Polish Renaissance astronomer, the architect of the heliocentric planetary theory. Copernicus dedicated his remarkable work, De revolutionibus orbium caelestium (1543), to Paul III. A second edition was printed in 1563. The Roman church banned Copernicus' book eventually in 1616.

"For if the annual revolution were changed from being solar to being terrestrial, and immobility were granted to the sun, the risings and settings of the signs and of the fixed stars—whereby they become morning or evening stars—will appear in the same way; and it will be seen that the stoppings, retrogressions, and progressions of the wandering stars are not their own, but are a movement of the Earth and that they borrow the appearances of this movement. Lastly, the sun will be regarded as occupying the centre of the world. And the ratio of order in which these bodies succeed one another and the harmony of the whole world teaches us their truth, if only—as they say—we would look at the thing with both eyes." (from On the Revolutions of Heavenly Spheres, 1543)

Nicolaus Copernicus was born Niklas Koppernigk in Torún, then part of Russia. Nicolaus was the youngest child of his parents. His father, also named Niklas Koppernigk, was a successful copper trader. The mathematician Anatoly T. Fomenko has suggested, that another possible interpretation of Copernicus' name is "Cyprenicus", or "Scientist from Cyprus", because the Latin for "copper" is also "cyprus". Thus, a Cypriote could become "Kopernik" in the Slavic languages and then "Copernicus" in Latin. (Anatoly T. Fomenko in History: Fiction or Science: Chronology 3, 2007) Copernicus' mother, Barbara Watzenrode, was from prosperous local family. After Copernicus' father died, he was brought up by his uncle, Lukas Watzenrode, the bishop of Varmia. At the age of eighteen Copernicus entered the University of Cracow, where he studied mathematics and astronomy. Following the common practice, he also adopted the Latinized version of his name. During this period Copernicus learned the signs of the zodiac and how to make astronomical observations.

Copernicus then studied Greek and civil and church law in Bologna and medicine in Padua until 1503, receiving eventually his doctorate at the university of Ferrara. At that time Italy was the heart of the Renaissance, the new spirit of individuality and openness to ones own observation, the "mother of all certainty". While in Bologna, Copernicus studied privately with Professor Domenico Maria Novara, and observed with him the movements of the Moon. With the help of his uncle, Copernicus was elected in 1497 canon at the cathedral in Frombork (Frauenburg). Copernicus held this post until his death. In Rome in 1500, Copernicus observed an eclipse of the Moon.

After studies in Italy, Copernicus returned to Poland, "to the darkest corner of the world," as he said. Between 1503 and 1510, Copernicus lived primarily with his uncle at the Bishop's palace in Lidzbark. Officially Copernicus was his uncle's personal physician, but during this period he also published Latin translations of Theophylactus Simocattes, a Byzantine historian and poet, and laid down the principles of his heliocentric system in De Hypothesibus Motuum Coelestium a se Constitutis Commentariolus, which was not printed. Copernicus' translation, which appeared in 1509, had improved his knowledge of Greek, but Theophylactus' erotic letters created a slight problem for him. "Just as physicians usually moderate the bitterness of drugs by sweetening them more palatable to patients," he expained in the dedication to his uncle, "so these love letters have in like manner been rectified, with the result that they ought to receive the label 'moral' no less."

Bishop Watzenrode died in 1512. It was rumored that Teutonic knights, whom he had always opposed, eventually poisoned him. After his uncle's death Copernicus left Lidzbark and assumed his duties as canon in Frombork. In addition to being a busy administrator, Copernicus practiced medicine—which still used astrology as one of the main diagnostic tools—and in 1514 he was invited by the Church to participate in work on calendar reform. He also wrote essays in which he offered advice on currency reform. In 1519, war broke out between King Sigismund I and the Teutonic knights. During the siege of the Frombork cathedral in 1520, he made astronomical measurements, and later he organized the defense of Olsztyn castle.

On the wall surrounding the cathedral, Copernicus had in 1513 an observing tower built. In this tower, about fifty feet high, he had a work-room on the top story. However, although he used various astronomical instruments to examine the heavens, such as a quadrant, astrolabe, triquetrum, and others, he did not own a telescope—it had not yet been invented. Moreover, Frauenburg was inconveniet place for astronomical observations, because the view was often obscured by fogs rising from the sea and the general abundance of clouds.

De revolutionibus, at which Copernicus toiled nearly thirty years, appeared just before his death on May 24, 1543. It was printed by Joannes Petrejus of Nuremberg. Before the publication, Copernicus' student, his only student, Georg Joachim Rheticus (1514-1574), wrote the Narratio prima (1540), describing the principles of the new cosmology. Copernicus was buried in the Frombork Cathedral; his remains there were identified in 2008.

De revolutionibus was not put on the list of forbidden books for decades, partly because the printer added a disclaimer to the work—"For these hypotheses need not be true nor even probable," stated the writer, Andreas Osiander, in the unauthorized preface, but merely a handy way to predict the movements of the planets. "Let nobody expect anything certain from astronomy, which cannot furnish it, least he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than when he entered it." In 1616 the church declared Copernicus' theory "false and altogether opposed to Holy Scripture", and it took more than two hundred years before the works of Copernicus and of Galileo were removed from the Index. However, the church needed Copernicus' calculations to date Easter more precisely.

With his heliocentric astronomy Copernicus removed the earth from its central position. Challenging the dominant geocentric system, he saw that the earth is a planet, a heavenly body, too, and revolves around the sun. "My teacher [Copernicus] is convinced, however, that the rejected method of the Sun's rule in the realm of nature must be revived," wrote Rheticus.

Before his manuscript was published, Copernicus discussed cautiously of his theory, but in semi-religious Platonic and Neo-Platonic circles the idea was not a novelty. Noteworthy, regarding the centre of the universe, the prominent reformist churchmen, Martin Luther and Phillipp Melanchthon, were as dogmatic as their Roman Catholic colleagues: "This fool wants to turn the entire art of astronomy upside down!" said Luther. "But as the Holy Scripture show, Joshua ordered the sun, and not the Earth, to halt!" Rheticus was also a Lutheran, but this did not stop him from advocating the idea of heliocentricism.

When Leonardo united microcosm and macrocosm in his famous drawing on the Vitruvian man, Copernicus removed the earth—and man—from the God-granted seat. Besides being contrary to the Scripture, this theory was against common-sense observation: the sun appears to move around the earth from east to west. "Lift up your eyes then, reader, here with me / To the high spheres, straight to that region where / One motion of the sun strikes on the other," wrote Dante on the sun and the planets in his Divine Comedy, which followed the Ptolemaic model of the universe. Until the appearance of De revolutionibus, Ptolemy's Almagest had been the most influential textbook of astronomy for more than a thousand years. O. Neugebauer has remarked in The Exact Sciences in Antiquity (1962) that De revolutionibus and Almagest are parallel works "chapter by chapter, theorem by theorem and table by table." Copernicus' star catalogue is basically identical to the catalogue of Ptolemy.

Copernicus' work was highly technical and only the first 5 percent dealt with the heliocentric theory. But it was not "the book that nobody read" as Arthur Koestler said in The Sleepwalkers (1959). Koestler's statement was proved wrong by Owen Gingerich in The Book Nobody Read (2004), which shows that it was widely read and studied. However, De revolutionibus—or Kepler's Astronomia nova (1609) or Galileo's Dialogo sopra i due massimi sistemi del mondo (1632)—never held similar authoritative status as the Almagest.

In spite of his new system of planetary motion, Copernicus was a devoted admirer of the ancients, and his original aim was to revise Ptolemy so that it was more in line with Aristotelian principles. Actually, his theory was a return to a model rejected in ancient times. Galileo called in Letter to the Grand Duchess Christina Copernicus the theory's "restorer and confirmer". The Polish astronomer knew well that the Greek mathematician and astronomer Aristarchus of Samos (ca. 310-ca. 230 BC) had suggested that the planets' motions were governed by the sun.

The Ptolemaic system appeared to Copernicus to be empirically adequate but he criticized it for theoretical if not aesthetic reasons. Consisting mainly of a set of mathematical means for calculating heavenly movements, Almagest did not solve "the structure of the universe and the true symmetry of its parts," as Copernicus said in De revolutionibus. Also the great Islamic philosopher Averroes (1126-98) had noted much earlier in his Commentary on Aristotle's Book on the Heavens (c. 1180), that the "model that has been developed in the times which we live accords with the computations not with existence." However, Copernicus thought that geometrical astronomy offered the key to the understanding of "the movements of the world machine", not the work of the philosophers, "who otherwise examined so precisely the most insignificant trifles of this world."

According to Ptolemy, the planets move in epicycles, circles whose centers orbit the earth. "Having become aware of these defects," Copernicus wrote, "I often considered whether there could perhaps be found a more reasonable arrangement of circles, from which every apparent inequality would be derived and in which everything would move uniformly about its proper center, as the rule of absolute motion requires." Like Ptolemy, Copernicus believed in the perfection of the circular motion, and he also saw the sun as "the lantern of the universe". Copernicus introduced additional circles and motions to his model, to make its predictions as accurate as possible. This did not make his model more simpler, although it provided a rational explanation for the peculiar loops (retrogressions) of the planets. Especially the odd behavior of Mars had caused great difficulties for Ptolemaic astronomers. In Tycho Brahe's (1546-1601) system the traditional planets orbited the sun, and the sun orbited the earth. Kepler dropped the epicycles entirely and transformed the orbits into ellipses.

"What a Copernicus or a Darwin really achieved was not the discovery of a true theory but a fertile new point of view," said Ludwig Wittgenstein in Culture and Value (1980). Copernicus' new astronomical paradigm radically transformed the way scientists saw the universe but it did not change the language or our everyday perception: we still say "the sun rises" and behave as if the sun turns and we remain immobile.

For further reading: The Sleepwalkers by Arthur Koestler (1959); Moving Heaven and Earth: Copernicus and the Solar System by John Henry (2001); Nicolaus Copernicus and the Founding of Modern Astronomy by Todd Goble (2003) The Book Nobody Read: Chasing the Revolutions of Nicolaus Copernicus by Owen Gingerich (2004); Uncentering the Earth: Copernicus and The Revolutions of the Heavenly Spheres by William T. Vollmann (2006); A More Perfect Heaven: How Copernicus Revolutionized the Cosmos by Dava Sobel (2011)  

Selected works:

• De monetae cudendae ratione, 1526 - Treatise on Coining Money, 1965 (translated, edited and published by George Albert Moore)
• De lateribus et angulis triangulorum, 1542
• De revolutionibus orbium caelestium libri VI, 1543 - On the Revolutions of Heavenly Spheres, 1939 (translated by Charles Glenn Wallis) / On the Revolutions of the Heavenly Spheres, 1976 (translated by A.M. Duncan) / On the Revolutions, 1978  (translation and commentary by Edward Rosen)
• Three Copernican Treatises: The Commentariolus of Copernicus, the Letter against Werner, the Narratio prima of Rheticus, 1939 (translated by Edward Rosen)
• Nikolaus Kopernikus Gesamtausgabe, 1944 (ed. Fritz Kubach)
• Complete Works, 1972-1992 (4 vols.)
• Nicolaus Copernicus Gesamtausgabe, 1974-2007 (9 vols., ed. Heribert M. Nobis)
• Minor Works, 1992 (translated by Edward Rosen with the assistance of Erna Hilfstein)