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In 1539, the German mathematician Georg Joachim Rheticus appeared at the town of Frauenburg, now Frombork on the Baltic coast in northern Poland, to seek a meeting with a Catholic clergyman in his late sixties. A few months earlier, Rheticus heard rumours that this obscure Polish cleric had formulated a revolutionary new theory concerning the relationship between the Sun, the Earth, and the other planetary bodies. At this time, the whole of Europe believed that the Earth was fixed at the centre of the Universe. For decades, Nicolaus Copernicus had been making
astronomical observations to develop his own heliocentric model. However, the Polish cleric was unwilling to publish his work, preferring to make his theories known to a small group of acquaintances who could understand the complex mathematics behind them. After meeting Copernicus, Rheticus persuaded him to publish his treatise De revolutionibus orbium coelestium, or On the Revolutions of the Heavenly Spheres, and spent two years working with him to revise the text before returning to Germany to arrange its publication. Copernicus anticipated that the publication of his
treatise would launch an astronomical revolution, but he would not live to see its impact, dying on 24 May 1543 shortly after receiving the final copy of his published work. This is the story of Nicolaus Copernicus, the Polish clergyman who turned the universe inside out. The man known to history as Nicolaus Copernicus was born on 19 February 1473 in the city of Toruń on the banks of the Vistula River. The Polish city was then part of Royal Prussia, an autonomous
German-speaking region under the Polish Crown. Nicolaus Copernicus is the Latinized version of his birth name Niklas Koppernigk, and in Poland he is known as Mikołaj Kopernik. His father Niklas Koppernigk the Elder was a wealthy copper merchant whose family came from the village of Koperniki in Upper Silesia, close to the modern-day border of Poland and Czechia. By the 1380s, the family had moved to Krakow, then the capital of the kingdom of Poland. By the late 1450s, Nikolas Koppernigk the Elder had moved to Toruń, an important trading centre over 200 miles downstream from Krakow. Within a few years of his arrival at Toruń,
Niklas married Barbara Watzenrode, the daughter of one of the city's richest and most influential men. The couple lived in a tall redbrick house on what is now Copernicus Street and had two sons and two daughters, all of whom survived into adulthood. The future astronomer was the youngest of the four children. Copernicus lived during the European Renaissance, an age of intellectual curiosity inspired by classical antiquity and accompanied by a sceptical attitude towards Christian understandings of the world. While the Renaissance is perhaps most closely associated
with artistic masterpieces of Leonardo, Raphael, and Michelangelo in Italy, the Renaissance was a pan-European phenomenon that also took root in Copernicus's native Poland. The kingdom of Poland and the Grand Duchy of Lithuania had been in dynastic union under the Jagiellonian Dynasty since 1385 and was one of the largest states in Europe. At the time of Copernicus's birth, both parts of the union were ruled by Casimir IV, one the most successful kings in Polish history. While Copernicus was born in Toruń, his family was well connected to the capital of Krakow. Young
Niklas was around ten years old when his namesake father died in 1483. The Koppernigk children may have been orphans at this point, since there is no record of the date of their mother's death. Their uncle Lukas Watzenrode, a canon in the diocese of Warmia, assumed responsibility for their upbringing. Copernicus attended school at Toruń and later Włocławek with financial support from uncle Lukas, who was elected Prince-Bishop of Warmia in 1489. Two years later, the 18-year-old Copernicus and his elder brother Andreas began their studies at the Jagiellonian University
in Krakow. The course of study included logic, poetry, rhetoric, and natural philosophy, but Copernicus was attracted above all to astronomy and mathematics, which was a particular strength of the University of Krakow. He combined his university studies with independent reading and began collecting a library of astronomical books. After four years at the Jagellonian University, Copernicus left Krakow without taking a degree and joined his uncle in Warmia. The Prince-Bishop had arranged for the election of his young nephew as one of the sixteen canons of the Frauenburg
Chapter in Warmia, though Copernicus was not confirmed until 1497 while studying at the University of Bologna in Italy. In September 1496, Copernicus began his studies in canon law at the oldest university in Europe, where he lodged with the astronomy professor Domenico Maria Novara, who helped him make his first observation in March 1497. After four years in Bologna, Copernicus visited Rome for the jubilee year celebrations in 1500. He was still in the Eternal City on 6 November, where he observed a partial lunar eclipse. While Copernicus lectured in
mathematics, he remained destined for a career in the Church. Nicolaus and his brother Andreas were back in Warmia in 1501 but obtained permission to return to Italy to pursue further studies at the University of Padua, where Nicolaus studied medicine to become a church physician. However, he curtailed his studies after two years and instead obtained a doctorate in canon law from Ferrara in May 1503. The 30-year-old Copernicus returned to Warmia, where he remained for the rest of his life. Although the cathedral of Warmia was in Frauenburg on the Vistula,
Bishop Watzenrode lived 50 miles away at the bishop's palace in Heilsberg, present-day Lidzbark Warminski. While serving as his uncle's physician and secretary at the episcopal palace, Copernicus treated the local population for free and was known as Doctor Niklas. He had steady incomes as a canon alongside an additional sinecure from the Church of the Holy Cross in Wrocław. Copernicus continued his astronomical observations at Heilsberg and began teaching himself Greek in order to study the works of the ancient Greek astronomers.
The official systems of astronomy were based on the writings of the Greek philosopher Aristotle in the 4th century BC and the astronomer Claudius Pompey in Roman Egypt in the 2nd century AD. Although the Greek astronomer Aristarchus of Samos had proposed an alternative model in which the planets orbited the Sun as early as the 2nd century BC, geocentricism remained the officially accepted view and was endorsed by the Christian Church. As part of his efforts, Copernicus translated a collection of 85 letters by Byzantine historian Theophylactus Simocatta
from Greek into Latin, which was published in Krakow in 1509. Although the prince-bishop was cultivating his nephew as his successor, in 1510 the 37-year-old Copernicus left his uncle's employ and moved to Frauenburg to carry out his functions as canon in person. On 29 March 1512, Lukas Watzenrode died in his native Toruń while returning from the wedding of King Sigismund I in Krakow. At Frauenburg, Copernicus befriended his fellow canon Tiedemann Giese, who also had an interest in astronomy. Copernicus' biographer Dava Sobel suggests that Giese was the first to hear
of Copernicus's new theory in around 1510. The amateur astronomer had written a brief summary of his theory, in which he praised Ptolemy's accomplishments but highlighted some inadequacies in Ptolemy's efforts to explain the apparent backward motion of planets in the sky with eccentric orbits, which contradicted the Aristotelian view that the movements of the planets were regular. Although familiar with some of Aristarchus's work, Copernicus does not appear to have known about his heliocentric model. Copernicus suggested that the inconsistencies
in the Ptolemaic system would be resolved if all planets were to orbit the Sun rather than the Earth, which was a planet like the others and rotated on its axis once a day. With this perspective, Copernicus easily ordered the known planets out from the Sun as Mercury, Venus, Earth, Mars, Jupiter, and Saturn. The only celestial object which orbited the Earth was the Moon. Copernicus left out the mathematical proof behind the theory and announced his intention to publish a more comprehensive book with all the calculations. This essay, later known as the
Commentariolus or Brief Sketch, was initially circulated among a small group of friends, but was subsequently copied and became known to the wider European scientific community, which eagerly awaited the publication of the proof. Copernicus was sidetracked by his ecclesiastical duties, especially following the death of his uncle and the election of his colleague Fabian Luzjanski as the new bishop. Meanwhile, as his brother Andreas developed leprosy and left for Italy, where he lingered until his death in 1518, Copernicus assumed additional responsibilities for managing church properties and in 1514 he
moved into a house outside the cathedral complex, where he built a level patio for his astronomical observations. He also used a tower in the cathedral's perimeter wall to observe the heavens. In 1515, he was consulted as part of Pope Leo X's attempt to reform the Julian Calendar, but his comments have not survived. In 1517, Copernicus left Frauenburg for Allenstein or Olsztyn at the southern extremity of the diocese of Warmia to manage the church's properties. Copernicus kept administrative records, responded to petitions from peasants,
and arbitrated over land disputes. In between, he continued his astronomical work and painted a sundial on the wall of his apartment at Allenstein Castle to take observations of the Sun and calculate the length of a year by measuring the time between equinoxes. He repeated the experiment each passing year and arrived at an answer within minutes and seconds of the true figure. On more earthly matters, Copernicus applied his mathematical abilities to prove that unscrupulous Polish merchants were debasing coinage. In August 1517, he completed the Meditata, a brief essay
about the corruption, which he translated into German for the authorities in Danzig in 1519. While Copernicus was exposing the corruption of the merchant class, the German theologian Martin Luther began circulating his criticisms of the Catholic Church. Luther would soon unleash the Protestant Reformation, but Copernicus's revolution was still two decades away. Copernicus left Allenstein in December 1519 at the end of his term, but a few weeks after returning to Frauenburg the town was attacked by the Teutonic Knights, the Germanic Crusader order which established its own state in the Baltics after defeating the last
pagans in Europe. The Poles were no match for the energetic Albrecht of Hohenzollern, the Grand Master of the Teutonic Order, and Copernicus was obliged to beat a hasty retreat back to the former Teutonic fortress at Allenstein, which soon fell under siege. During this anxious period, Copernicus organised the castle's defences, appealed to Krakow for reinforcements to lift the siege and liberate Warmia, catalogued the chapter's archives, and continued his planetary observations at night. After the arrival of Polish reinforcements in late 1520,
the Teutonic knights lifted the siege, and a truce was signed in April. Copernicus was recalled to Frauenburg in June, although the Teutonic knights continued to raid Polish territory. In March 1522, Copernicus deputised for Bishop Fuzjanski at negotiations with the Teutonic knights at Graudenz. A few days later, he spoke on the devaluation of coinage and proposed a new monetary standard issued by a single authority to replace the existing system that used both Polish and Prussian coinage. Meanwhile, Albrecht von Hohenzollern went to Wittenberg to meet
the excommunicated Martin Luther, who began to encourage him to break from the Catholic Church. Albrecht's rival Bishop Fuzjanski died in January 1523, and Copernicus was ordered to Heilsberg to manage the bishopric of Warmia until the confirmation of King Sigismund's appointee, Maurycy Ferber. In the early hours of 26 August, Copernicus observed a lunar eclipse that enabled him to record the positions of the Sun and Moon with great accuracy. In October 1523, after Ferber was installed on the episcopal throne, Copernicus was glad to
return to Frauenburg. He was now in his early fifties and keen to continue his astronomical work before his eyesight failed him. In June 1524, he wrote a paper addressed to his friend Bernard Wapowski entitled Letter Against Werner. Copernicus was responding to Johannes Werner's 1522 publication The Motion of the Eighth Sphere, which argued that the stars of the night sky were firmly embedded in an eighth sphere that slowly rotated in the opposite direction to the planets. Copernicus highlighted several errors in Werner's calculations, but instead of presenting his own
solution he informed Wapowski that he would "set forth my views elsewhere." Few people would have paid attention to Copernicus's private letter at a time when Luther's challenge to Rome not only split the Western Church but fuelled a peasant rebellion that Luther repudiated. While the bishop of Warmia remained affiliated to Rome, neighbouring dioceses adopted Lutheranism, as did Albrecht of Hohenzollern, who dissolved the Teutonic Order and re-established himself as Duke of Prussia and a vassal of the Catholic King Sigismund of Poland. Copernicus and his
friend Tiedemann Giese were moderates, but were compelled to vote in favour of Ferber's decision to expel the Lutherans from Warmia. Despite his distinguished record of service at Frauenburg Chapter, in February 1531 Copernicus received a stern letter from Bishop Ferber threatening to dismiss him as canon unless he was ordained as a priest. In July, Ferber issued a further reprimand after receiving intelligence that Copernicus's former housekeeper Anna Schilling had stayed at his house after separating from her husband. Copernicus pleaded his innocence and continued
to carry out his administrative duties as the officer responsible for the Chapter's finances. He proposed a system for changing the weight of bread in response to fluctuating wheat prices to keep bread affordable while protecting the Chapter's financial interests. Copernicus's unorthodox views about the Sun and the Earth may have made him vulnerable to charges of heresy, and even though his manuscript was essentially completed by the early 1530s, he was hesitant to arrange its publication. In 1535, his friend Bernard Wapowski sought to arrange publication of an almanac compiled by Copernicus in Vienna, but died a few weeks
later. In summer 1533, the papal secretary Johann Widmanstetter explained Copernicus's theory to Pope Clement VII, who expressed his favour. After Clement's death, Widmanstetter worked for Cardinal Nicholas Schönberg, who wrote to Copernicus in November 1536 seeking a copy of his manuscript. Copernicus received the letter without responding, since he was still unable to prove parts of his theory and feared being ridiculed by publishing an incomplete proof. He was also busy with his official responsibilities, making frequent trips to Heilsberg to attend to Bishop
Ferber. After Ferber's death in early summer 1537, Copernicus once again assumed responsibility for the bishopric's affairs during the interregnum. After the election of Johannes Dantsicus, as the new bishop of Warmia, Copernicus's friend Giese succeeded Dantsicus as bishop of the smaller diocese of Kulm. The relationship between the new bishop and the canons of the Frauenburg Chapter was fraught after Dantsicus had spent over a decade seeking office in Warmia before obtaining his canonry in 1529. Although Dantsicus had been a notorious womaniser and
had flirted with the cause of Lutheran reform earlier in life, as bishop of Warmia he was a Catholic zealot determined to crack down on church officials living in sin. Copernicus's relationship with his housekeeper attracted renewed scrutiny, but he refused to give her up despite informing the bishop he would do so. Amidst Dantsicus's anti-Lutheran zealotry, the 25-year-old Rheticus arrived in Frauenburg seeking Canon Copernicus. Rheticus was not only a Lutheran, but he was a professor of mathematics at Luther's Wittenberg University. He was 22
years old in 1536 when he was appointed to the professorship by Philip Melanchthon, Luther's close collaborator. Melanchthon and Rheticus shared an interest in astrology and believed that a better understanding of the heavens was key to achieving a better understanding of God. In September 1538, Melanchthon sent Rheticus to study with Europe's leading scholars. Rheticus's first port of call was Nuremberg, where he called on Johann Schöner, the headmaster of a secondary school and one of the city's leading intellectuals. Schöner was the heir of a tradition
founded by the German astronomer Johannes Müller, better known as Regiomontanus, who was known for a treatise on trigonometry and for his work on translating the Almagest, Ptolemy's astronomical treatise, from Greek to Latin. Schöner himself was an accomplished polymath who published astronomical texts and a series of globes that were among the first to show the New World, which he named America after Amerigo Vespucci. Schöner or someone in his circle would have been acquainted with Copernicus's Commentariolus that sketched out his heliocentric theory without
going into any detail. After spending several months in Nuremberg studying with Schöner and his colleagues, Rheticus resolved to travel to Poland with the cartographer Heinrich Zell to seek out Copernicus himself. In May 1539, they arrived in Frauenburg, with its vast cathedral towering over a modest little town. Despite the risk of imprisonment as a Lutheran, Rheticus bravely knocked on the door of Copernicus's house and introduced himself to one of his servants as a mathematician. While Copernicus the canon would undoubtedly have been hesitant about welcoming
the young stranger, Copernicus the astronomer was immediately intrigued by the three bound volumes that his visitor presented to him as gifts. It had only been a century since Johannes Gutenberg invented the movable type printing press, and books remained valuable commodities. The books that Rheticus brought with him included a copy of Euclid's Elements in the original Greek, Regiomontanus's trigonometry treatise On Triangles of Every Kind, and most important of all, the Greek edition of Ptolemy's Almagest, which had only been published in 1538. Copernicus would have
been thrilled with these valuable gifts, and with the very fact that Rheticus was not only aware of his work, but had travelled hundreds of miles into enemy territory to consult him about it. Copernicus took him on a tour of his hometown and showed him his observatory, where he had to make do with three relatively rudimentary instruments: a triquetrum for determining the altitude of celestial bodies using trigonometry, a quadrant to record summer and winter solstices, and a spherical astrolabe to determine the position of the heavenly bodies in the night sky. Copernicus
soon showed Rheticus the holy grail that he was seeking, the unpublished manuscript of his proof for heliocentrism. Rheticus spent the next four months poring over the hundreds of pages of tables, diagrams, equations, and explanatory text and was suitably impressed by Copernicus's genius, which he compared to that of Ptolemy. Rheticus described the way in which Copernicus combined the data from his own observations with those by astronomers through the ages. He used the raw data to form his own hypotheses, which he compared with those of Ptolemy and other ancient astronomers.
Rheticus was particularly impressed by Copernicus's systemic approach to the problems with the Ptolemaic system in contrast to other astronomers, who satisfied themselves with developing theories to explain minor discrepancies in their observations as well as Ptolemy's model of the universe. Copernicus's efforts to understand the motions of the universe from first principles led Rheticus to equate him with Ptolemy. Like Ptolemy's Almagest, Copernicus divided his manuscript into six parts. The first was a general description of the heliocentric system, the second discussed his theory of the fixed stars,
and how they appeared to move gradually in reverse across the night sky. The third and fourth books were about the Sun and the Moon, and the fifth and sixth about the movements and positions of the planets. Rheticus obtained Copernicus's permission to write his own summary of the heliocentric theory, which became the Narratio prima or First Report. Both men were thrilled about their collaboration, though Rheticus reported that there were also frequent arguments between them as he expressed his frustration that Copernicus's profound ideas were punctuated by painstakingly
detailed calculations. The collaboration continued even as Copernicus and Rheticus faced scrutiny from Bishop Dantsicus. By the time of Rheticus's arrival, Copernicus may have already asked Anna Schilling to move out of his house, but reports continued to reach the bishop that she continued to visit the house. The bishop's spies would have known about the arrival of the young stranger and sought to establish his identity. It is unclear how Copernicus obtained a dispensation to allow Rheticus to remain in Frauenburg, or whether he informed the bishop of his student's affiliation
with Wittenberg. While the Bishop of Warmia was suspicious of Rheticus's activities, Tiedemann Giese was eager to make the acquaintance of the German mathematician and invited Copernicus and Rheticus to meet him at the bishop's castle in Löbau, present-day Lubawa. Shortly before their arrival in early July, Giese received a letter from Dantsicus urging him to convey his displeasure at Copernicus's continued dealings with Anna Schilling. Copernicus signalled his willingness to comply, while Giese, Rheticus, and Copernicus discussed the prospects of publishing the full manuscript of his work.
According to Rheticus, Giese had encouraged Copernicus to continue working on his astronomical theory to further the cause of calendar reform and to ensure that Christian festivals were being observed on the appropriate day. Rheticus claimed that Copernicus was only prepared to publish his astronomical tables, which would avoid causing any controversy while providing accomplished mathematicians with the necessary information to infer his heliocentric theory. Copernicus argued that by doing so he was following in the footsteps of the ancient mathematician Pythagoras,
whose fame continued to echo through the ages even though he only circulated his work among a small group of scholars. Giese disagreed and believed that Copernicus should publish his whole proof and be prepared to defend it from critics. Although Rheticus credited Giese for persuading Copernicus to publish, it was in fact his own efforts that finally encouraged the aging canon to present his work to the world. Copernicus and Rheticus returned to Frauenburg in late summer, and on 23 September 1539 Rheticus completed his summary of Copernicus's theory. Rheticus
and Zell went to Danzig, present-day Gdansk, and delivered the manuscript to Franciscus Rhodes, who published the short book in April 1540. Rheticus's Narratio Prima took the form of a long letter of some 100 pages addressed to Johann Schöner. While Copernicus's name appeared on the title page, throughout the text Rheticus simply referred to him as his teacher. Rheticus crafted his own narrative based on his study of Copernicus's work, placing him in the tradition of the great astronomers before him. Rather than shock the world by introducing heliocentrism right away,
Rheticus begins by discussing the apparent motions of stars and the shortcomings of the received wisdom. Around 20 pages in, following an astrological digression and a prediction of the Second Coming of Christ, Rheticus concludes that the Ptolemaic system cannot explain the movements of the heavenly bodies and offers Copernicus's heliocentric theory as an alternative. The idea that the Earth orbits the Sun is not the only revolutionary aspect of Copernicus's theory. The concept that the Earth completes a full rotation every day would have seemed even more incredible.
Following its publication, Rheticus dispatched copies of the Narratio to his acquaintances in Nuremberg, thus confirming Copernicus's reputation in Schöner's circle. In August 1540, the Nuremberg publisher Johannes Petreius wrote to Rheticus urging him to convince Copernicus to publish his manuscript with him. The letters from Petreius and others had their desired effect, and from summer 1540 Copernicus spent the following year making revisions to prepare the manuscript for publication. He made substantive changes to his section on trigonometry with the aid of Regiomontanus's On Triangles of Every Kind that Rheticus had gifted
him. Since Copernicus did most of the revisions himself, Rheticus and his friend Heinrich Zell occupied themselves by surveying the surrounding countryside to complete a detailed map of Prussia that Copernicus had started many years earlier. In the winter of 1540-1541, Rheticus briefly returned to Wittenberg to give two lectures in astronomy. After his return to Frauenburg, in April 1541 Rheticus accompanied Copernicus to the Prussian capital of Königsberg, where the canon was summoned to attend to the illness of one of Duke Albrecht's advisers. Despite the previous
animosity between the Poles and the Teutonic knights, after his conversion to Lutheranism and the secularisation of the Prussian state, Albrecht recognised that he owed his status to his liege, the king of Poland. In his efforts to obtain protection for the Lutheran Rheticus, Tiedemann Giese had dispatched a copy of the Narratio to Albrecht in May 1540. Some twenty years after facing down Albrecht's knights from the walls of Allenstein Castle, Copernicus and Albrecht now had an opportunity to discuss the scientific and religious implications of his theory.
Upon their return from Frauenburg in May 1541, Copernicus and Rheticus each received letters from Andreas Osiander of Nuremberg, a theologian and mathematician in Schöner's circle, advising them how to publish the manuscript without offending the sensibilities of religious and academic establishments. Osiander suggested that Copernicus should present his system as the result of computations that offered a convenient means of describing the motions of the planets without necessarily being a representation of reality. He advised Rheticus to offer up the possibility
for someone to develop competing hypotheses that may be equally valid. Meanwhile, Achilles Gasser, an astrologer who lived in Rheticus's hometown of Feldkirch in western Austria, published a second edition of the Narratio prima in Basel. He acknowledged that Copernicus's theory might be considered heretical but represented "the rebirth of a true system of astronomy," and urged its progenitor to publish his proof. Whatever reservations Bishop Dantsicus may have had about both Copernicus and Rheticus, he was an acclaimed poet who had intellectual curiosity
about Copernicus's work. He received letters from scholars as far away as the Netherlands urging him to take a close interest in the publication of Copernicus's manuscript, which would make his bishopric of Warmia the intellectual centre of the world. By June 1541, he wrote to Copernicus offering his official backing for publication and agreed to provide a few verses for the preface. By late summer 1541, Copernicus had finished all the necessary revisions to his manuscript, which is now in the collection of the University of Krakow. Rheticus had made a fair copy which he would
deliver to the printer, and in late September he and Zell bade Copernicus their final farewell and embarked on their journey back to Wittenberg. While Rheticus had raised his profile among the European intellectual community as Copernicus's collaborator, he returned to Wittenberg to a mixed reception. He may have had a sense of this while delivering his lectures over the previous winter, since he had obtained a letter of recommendation from Duke Albrecht to the Elector of Saxony urging Rheticus to be confirmed in his professorship. While Rheticus was in fact
promoted to dean of the Faculty of Arts, Luther disparagingly referred to Copernicus's efforts as an attempt to "turn the whole of astronomy upside down," and Melanchthon also expressed his irritation with Copernicus's views. Meanwhile, Rheticus's new responsibilities at Wittenberg prevented him from supervising the publication of Copernicus's manuscript in Nuremberg. Instead, he extracted two sections on trigonometry from Copernicus's work for publication in Wittenberg, availing himself of the opportunity to introduce it with Bishop Dantsicus's verses that he had
originally intended to introduce the full work. After the end of the academic year in May 1542, Rheticus personally delivered the full manuscript to Petreius in Nuremberg for publication. Back in Frauenburg, Copernicus was having second thoughts in Rheticus's absence. He struggled to fit his data for the movements of the planet Mercury into his hypothesis and continued to make amendments to his manuscript. Nevertheless, Copernicus composed a letter dedicating his book to Pope Paul III, which he dispatched to Nuremberg in June 1542. Copernicus admitted to the pontiff
that his book might be ridiculed and explained that he had been pressured into publication by his friends. Copernicus explained that the Ptolemaic system with its eccentric orbits failed to offer a satisfactory representation of the perfection and order of God's creation. Having rejected the impossibility of the Ptolemaic model, Copernicus outlined his new hypothesis of a stationary Sun and a moving Earth and warned that it could only be understood by intellectuals like the Pope himself. He concluded by reminding the Pope of the urgency of reforming the
ecclesiastical calendar and invited the pontiff and his astronomers to examine his insights. The publication of Copernicus's manuscript was a laborious process that would take several months. Not only did Petreius have to arrange for the carving of bespoke woodblocks for the 142 diagrams, but it took time for the ink to dry on each page. Petreius had agreed to cover all the costs of the print run of several hundred copies. The first few sections of the text arrived in Frauenburg in June 1542 for Copernicus to review. The author was impressed by the print quality but
could not avoid identifying a few amendments he wanted Petreius to make. The publisher could not afford to reprint the pages with the changes, but added an extra page listing the errors that Copernicus had identified. Rheticus supervised the publication in the summer, but in October he left Nuremberg for Leipzig, where he had been appointed professor of higher mathematics. Upon his departure, he asked Andreas Osiander to supervise the publication. More printed pages arrived in Frauenburg for review, but Copernicus was no longer able to do so after suffering a
serious stroke in November 1542 that impaired his memory and deprived him of his ability to speak. The previous year, Copernicus had arranged for his teenage kinsman Jan Loitz of Danzig to serve as his assistant and presumed successor to his canonry. Tended by his friend and colleague Canon Jerzy Donner, Copernicus remained semi-paralysed over the winter as his condition gradually declined. Copernicus entered a coma in early May 1543 and remained asleep on 24 May when the final pages of his book were delivered to his house. This included the title page
identifying its author as "Nicolaus Copernicus of Toruń." According to legend, as Donner placed the printed sheets in its author's hands, Copernicus briefly opened his eyes before breathing his last, taking his leave from the earthly realm at the age of 70. He was subsequently buried under the cathedral without a grave marker. Over the seven decades of his life, Nicolas Copernicus of Toruń was known to most of his acquaintances through his work as a medical doctor and canon of the Frauenburg Chapter in the diocese of Warmia. Notwithstanding the salacious rumours
surrounding Copernicus and his housekeeper, the canon was held in great esteem throughout Frauenburg and beyond. The older generation would have remembered his uncle and patron, Prince-Bishop Lucas Watzenrode, one of the most distinguished men to hold the office. Having spent more than a decade studying at the universities of Krakow, Bologna, and Padua, Copernicus was well-educated, but he was not alone among his colleagues in his interest in astronomy and mathematics. Copernicus's academic training served him well as an administrator,
and he regularly held senior appointments, including the responsibility of governing the prince-bishopric while the episcopal office was vacant. His administrative talents even enabled him to successfully defend Allenstein against a siege by the Teutonic knights. Yet behind his official responsibilities, Copernicus spent years collecting astronomical data from his own observations and from others, and diligently performed calculations to trace the movements of the Sun, the Moon, the Earth, and the other planetary bodies. His theory
that the Sun was at the centre of the universe, and that the Earth not only orbited the Sun but spun around its axis, began circulating among a small group of intellectually curious friends from the early 1510s. As Copernicus continued to work on his proof, his theories reached the community of astronomers around Johann Schöner in Nuremberg, and even the heart of the Catholic Church in Rome. Although he had completed the manuscript by the 1530s, he feared ridicule and resisted the repeated pleas by his friend Tiedemann Giese to publish his proof. It was up to the young mathematician Georg Joachim Rheticus to successfully persuade
Copernicus to consent to the publication of De revolutionibus during his final years. Copernicus's friend Tiedemann Giese had advised him to be prepared to defend his theory from critics after publishing his magnum opus. Copernicus's illness and death prevented him from doing so, and it was up to Rheticus to defend his legacy in the first instance. However, Rheticus was not impressed by the first edition of De revolutionibus, which was introduced by an anonymous preface addressed to the reader, echoing Andreas Osiander's advice to present
Copernicus's work not as a definitive proof, but a plausible hypothesis of the workings of the universe. Copernicus was in no condition to object to these words, but the apologetic introduction had been Osiander's own, and Rheticus was infuriated when he saw them in print. Rheticus had crossed out the preface in the copy he sent to Giese, who was equally infuriated by the offending remarks. Rheticus was astonished to see that although Copernicus had acknowledged Giese and the late Cardinal Schönberg's efforts to encourage his publication, Rheticus's name did not appear at
all. While Dava Sobel argues that Copernicus chose not to name the Lutheran professor in a dedication addressed to the Pope, Jack Repcheck argues it would have made little difference since Rheticus's collaboration with Copernicus was known through the Narratio prima. In his reply, Giese informed Rheticus of Copernicus's demise and apologised for the absence of Rheticus's name in the dedication, which he recognised as an injustice and attributed to Copernicus's declining health. In order to ensure that Rheticus received the recognition he deserved, Giese advised him to force Petreius to
publish a revised edition that included in the introduction a biography of Copernicus that Rheticus had composed in Frauenburg as well as a brief essay by Rheticus reconciling the heliocentric system with biblical accounts. While no revised edition appeared, Rheticus sent the copies of the first edition to friends in Wittenberg. The Wittenberg astronomers followed Luther and Melanchthon's lead in rejecting heliocentrism but used Copernicus's data on the positioning of the planets to compile more accurate tables of their own. The
Catholic hierarchy was likewise unimpressed by the Polish clergyman's claims. After a copy of De revolutionibus was sent to its dedicatee Pope Paul III, in 1544 the Dominican friar Giovanni Maria Tolosani denounced Copernicus and claimed that he had not offered sufficiently strong proofs against received wisdom. In 1545, Rheticus went to Milan to present a copy of Copernicus's work to the Italian mathematician Girolamo Cardano, but was disappointed when the latter showed little enthusiasm for the Copernican theory. After recovering from a severe bout of illness
in 1547, Rheticus hoped to build on Copernicus's foundations with his own astronomical research. In 1549 he outlined his ambitions in correspondence to Giese, who had succeeded Dantsicus as bishop of Warmia two years before his own death in October 1550. In 1552, Rheticus was expelled from Leipzig after allegations that he had engaged in homosexual activities with a young boy. He eventually found refuge in Krakow but died in 1574 before he could complete his work on trigonometry. By then, Rheticus's collaboration with Copernicus had been formally acknowledged in a second edition
of De revolutionibus that appeared in Basel in 1566, but he failed to live up to his promise as Copernicus's successor. Copernicus's first great successor was the Danish astronomer Tycho Brahe, who made his own profound discovery after observing what he believed was a new star in 1572, though it was in fact a supernova caused by the explosion of a dying star. Brahe admired Copernicus but remained firmly attached to the concept of a stationary Earth. He struggled to accept Copernicus's view that the stars were millions of miles away from Earth and
instead formulated an alternative model which accepted that the planets of Mercury, Venus, Mars, Jupiter, and Saturn orbited the Sun, but suggested that the Sun itself orbited the Earth, firmly fixed in the centre of the cosmos. While Brahe hoped to support his theory by making more accurate observations, after his death his data was used by his Bohemian research assistant Johannes Kepler to provide additional supporting evidence for the Copernican system. Kepler maintained Copernicus's central thesis but used Brahe's observations to introduce elliptical
rather than circular orbits to account for discrepancies. Between 1617 and 1621, Kepler published the Epitome of Copernican Astronomy in three volumes, which combined Copernicus's heliocentric model with his own insights. A few years earlier in 1610, the Italian astronomer Galileo Galilei used his newly improved telescopes to make observations that encouraged him to openly support the Copernican system. Galileo's promotion of heliocentrism in Italy prompted renewed attention to De revolutionibus from the Roman Church. Although Copernicus's
work had enabled the formulation of the Gregorian Calendar in 1582, in February 1616, the Catholic Church officially deemed heliocentrism a heresy and placed De revolutionibus in its infamous list of banned books. A third edition was published in Amsterdam in 1617. A 1632 treatise by Galileo comparing the Ptolemaic and Copernican systems entitled Dialogue Concerning the Two Chief World Systems was immediately deemed heretical and placed on the prohibited list, leading to a high-profile heresy trial in 1633 that ensured Galileo's name was
as connected to the heliocentric theory as that of Copernicus. While the 20th century Hungarian writer Arthur Koestler dismissed Copernicus's De revolutionibus as "the book that nobody read," Owen Gingerich of Harvard University spent three decades tracking down 277 copies of its first edition, and 324 of the second, including those that had been read by Kepler and Galileo. Gingerich proved that Copernicus's work was widely read in European academic circles and passed down the generations with annotations from scholars seeking to make sense of Copernicus's
universe. In 1757, the Catholic Church removed De revolutionibus and other heliocentric books from the banned list. With Copernicus cleared of heresy, statues of him began appearing in Poland in the 19th century. The Nicolaus Copernicus Monument in front of the Polish Academy of Sciences in Warsaw was designed by the Danish sculptor Berthel Thorvaldsen and was completed in 1830. In 1853, a monument was erected in Copernicus's hometown of Toruń, then part of the kingdom of Prussia. In 2004, archaeological excavations in
Frombork uncovered the skeletal remains of a 70-year-old man later confirmed to be those of Copernicus following DNA analysis. In 2010, these remains were reinterred under a black tombstone with a representation of the heliocentric system that changed not only the world, but our understanding of the entire universe. What do you think of Nicolaus Copernicus? Should he be considered one of history's most influential scientists for his attempts to revolutionise humanity's understanding of the universe as an amateur astronomer? Could he have achieved more had he dedicated his career entirely to intellectual pursuits?
Please let us know in the comment section and in the meantime, thank you very much for watching.
