Dobrzycki published critical editions of the Complete Works of Copernicus in six languages: Latin, English, French, German, Polish, and Russian. The first volume was a facsimile edition. The annotations in the English translations are more comprehensive than the others. The English edition was reissued as follows:
Minor Works, 1992, trans. E. Rosen, Baltimore: The Johns Hopkins University Press (originally published as volume 3 of Nicholas Copernicus: Complete Works, Warsaw: Polish Scientific Publishers, 1985). Referred to herein as MW.
On the Revolutions, 1992, trans. E. Rosen, Baltimore: The Johns Hopkins University Press (originally published as volume 2 of Nicholas Copernicus: Complete Works, Warsaw: Polish Scientific Publishers, 1978). Referred to herein as Revolutions.
B. Other Translations of Copernicus's Works
On the Revolutions of the Heavenly Spheres, 1955, trans. C.G. Wallis, vol. 16 of Great Books of the Western World, Chicago: Encyclopedia Britannica; 1995, reprint, Amherst: Prometheus Books.
On the Revolutions of the Heavenly Spheres, 1976, trans. and ed. A.M. Duncan, Newton Abbot: David & Charles.
“The Derivation and First Draft of Copernicus's Planetary Theory: A Translation of the Commentariolus with Commentary,” 1973, trans. N.M. Swerdlow, Proceedings of the American Philosophical Society, 117: 423–512.
C. Translations of Other Primary Sources
Bruno, G., 1977, The Ash Wednesday Supper, trans. E.A. Gosselin and L.S. Lerner, Hamden: Archon Books, 1995; reprint, Toronto: University of Toronto Press.
Rheticus, G.J., Narratio prima, in E. Rosen, 1971, 107–96.
D. Secondary Sources
Blumenberg, H., 1987, The Genesis of the Copernican World, trans. R.M. Wallace, Cambridge, MA: MIT Press.
Cohen, I.B., 1960, The Birth of a New Physics, Garden City: Anchor Books; rev. ed., New York: W.W. Norton, 1985.
–––, 1985, Revolutions in Science, Cambridge, MA: Harvard University Press.
Crowe, M.J., 1990, Theories of the World from Antiquity to the Copernican Revolution, New York: Dover Publications.
Finocchiaro, M.A., 2002, “Philosophy versus Religion and Science versus Religion: the Trials of Bruno and Galileo,” in H. Gatti (ed.), 51–96.
Gatti, H. (ed.), 2002, Giordano Bruno: Philosopher of the Renaissance, Aldershot: Ashgate.
Gillespie, C.C. (ed.), 1970–80, Dictionary of Scientific Biography, New York: Scribner's.
Gingerich, O., 1993, The Eye of Heaven: Ptolemy, Copernicus, Kepler, New York: American Institute of Physics.
–––, 2002, An Annotated Census of Copernicus' De revolutionibus, Leiden: Brill Academic Publishers; Nuremberg, 1543 and Basel, 1566.
–––, 2004, The Book Nobody Read: Chasing the Revolutions of Nicolaus Copernicus, New York: Walker & Company.
Goddu, A., 2010, Copernicus and the Aristotelian Tradition: Education, Reading, and Philosophy in Copernicus's Path to Heliocentrism, Leiden: Brill.
Grendler, P., 2002, The Universities of the Italian Renaissance, Baltimore: The Johns Hopkins University Press.
Hallyn, F., 1990, The Poetic Structure of the World: Copernicus and Kepler, trans. D. Leslie, New York: Zone Books.
Koestler, A., 1989, The Sleepwalkers, London: Penguin, reprint of 1959 edition.
Koyré, A., 1957, From the Closed World to the Infinite Universe, Baltimore: The Johns Hopkins University Press.
–––, 1973, The Astronomical Revolution: Copernicus, Kepler, Borelli, trans. R.E.W. Maddison, Ithaca: Cornell University Press.
Kuhn, T., 1957, The Copernican Revolution, Cambridge, MA: Harvard University Press.
Ragep, F.J., 2005, “Ali Qushji and Regiomontanus,” Journal for the History of Astronomy, 36: 359–71.
–––, 2007, “Copernicus and His Islamic Predecessors,” History of Science, 45: 65–81.
Rosen, E.,1970a, “Copernicus,” in Gillespie (ed.), 3: 401–11.
–––, 1970b, “Rheticus,” Gillespie (ed.), 11: 395–97.
–––, 1971, Three Copernican Treatises, 3d ed., New York: Octagon Books.
–––, 1975, “Was Copernicus' Revolutions Approved by the Pope?” Journal of the History of Ideas, 36: 531–42.
–––, 1984, Copernicus and the Scientific Revolution, Malabar, FL: Krieger Publishing Co.
Saliba, G., 2007, Islamic Science and the Making of the European Renaissance, Cambridge, MA: MIT Press.
Shumaker, W., 1979, The Occult Sciences in the Renaissance: A Study in Intellectual Patterns, Berkeley: University of California Press, reprint of 1972 edition.
Siraisi, N., 1981, Taddeo Alderotti and His Pupils: Two Generations of Italian Medical Learning, Princeton: Princeton University Press.
–––, 1990, Medieval and Early Renaissance Medicine: An Introduction to Knowledge and Practice, Chicago: University of Chicago Press.
Swerdlow, N., 2000, “Copernicus, Nicolaus (1473–1543),” in Encyclopedia of the Scientific Revolution, W. Applebaum (ed.), New York: Garland Publishing, 162–68.
Swerdlow, N. and O. Neugebauer, 1984, Mathematical Astronomy in Copernicus's De Revolutionibus, 2 vols., New York: Springer-Verlag.
Westman, R., 1975a, “The Melanchthon Circle, Rheticus, and the Wittenberg Interpretation of the Copernican Theory,” Isis, 66: 165–93.
–––, 1975b, “Three Responses to the Copernican Theory: Johannes Praetorius, Tycho Brahe, and Michael Maestlin,” in Westman (ed.), 1975c.
–––, (ed), 1975c, The Copernican Achievement, Berkeley: University of California Press.
–––, 1993, “Copernicus and the Prognosticators: The Bologna Period, 1496–1500,” Universitas, 5 (December): 1–5.
Yates, F., 1979, Giordano Bruno and the Hermetic Tradition, Chicago: University of Chicago Press, reprint of 1964 edition.
Thursday, August 19, 2010
NASA: Astronauts Say Tricky Space Station Repair A Success
From Space.com:
Astronauts Say Tricky Space Station Repair a Success
By Denise Chow
SPACE.com Staff Writer
posted: 19 August 2010
03:16 pm ET
Astronauts living on the International Space Station said Thursday that their orbiting lab is finally back in action after a series of tricky spacewalks to replace a broken coolant pump.
American astronauts Douglas Wheelock, Tracy Caldwell Dyson and Shannon Walker lauded the efforts of engineers on Earth to help them restore the station's cooling system to full strength after a vital pump module failed July 31. The astronauts performed three challenging spacewalks this month to make the repairs.
"As far as we can tell, things are coming back up nominally," Caldwell Dyson said, adding that the station's U.S, Japanese and European labs are up and running. "We've got most of our lab back ... so, to us here on orbit, things are looking better than normal."
Ads by GoogleDavid H. Adams, MDExpert Heart Valve Repair What Every Patient Should Know
www.MitralValveRepair.orgTiffany Business AccountsNow is the time to remember valued employees & important clients.
www.Tiffany.comThe space station is home to six astronauts; three Americans and three Russians.
Emergency space station repairs
During three spacewalks, Wheelock and Caldwell Dyson removed the faulty ammonia pump and replaced it with one of four spares stored on the exterior of the International Space Station. Walker operated the robotic arm from inside the space station. [Graphic: The International Space Station Explained]
"It demonstrates how we can respond in an emergency," Walker said during the interview with CBS News broadcast on NASA TV. "I think it was really NASA at its finest to get this repair done in short order."
And while these types of major repairs could become more complicated following the retirement of NASA's space shuttle fleet, the ability for the ground controllers and station astronauts to mobilize and complete such a task in a short timeframe highlights the strong cooperative effort of those involved, the astronauts said.
"It was a validation of our teamwork, our training and everyone involved," Wheelock said. "The way everything came together was a great lesson in teamwork. I think the confidence is real high on the team as we press forward."
Practice makes space perfect
To plan and practice the spacewalks ahead of missions, astronauts rehearse the skills and maneuvers in the Neutral Buoyancy Laboratory (NBL), a huge underwater tank at Johnson Space Center in Houston.
"Our training in the NBL back in Houston is skills-based," Wheelock explained. "And those skills came in very handy. But when you get outside with the temperature changes and the pure vacuum out there, things don't behave as they do on Earth. We have to be ready for those things."
For Walker, that meant remaining confident in her expertise at operating the station's robotic arm.
"Just like with the spacewalk operations, I was trained sort of generically," Walker said. "With the final EVA, I didn't get the procedures until the day of."
During the first spacewalk, a stuck ammonia hose, and later an ammonia leak, gave Wheelock and Caldwell Dyson some trouble when it refused to budge.
"I think the greatest thing that I learned on my earlier EVAs (extravehicular activities) is just to expect that," Wheelock said. "Just take a deep breath, think of the different ways that you can finesse the piece of hardware, and listen to what the trainers are telling you on the ground. And don't give up trying."
For the spacewalkers, the stubborn hose acted as their nemesis, said Wheelock.
"We needed a villain to fight against when we were out there," he said. "But we were able to rise to the challenge as a team."
Unforgettable spacewalks
The set of three EVAs will likely resonate with Caldwell Dyson, as they were her first spacewalks. Amid the demanding tasks, she took time to reflect on the significance of the situation, and described the experience as "awe-inspiring."
"The first EVA was a culmination of 12 years of training," Caldwell Dyson said. "It was a culmination of so much desire and years of training that it's a feeling I'll never forget.
The station is slated to keep flying through at least 2020, so spare parts will be a major concern once NASA's space shuttles stop flying next year.
NASA currently plans to fly two final shuttle missions (in November of this year and February 2011) before retiring its three-shuttle fleet for good. The possible addition of a third shuttle flight is being discussed by lawmakers.
Astronauts Say Tricky Space Station Repair a Success
By Denise Chow
SPACE.com Staff Writer
posted: 19 August 2010
03:16 pm ET
Astronauts living on the International Space Station said Thursday that their orbiting lab is finally back in action after a series of tricky spacewalks to replace a broken coolant pump.
American astronauts Douglas Wheelock, Tracy Caldwell Dyson and Shannon Walker lauded the efforts of engineers on Earth to help them restore the station's cooling system to full strength after a vital pump module failed July 31. The astronauts performed three challenging spacewalks this month to make the repairs.
"As far as we can tell, things are coming back up nominally," Caldwell Dyson said, adding that the station's U.S, Japanese and European labs are up and running. "We've got most of our lab back ... so, to us here on orbit, things are looking better than normal."
Ads by GoogleDavid H. Adams, MDExpert Heart Valve Repair What Every Patient Should Know
www.MitralValveRepair.orgTiffany Business AccountsNow is the time to remember valued employees & important clients.
www.Tiffany.comThe space station is home to six astronauts; three Americans and three Russians.
Emergency space station repairs
During three spacewalks, Wheelock and Caldwell Dyson removed the faulty ammonia pump and replaced it with one of four spares stored on the exterior of the International Space Station. Walker operated the robotic arm from inside the space station. [Graphic: The International Space Station Explained]
"It demonstrates how we can respond in an emergency," Walker said during the interview with CBS News broadcast on NASA TV. "I think it was really NASA at its finest to get this repair done in short order."
And while these types of major repairs could become more complicated following the retirement of NASA's space shuttle fleet, the ability for the ground controllers and station astronauts to mobilize and complete such a task in a short timeframe highlights the strong cooperative effort of those involved, the astronauts said.
"It was a validation of our teamwork, our training and everyone involved," Wheelock said. "The way everything came together was a great lesson in teamwork. I think the confidence is real high on the team as we press forward."
Practice makes space perfect
To plan and practice the spacewalks ahead of missions, astronauts rehearse the skills and maneuvers in the Neutral Buoyancy Laboratory (NBL), a huge underwater tank at Johnson Space Center in Houston.
"Our training in the NBL back in Houston is skills-based," Wheelock explained. "And those skills came in very handy. But when you get outside with the temperature changes and the pure vacuum out there, things don't behave as they do on Earth. We have to be ready for those things."
For Walker, that meant remaining confident in her expertise at operating the station's robotic arm.
"Just like with the spacewalk operations, I was trained sort of generically," Walker said. "With the final EVA, I didn't get the procedures until the day of."
During the first spacewalk, a stuck ammonia hose, and later an ammonia leak, gave Wheelock and Caldwell Dyson some trouble when it refused to budge.
"I think the greatest thing that I learned on my earlier EVAs (extravehicular activities) is just to expect that," Wheelock said. "Just take a deep breath, think of the different ways that you can finesse the piece of hardware, and listen to what the trainers are telling you on the ground. And don't give up trying."
For the spacewalkers, the stubborn hose acted as their nemesis, said Wheelock.
"We needed a villain to fight against when we were out there," he said. "But we were able to rise to the challenge as a team."
Unforgettable spacewalks
The set of three EVAs will likely resonate with Caldwell Dyson, as they were her first spacewalks. Amid the demanding tasks, she took time to reflect on the significance of the situation, and described the experience as "awe-inspiring."
"The first EVA was a culmination of 12 years of training," Caldwell Dyson said. "It was a culmination of so much desire and years of training that it's a feeling I'll never forget.
The station is slated to keep flying through at least 2020, so spare parts will be a major concern once NASA's space shuttles stop flying next year.
NASA currently plans to fly two final shuttle missions (in November of this year and February 2011) before retiring its three-shuttle fleet for good. The possible addition of a third shuttle flight is being discussed by lawmakers.
Saturday, August 7, 2010
Solar Tsunami Revealed In New Photo
from Space.com:
Solar Tsunami Revealed in New Photo
By SPACE.com Staff
posted: 06 August 2010
05:46 pm ET
A vivid new photo of the sun has revealed a new view of a solar eruption in the star's northern hemisphere that blasted charged particles in Earth's direction this week, according to NASA officials.
The solar storm, which NASA called a "solar tsunami" in a Friday statement, occurred Aug. 1. It was a Class C3 solar flare in which almost the entire Earth-facing side of the sun erupted in a wave of tumultuous activity. [New solar tsunami photo.]
The solar particles began striking Earth's magnetic field Tuesday and sparked a powerful 12-hour geomagnetic storm and spectacular aurora displays. The flare was not powerful enough to pose a radiation threat to astronauts living on the International Space Station, NASA officials have said.
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www.ctsolar.comThis new multi-wavelength extreme ultraviolet photo from NASA's Solar Dynamics Observatory shows the sun in mid-eruption.
The flare is visible as the white area on the upper left, and the ensuing solar tsunami is the wave-like structure in the upper right. Magnetic filaments can also be seen coming off the surface of the sun.
The different colors in the image represent different temperatures of gas.
The eruption, called a coronal mass ejection, was spotted by NASA's Solar Dynamics Observatory , which captures high-definition views of the sun at a variety of wavelengths. SDO was launched in February and peers deep into the layers of the sun, investigating the mysteries of its inner workings.
Analysts believe a second solar flare could come on the heels of the first flare, and could re-energize the fading geomagnetic storm and spark a new round of bright aurora displays.
Solar Tsunami Revealed in New Photo
By SPACE.com Staff
posted: 06 August 2010
05:46 pm ET
A vivid new photo of the sun has revealed a new view of a solar eruption in the star's northern hemisphere that blasted charged particles in Earth's direction this week, according to NASA officials.
The solar storm, which NASA called a "solar tsunami" in a Friday statement, occurred Aug. 1. It was a Class C3 solar flare in which almost the entire Earth-facing side of the sun erupted in a wave of tumultuous activity. [New solar tsunami photo.]
The solar particles began striking Earth's magnetic field Tuesday and sparked a powerful 12-hour geomagnetic storm and spectacular aurora displays. The flare was not powerful enough to pose a radiation threat to astronauts living on the International Space Station, NASA officials have said.
Ads by GoogleBuild Solar PanelsGet Free Plans And Details On How To Build Your Own Home Solar Panels
ReviewGreenEnergy.comLaptop Solar SolutionsExpedition grade systems Used on every continent worldwide
www.ctsolar.comThis new multi-wavelength extreme ultraviolet photo from NASA's Solar Dynamics Observatory shows the sun in mid-eruption.
The flare is visible as the white area on the upper left, and the ensuing solar tsunami is the wave-like structure in the upper right. Magnetic filaments can also be seen coming off the surface of the sun.
The different colors in the image represent different temperatures of gas.
The eruption, called a coronal mass ejection, was spotted by NASA's Solar Dynamics Observatory , which captures high-definition views of the sun at a variety of wavelengths. SDO was launched in February and peers deep into the layers of the sun, investigating the mysteries of its inner workings.
Analysts believe a second solar flare could come on the heels of the first flare, and could re-energize the fading geomagnetic storm and spark a new round of bright aurora displays.
Thursday, August 5, 2010
A Guide For Watching Auroras
From OurAmazingPlanet:
A Guide for Watching Earth's Auroras Aug 4, 2010 4:33 PM ET By Joe Rao, OurAmazingPlanet Contributor
The snaking green glow of an aurora photographed earlier this year by astronauts aboard the International Space Station. Credit: NASA
In the dark of the night, far from lights, when the moon is down, you may see an eerie glow in the sky, now here, now there, shifting silently from place to place.
Ads by GoogleRealAge® Official SiteYou still haven't taken the free test to learn your biological age?RealAge.comStructural&Steel Productsguardrail, light poles, overhead structures, sports lighting - Texaswww.s-steel.comLiberty Solar SolutionsSolar Electric Installations Arkansas Solar Rebate Now Availablewww.LibertySolarSolutions.comOften, its color appears whitish, but occasionally it's a startling red or green. Sometimes it appears as streamers, or as curtains waving in an immense breeze. These streamers of light are a display of the aurora borealis, also known as the northern lights (and southern lights).
While northern lights are usually visible only from the far north, around or above the Arctic circle, during a strong space storm they are commonly spotted in southern Canada and the far northern reaches of the United States. On very rare occasions, they can be visible as far south as Texas. Very dark skies away from city lights are needed to see the aurora.
There's no way to pinpoint precisely where to watch and no time table for when they might appear at any specific place on Earth. But there are certain signs you can watch for. [Read tips for spotting auroras here.]
Solar signs
If news reports say that shortwave radio communications have been disturbed or interrupted, and especially if scientists say it had to do with something happening on the sun, then, that night, the next night and even the next, get out away from city lights and look up generally toward the north.
These conditions are actually happening right now: The sun's surface erupted early on Sunday, and auroras have been visible to people at high northern latitudes.
Solar astronomers observe the sun daily and continually. Special techniques allow these specialists to detect explosions on the sun's surface, called flares. These explosions can range from weak to stupendous.
Flare meets atmosphere
From Earth's vantage point, a flare is a rather sudden brightening of an area near or among sunspots, which themselves are cooler, darker spots on the sun. A small flare might brighten for 20 minutes and then take another 40 to 60 minutes to fade. A great flare may take an hour or more to brighten, not fading away until 3 or 4 hours later. A flare is noticed as a brightening in the ultraviolet and X-ray parts of the spectrum, as well as in visible light.
Auroral displays occur in the outer stretches of the Earth's atmosphere, specifically in a region called the ionosphere, which runs from about 60 to 600 miles (96 to 960 km) above the Earth's surface. At these heights, air molecules are so far apart that space is practically empty like a vacuum, or the inside of a fluorescent tube.
Whenever the sun experiences a significant flare, great streams of charged particles — protons and electrons — stream toward Earth at terrific speeds; when they hit Earth's atmosphere, they clash with the molecules and atoms of the rarefied gases of the upper atmosphere. These atoms are temporarily stripped of some of their electrons by these collisions and absorb energy in the process. Such charged atoms are called ions. Within a millionth of a second the atoms regain their lost electrons and re-emit this energy in the form of light of various colors.
The electrons that are lost fly around as negatively charged particles. All the extra ions and electrons swirling arund in the atmosphere are responsible for the shortwave and CB skip changes that clue us in to the impending auroral displays.
Northern and southern lights
Actually there is always an overload of electrified particles being sent to Earth, but after taking about 20 to 30 hours to traverse the 93 million miles (150 million kilometers) between the Sun and the Earth, they have become very much affected by Earth's magnetic field. Instead of penetrating any part of the atmosphere, they flow toward the regions of the north and south magnetic poles where the night sky glows eternally with solar overcharge. The aurora at the northern magnetic pole is called aurora borealis, while the ones at the southern pole are called aurora australis (or "southern lights").
Auroras can manifest in many different types of displays: Arcs of light can extend for hundreds of miles or kilometers and start at the horizon and spread upward; long, thin streamers and rays extend toward the zenith and form curtains of light.
Green is the most commonly seen color during major displays; it is caused by the ionization of atomic oxygen. The red colors also often seen are caused by the ionization of molecular oxygen and nitrogen.
Auroral displays appear to be most frequent at the time of greatest sunspot activity. We are now seeing a slow rise toward a peak in sunspot activity which is now expected sometime around the year 2013.
A Guide for Watching Earth's Auroras Aug 4, 2010 4:33 PM ET By Joe Rao, OurAmazingPlanet Contributor
The snaking green glow of an aurora photographed earlier this year by astronauts aboard the International Space Station. Credit: NASA
In the dark of the night, far from lights, when the moon is down, you may see an eerie glow in the sky, now here, now there, shifting silently from place to place.
Ads by GoogleRealAge® Official SiteYou still haven't taken the free test to learn your biological age?RealAge.comStructural&Steel Productsguardrail, light poles, overhead structures, sports lighting - Texaswww.s-steel.comLiberty Solar SolutionsSolar Electric Installations Arkansas Solar Rebate Now Availablewww.LibertySolarSolutions.comOften, its color appears whitish, but occasionally it's a startling red or green. Sometimes it appears as streamers, or as curtains waving in an immense breeze. These streamers of light are a display of the aurora borealis, also known as the northern lights (and southern lights).
While northern lights are usually visible only from the far north, around or above the Arctic circle, during a strong space storm they are commonly spotted in southern Canada and the far northern reaches of the United States. On very rare occasions, they can be visible as far south as Texas. Very dark skies away from city lights are needed to see the aurora.
There's no way to pinpoint precisely where to watch and no time table for when they might appear at any specific place on Earth. But there are certain signs you can watch for. [Read tips for spotting auroras here.]
Solar signs
If news reports say that shortwave radio communications have been disturbed or interrupted, and especially if scientists say it had to do with something happening on the sun, then, that night, the next night and even the next, get out away from city lights and look up generally toward the north.
These conditions are actually happening right now: The sun's surface erupted early on Sunday, and auroras have been visible to people at high northern latitudes.
Solar astronomers observe the sun daily and continually. Special techniques allow these specialists to detect explosions on the sun's surface, called flares. These explosions can range from weak to stupendous.
Flare meets atmosphere
From Earth's vantage point, a flare is a rather sudden brightening of an area near or among sunspots, which themselves are cooler, darker spots on the sun. A small flare might brighten for 20 minutes and then take another 40 to 60 minutes to fade. A great flare may take an hour or more to brighten, not fading away until 3 or 4 hours later. A flare is noticed as a brightening in the ultraviolet and X-ray parts of the spectrum, as well as in visible light.
Auroral displays occur in the outer stretches of the Earth's atmosphere, specifically in a region called the ionosphere, which runs from about 60 to 600 miles (96 to 960 km) above the Earth's surface. At these heights, air molecules are so far apart that space is practically empty like a vacuum, or the inside of a fluorescent tube.
Whenever the sun experiences a significant flare, great streams of charged particles — protons and electrons — stream toward Earth at terrific speeds; when they hit Earth's atmosphere, they clash with the molecules and atoms of the rarefied gases of the upper atmosphere. These atoms are temporarily stripped of some of their electrons by these collisions and absorb energy in the process. Such charged atoms are called ions. Within a millionth of a second the atoms regain their lost electrons and re-emit this energy in the form of light of various colors.
The electrons that are lost fly around as negatively charged particles. All the extra ions and electrons swirling arund in the atmosphere are responsible for the shortwave and CB skip changes that clue us in to the impending auroral displays.
Northern and southern lights
Actually there is always an overload of electrified particles being sent to Earth, but after taking about 20 to 30 hours to traverse the 93 million miles (150 million kilometers) between the Sun and the Earth, they have become very much affected by Earth's magnetic field. Instead of penetrating any part of the atmosphere, they flow toward the regions of the north and south magnetic poles where the night sky glows eternally with solar overcharge. The aurora at the northern magnetic pole is called aurora borealis, while the ones at the southern pole are called aurora australis (or "southern lights").
Auroras can manifest in many different types of displays: Arcs of light can extend for hundreds of miles or kilometers and start at the horizon and spread upward; long, thin streamers and rays extend toward the zenith and form curtains of light.
Green is the most commonly seen color during major displays; it is caused by the ionization of atomic oxygen. The red colors also often seen are caused by the ionization of molecular oxygen and nitrogen.
Auroral displays appear to be most frequent at the time of greatest sunspot activity. We are now seeing a slow rise toward a peak in sunspot activity which is now expected sometime around the year 2013.
Colliding Galaxies Shown In New Photo
From Space.com:
Colliding Galaxies Swirl in Dazzling New Photo
By SPACE.com Staff
posted: 05 August 2010
06:01 pm ET
A spectacular new image of two colliding galaxies shows a cosmic region teeming with stellar activity.
The cosmic smash-up, which began more than 100 million years ago but is still occurring, has triggered the formation of millions of stars in the clouds of dust and gas within the galaxies. The composite image was created using data from several different space telescopes. [Photo of the galactic spectacle.]
The most massive of these young stars speed through their evolution in only a few million years, dying a violent stellar death in supernova explosions.
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www.NexTag.com/Milky-Way-Galaxy-MapThe colliding Antennae galaxies are located about 62 million light-years away from Earth. In addition to the photo, NASA also released a video of the galaxy collision using the same data from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold), and the Spitzer Space Telescope (red).
The X-ray image from Chandra shows vast clouds of hot, interstellar gas that are injected with rich deposits of elements, such as oxygen, iron, magnesium and silicon, created in supernova explosions. The enriched gas will be incorporated into new generations of young stars and planets.
The Antennae galaxies get their name from the long, wispy antenna-like "arms" that can be detected in wide-angle views of the system. These appendage features were produced by tidal forces that were generated from the cosmic collision.
The bright, point-like sources in the image are produced by material that is falling onto black holes and neutron stars, which are dead relics of massive stars. Some of the black holes in the Antennae galaxies may contain masses that are almost one hundred times that of the sun.
The data from the Spitzer telescope show infrared light from warm clouds of dust that have been heated by newly-formed stars, with the brightest clouds lying in the overlap region between the two colliding galaxies.
The Hubble data reveal old stars and star-forming regions in gold and white, while dusty filaments appear in brown. In the optical image, many of the fainter objects denote clusters containing thousands of stars.
The Chandra image was taken in Dec. 1999, the Spitzer image was taken in Dec. 2003, and the Hubble image was taken in July 2004 and Feb. 2005. Data from the three observatories were combined to make the new composite image, which was released Thursday.
Colliding Galaxies Swirl in Dazzling New Photo
By SPACE.com Staff
posted: 05 August 2010
06:01 pm ET
A spectacular new image of two colliding galaxies shows a cosmic region teeming with stellar activity.
The cosmic smash-up, which began more than 100 million years ago but is still occurring, has triggered the formation of millions of stars in the clouds of dust and gas within the galaxies. The composite image was created using data from several different space telescopes. [Photo of the galactic spectacle.]
The most massive of these young stars speed through their evolution in only a few million years, dying a violent stellar death in supernova explosions.
Ads by GoogleFree Space WallpapersGet Cool Space Desktop Wallpapers w Planets, Moons & Stars-Try Them Now
wallpapers.smileycentral.comMilky Way Galaxy MapFind Great Deals on Milky Way Galaxy Maps. Great Maps for Less!
www.NexTag.com/Milky-Way-Galaxy-MapThe colliding Antennae galaxies are located about 62 million light-years away from Earth. In addition to the photo, NASA also released a video of the galaxy collision using the same data from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold), and the Spitzer Space Telescope (red).
The X-ray image from Chandra shows vast clouds of hot, interstellar gas that are injected with rich deposits of elements, such as oxygen, iron, magnesium and silicon, created in supernova explosions. The enriched gas will be incorporated into new generations of young stars and planets.
The Antennae galaxies get their name from the long, wispy antenna-like "arms" that can be detected in wide-angle views of the system. These appendage features were produced by tidal forces that were generated from the cosmic collision.
The bright, point-like sources in the image are produced by material that is falling onto black holes and neutron stars, which are dead relics of massive stars. Some of the black holes in the Antennae galaxies may contain masses that are almost one hundred times that of the sun.
The data from the Spitzer telescope show infrared light from warm clouds of dust that have been heated by newly-formed stars, with the brightest clouds lying in the overlap region between the two colliding galaxies.
The Hubble data reveal old stars and star-forming regions in gold and white, while dusty filaments appear in brown. In the optical image, many of the fainter objects denote clusters containing thousands of stars.
The Chandra image was taken in Dec. 1999, the Spitzer image was taken in Dec. 2003, and the Hubble image was taken in July 2004 and Feb. 2005. Data from the three observatories were combined to make the new composite image, which was released Thursday.
Tuesday, August 3, 2010
Neil Armstrong. Eighty This Week. An Appreciation
from The American Thinker:
August 03, 2010
Neil Armstrong, Eighty This Week. An Appreciation
Andrew Sumereau
For over half of his life now, Neil Armstrong has gracefully enjoyed and endured the appellation "First Man on the Moon." And, although his popularity is currently way below the likes of Lady Gaga (whoever that is), it can be reasonably argued that over the next millennia, when the history of the Twentieth Century is written, his name will stand out over all others. When the Obamas, Stalins, and Churchills have gone the way of just so many Caesars and Pharaohs of old, when the great movements and wars are forgotten, Neil Armstrong's name will live on, not for who he was, but for what he did. And, as with so many of the great, his attributes will probably be appreciated far more after he is gone.
A son of an Ohio state government worker, Armstrong enjoyed a comfortable small-town Depression upbringing distinguished only by an unusual passion for flight. He took to flying at a young age, earning his pilot's license at sixteen, he joined the Navy, and flew Panther jets from aircraft carriers by the time he was twenty. A member of the famous "Screaming Eagles" all-jet Fighter Squadron 51, he flew hazardous combat missions over North Korea and China. Armstrong was one of the few to make over 100 carrier landings, his squadron's exploits were later dramatized in the William Holden feature "The Bridges Over Toko-Ri."
Returning to Purdue University after Korea to finish his degree in aeronautical engineering in 1955, civilian Armstrong was recruited to pilot and test the newly developed experimental rockets and jets at Edwards Air Base in California. Contemporary of the celebrated and colorful Chuck Yeager, test pilot Armstrong set records for speed and altitude with a quiet workman-like demeanor that was to characterize his entire professional life. Brushing the edge of space at 207,500 feet in the X-15 hypersonic aircraft, Armstrong tested the limits of aerodynamics miles above the western desert just as Sputnik was rocking the scientific (and political) world.
Assigned to the now largely forgotten Dyna-Soar project, which developed airplane-like space vehicles and competed with early NASA rocketry like that used in Project Mercury, Armstrong remained active and busy as "pilot-engineer" while the space race heated up. To the surprise of many of his friends and co-workers, he applied for the second group of openings for NASA's growing astronaut corps in 1962, after Kennedy's call for a moon landing "before the decade was out." Selected as the very first civilian astronaut, he trained with the extraordinary group of nine men who joined the legendary "Right Stuff" Original Seven astronauts; men of the highest caliber, (names every schoolchild should know, but alas, does not,) -intelligent, educated, fearless, and destined for challenges of the highest order, triumphs, disasters and death: Lovell, White, Borman, Conrad, Young, See, Stafford, and McDivitt.
Named commander of Gemini VIII, Armstrong gained repute for his coolness under pressure when his malfunctioning capsule began turning end-over-end at a sickeningly and dangerously fast rate after the first successful docking of spacecraft in orbit. Aborting the mission after bringing the spacecraft to safety, a depressed Armstrong dismissed any hint that his actions were heroic, regretting the missed opportunities, focused as he was on the mission and the consequences to Project Gemini and its follow-up, Project Apollo.
Of the moon mission, and the drama over landing at Tranquility Base, as Buzz Aldrin coolly counted down the fuel readings while Armstrong piloted the Lunar Module over boulders and craters, more is known. The entire world watched as history unfolded that July night in 1969; the dramatic landing, the other-worldly television show, the snowy black and white picture revealing two Americans bouncing along the lunar surface and speaking to Nixon via telephone. The nation, the world, was thrilled and inspired, and then, as always, moved on to the ephemeral and mundane, and, ultimately, forgot.
After the ticker-tape parades and banquets and public honors across the globe, Armstrong moved on to what many consider the most exemplary part of his life. For the unique contribution of the first man on the moon may not lie in his courage or his resourcefulness or his patriotism, but rather in his bearing and dignity over forty plus years of exposure and fame.
In 1971, after retiring from NASA, Armstrong began teaching Aerospace Engineering at the University of Cincinnati. He avoided offers from many businesses to act as spokesman until Chrysler, in financial difficulties and backed by a loan from the federal government, successfully approached him to advertise its renewed commitment to automotive engineering excellence. Subsequently, he quietly served on the boards of several companies, and was asked to serve on the Rogers Commission investigating the Challenger Shuttle disaster in 1986. Much of his time has been spent avoiding the spotlight and preserving his name, image and reputation.
In his private life he has known great happiness and great struggle. Losing his two-year old daughter to a rare brain cancer in 1961, and divorcing his wife after 38 years of marriage, the trials of his profession have left scars. "Most of my adult life," he said, "has been spent saying goodbye to friends and colleagues." He suffered a heart attack in 1991 and recovered to find a new bride in 1994. "Retired" in 2002, Armstrong celebrates his 80th birthday today.
Perhaps the modern world, and especially modern America, enjoys creating celebrities and heroes out of nothing almost as much as tearing them down. A man like Neil Armstrong, a hero of deeds and courage and character, stands out as a rarity to say the least. How lucky we are that the person chosen by fate to be the first to walk on the moon was such a man.
Posted at 03:04 PM
August 03, 2010
Neil Armstrong, Eighty This Week. An Appreciation
Andrew Sumereau
For over half of his life now, Neil Armstrong has gracefully enjoyed and endured the appellation "First Man on the Moon." And, although his popularity is currently way below the likes of Lady Gaga (whoever that is), it can be reasonably argued that over the next millennia, when the history of the Twentieth Century is written, his name will stand out over all others. When the Obamas, Stalins, and Churchills have gone the way of just so many Caesars and Pharaohs of old, when the great movements and wars are forgotten, Neil Armstrong's name will live on, not for who he was, but for what he did. And, as with so many of the great, his attributes will probably be appreciated far more after he is gone.
A son of an Ohio state government worker, Armstrong enjoyed a comfortable small-town Depression upbringing distinguished only by an unusual passion for flight. He took to flying at a young age, earning his pilot's license at sixteen, he joined the Navy, and flew Panther jets from aircraft carriers by the time he was twenty. A member of the famous "Screaming Eagles" all-jet Fighter Squadron 51, he flew hazardous combat missions over North Korea and China. Armstrong was one of the few to make over 100 carrier landings, his squadron's exploits were later dramatized in the William Holden feature "The Bridges Over Toko-Ri."
Returning to Purdue University after Korea to finish his degree in aeronautical engineering in 1955, civilian Armstrong was recruited to pilot and test the newly developed experimental rockets and jets at Edwards Air Base in California. Contemporary of the celebrated and colorful Chuck Yeager, test pilot Armstrong set records for speed and altitude with a quiet workman-like demeanor that was to characterize his entire professional life. Brushing the edge of space at 207,500 feet in the X-15 hypersonic aircraft, Armstrong tested the limits of aerodynamics miles above the western desert just as Sputnik was rocking the scientific (and political) world.
Assigned to the now largely forgotten Dyna-Soar project, which developed airplane-like space vehicles and competed with early NASA rocketry like that used in Project Mercury, Armstrong remained active and busy as "pilot-engineer" while the space race heated up. To the surprise of many of his friends and co-workers, he applied for the second group of openings for NASA's growing astronaut corps in 1962, after Kennedy's call for a moon landing "before the decade was out." Selected as the very first civilian astronaut, he trained with the extraordinary group of nine men who joined the legendary "Right Stuff" Original Seven astronauts; men of the highest caliber, (names every schoolchild should know, but alas, does not,) -intelligent, educated, fearless, and destined for challenges of the highest order, triumphs, disasters and death: Lovell, White, Borman, Conrad, Young, See, Stafford, and McDivitt.
Named commander of Gemini VIII, Armstrong gained repute for his coolness under pressure when his malfunctioning capsule began turning end-over-end at a sickeningly and dangerously fast rate after the first successful docking of spacecraft in orbit. Aborting the mission after bringing the spacecraft to safety, a depressed Armstrong dismissed any hint that his actions were heroic, regretting the missed opportunities, focused as he was on the mission and the consequences to Project Gemini and its follow-up, Project Apollo.
Of the moon mission, and the drama over landing at Tranquility Base, as Buzz Aldrin coolly counted down the fuel readings while Armstrong piloted the Lunar Module over boulders and craters, more is known. The entire world watched as history unfolded that July night in 1969; the dramatic landing, the other-worldly television show, the snowy black and white picture revealing two Americans bouncing along the lunar surface and speaking to Nixon via telephone. The nation, the world, was thrilled and inspired, and then, as always, moved on to the ephemeral and mundane, and, ultimately, forgot.
After the ticker-tape parades and banquets and public honors across the globe, Armstrong moved on to what many consider the most exemplary part of his life. For the unique contribution of the first man on the moon may not lie in his courage or his resourcefulness or his patriotism, but rather in his bearing and dignity over forty plus years of exposure and fame.
In 1971, after retiring from NASA, Armstrong began teaching Aerospace Engineering at the University of Cincinnati. He avoided offers from many businesses to act as spokesman until Chrysler, in financial difficulties and backed by a loan from the federal government, successfully approached him to advertise its renewed commitment to automotive engineering excellence. Subsequently, he quietly served on the boards of several companies, and was asked to serve on the Rogers Commission investigating the Challenger Shuttle disaster in 1986. Much of his time has been spent avoiding the spotlight and preserving his name, image and reputation.
In his private life he has known great happiness and great struggle. Losing his two-year old daughter to a rare brain cancer in 1961, and divorcing his wife after 38 years of marriage, the trials of his profession have left scars. "Most of my adult life," he said, "has been spent saying goodbye to friends and colleagues." He suffered a heart attack in 1991 and recovered to find a new bride in 1994. "Retired" in 2002, Armstrong celebrates his 80th birthday today.
Perhaps the modern world, and especially modern America, enjoys creating celebrities and heroes out of nothing almost as much as tearing them down. A man like Neil Armstrong, a hero of deeds and courage and character, stands out as a rarity to say the least. How lucky we are that the person chosen by fate to be the first to walk on the moon was such a man.
Posted at 03:04 PM
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