Heliocentric Universe

Heliocentrism (lower panel) in comparison to the geocentric model (upper panel)

Heliocentrism, or heliocentricism,^[1] is the astronomical model in which the Earth and planets revolve around a relatively stationary Sun at the center of the Solar System. The word comes from the Greek (ἥλιος helios "sun" and κέντρον kentron "center"). Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center. The notion that the Earth revolves around the Sun had been proposed as early as the 3rd century BC by Aristarchus of Samos,^[2] but had received no support from most other ancient astronomers.

It was not until the 16th century that a fully predictive mathematical model of a heliocentric system was presented, by the Renaissance mathematician, astronomer, and Catholic cleric Nicolaus Copernicus of Poland, leading to the Copernican Revolution. In the following century, Johannes Kepler elaborated upon and expanded this model to include elliptical orbits, and supporting observations made using a telescope were presented by Galileo Galilei.

With the observations of William Herschel, Bessel and others, astronomers realized that the sun was not the center of the universe and by the 1920s Edwin Hubble had shown that it was part of a galaxy (see milky way) that was only one of many billions.

Early developments[link]

To anyone who stands and looks up at the sky, it seems that the Earth stays in one place while everything in the sky rises in the east and sets in the west once a day. With more scrutiny, however, one will observe more complicated movements. The positions at which the Sun and moon rise change over the course of a year, some planets and stars do not appear at all for many months, and planets sometimes appear to have moved in the reverse direction for a while, relative to the background stars (retrograde motion).

As these motions became better understood, more elaborate descriptions were required, the most famous of which was the geocentric Ptolemaic system, which achieved its full expression in the 2nd century. The Ptolemaic system was a sophisticated astronomical system that managed to calculate the positions for the planets to a fair degree of accuracy.^[3] Ptolemy himself, in his Almagest, points out that any model for describing the motions of the planets is merely a mathematical device, and since there is no actual way to know which is true, the simplest model that gets the right numbers should be used.^[4] However, he rejected the idea of a spinning earth as absurd as he believed it would create huge winds. His planetary hypotheses were sufficiently real that the distances of moon, sun, planets and stars could be determined by treating orbits' celestial spheres as contiguous realities. This made the stars' distance less than 20 Astronomical Units,^[5] a regression, since Aristarchus of Samos's heliocentric scheme had centuries earlier necessarily placed the stars at least two orders of magnitude more distant.

Greek and Hellenistic world[link]

Pythagoreans

The non-geocentric model of the Universe was proposed by the Pythagorean philosopher Philolaus (d. 390 BCE). According to Philolaus, there was at the center of the Universe a "central fire" around which the Earth, Sun, Moon and Planets revolved in uniform circular motion. This system postulated the existence of a counter-earth collinear with the Earth and central fire, with the same period of revolution around the central fire as the Earth. The Sun revolved around the central fire once a year, and the stars were stationary. The Earth maintained the same hidden face towards the central fire, rendering both it and the "counter-earth" invisible from Earth. The Pythagorean concept of uniform circular motion remained unchallenged for approximately the next 2000 years, and it was to the Pythagoreans that Copernicus referred to show that the notion of a moving Earth was neither new nor revolutionary.^[6]

Kepler gave an alternative explanation of the Pythagoreans' "central fire" as the sun, "as most sects purposely hid[e] their teachings".^[7]

Heraclides of Pontus (4th century BCE) explained the apparent daily motion of the celestial sphere through the rotation of the Earth. It used to be thought that he believed Mercury and Venus to revolve around the Sun, which in turn (along with the other planets) revolves around the Earth.^[8] Macrobius Ambrosius Theodosius (CE 395–423) later described this as the "Egyptian System," stating that "it did not escape the skill of the Egyptians," though there is no other evidence it was known in ancient Egypt.^{[9][verification needed][10][verification needed]}

Aristarchus of Samos

Aristarchus's 3rd century BC calculations on the relative sizes of the Earth, Sun and Moon, from a 10th century CE Greek copy

The first person known to have proposed a heliocentric system, however, was Aristarchus of Samos (c. 270 BCE). Like Eratosthenes, Aristarchus calculated the size of the Earth, and measured the size and distance of the Moon and Sun, in a treatise which has survived. From his estimates, he concluded that the Sun was six to seven times wider than the Earth and thus hundreds of times more voluminous. His writings on the heliocentric system are lost, but some information is known from surviving descriptions and critical commentary by his contemporaries, such as Archimedes. Some have suggested that his calculation of the relative size of the Earth and Sun led Aristarchus to conclude that it made more sense for the Earth to be moving than for the huge Sun to be moving around it. Though the original text has been lost, a reference in Archimedes' book The Sand Reckoner describes another work by Aristarchus in which he advanced an alternative hypothesis of the heliocentric model. Archimedes wrote:

You King Gelon are aware the 'universe' is the name given by most astronomers to the sphere the center of which is the center of the Earth, while its radius is equal to the straight line between the center of the Sun and the center of the Earth. This is the common account as you have heard from astronomers. But Aristarchus has brought out a book consisting of certain hypotheses, wherein it appears, as a consequence of the assumptions made, that the universe is many times greater than the 'universe' just mentioned. His hypotheses are that the fixed stars and the Sun remain unmoved, that the Earth revolves about the Sun on the circumference of a circle, the Sun lying in the middle of the orbit, and that the sphere of fixed stars, situated about the same center as the Sun, is so great that the circle in which he supposes the Earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface.^[11]

Aristarchus thus believed the stars to be very far away, and saw this as the reason why there was no visible parallax, that is, an observed movement of the stars relative to each other as the Earth moved around the Sun. The stars are in fact much farther away than the distance that was generally assumed in ancient times, which is why stellar parallax is only detectable with telescopes.

Archimedes says that Aristarchus made the stars' distance larger, suggesting that he was answering the natural objection that heliocentrism requires stellar parallactic oscillations. He apparently agreed to the point but placed the stars so distant as to make the parallactic motion invisibly minuscule. Thus heliocentrism opened the way for realization that the universe was larger than the geocentrists taught.^[12]

Seleucus of Seleucia

Since Plutarch mentions the 'followers of Aristarchus' in passing, there were likely other astronomers in the Classical period who also espoused heliocentrism, but whose work is now lost to us. The only other astronomer from antiquity known by name who is known to have supported Aristarchus' heliocentric model was Seleucus of Seleucia (b. 190 BCE), a Hellenistic astronomer who flourished a century after Aristarchus in the Seleucid empire.^[13] Seleucus adopted the heliocentric system of Aristarchus and is said to have proved the heliocentric theory.^[14] According to Bartel Leendert van der Waerden, Seleucus may have proved the heliocentric theory by determining the constants of a geometric model for the heliocentric theory and by developing methods to compute planetary positions using this model. He may have used early trigonometric methods that were available in his time, as he was a contemporary of Hipparchus.^[15] A fragment of a work by Seleucus has survived in Arabic translation, which was referred to by Rhazes (b. 865).^[16]

Alternatively, his explanation may have involved the phenomenon of tides,^[17] which he supposedly theorized to be caused by the attraction to the Moon and by the revolution of the Earth around the Earth-Moon 'center of mass'.

Western Christendom[link]

Nicholas of Cusa, 15th century, asked whether there was any reason to assert heliocentrism

There were occasional speculations about heliocentrism in Europe before Copernicus. In Roman Carthage, the pagan Martianus Capella (5th century) expressed the opinion that the planets Venus and Mercury did not go about the Earth but instead circled the Sun.^[18] Capella's model was discussed in the Early Middle Ages by various anonymous 9th-century commentators^[19] and Copernicus mentions him as an influence on his own work.^[20]

During the Late Middle Ages, Bishop Nicole Oresme discussed the possibility that the Earth rotated on its axis, while Cardinal Nicholas of Cusa in his Learned Ignorance asked whether there was any reason to assert that the Sun (or any other point) was the center of the universe. In parallel to a mystical definition of God, Cusa wrote that "Thus the fabric of the world (machina mundi) will quasi have its center everywhere and circumference nowhere."^[21]

India[link]

Aryabhata (476–550), in his magnum opus Aryabhatiya (499), propounded a planetary model in which the Earth was taken to be spinning on its axis and the periods of the planets were given with respect to the Sun. He accurately calculated many astronomical constants, such as the periods of the planets, times of the solar and lunar eclipses, and the instantaneous motion of the Moon.^{[22][page needed][23][page needed]} Early followers of Aryabhata's model included Varahamihira, Brahmagupta, and Bhaskara II.

Nilakantha Somayaji (1444–1544), in his Aryabhatiyabhasya, a commentary on Aryabhata's Aryabhatiya, developed a computational system for a partially heliocentric planetary model, in which the planets orbit the Sun, which in turn orbits the Earth, similar to the Tychonic system later proposed by Tycho Brahe in the late 16th century. In the Tantrasangraha (1500), he further revised his planetary system, which was mathematically more accurate at predicting the heliocentric orbits of the interior planets than both the Tychonic and Copernican models,^[22][24] but like Indian astronomy in general fell short of proposing models of the universe.^[25] Nilakantha's planetary system also incorporated the Earth's rotation on its axis.^[26] Most astronomers of the Kerala school of astronomy and mathematics seem to have accepted his planetary model.^[27][28]

Medieval Iranian and Islamic world[link]

An illustration from al-Biruni's astronomical works, explains the different phases of the moon, with respect to the position of the sun. Al-Biruni suggested that if the Earth rotated on its axis this would be consistent with astronomical theory. He discussed heliocentrism but considered it was a philosophical problem.

Because of the scientific dominance of the Ptolemaic system in Islamic astronomy, the Muslim astronomers accepted unanimously the geocentric model.^[29] However, several Muslim scholars questioned the Earth's apparent immobility^[30][31] and centrality within the universe.^[32] Alhazen wrote a scathing critique of Ptolemy's model in his Doubts on Ptolemy (c. 1028), which some have interpreted to imply he was criticizing Ptolemy's geocentrism,^[33] but most agree that he was actually criticizing the details of Ptolemy's model rather than his geocentrism.^[34] Alhazen did, however, later propose the Earth's rotation on its axis in The Model of the Motions (c. 1038).^[35]

Abu Rayhan Biruni (b. 973) discussed the possibility of whether the Earth rotated about its own axis and around the Sun, but in his Masudic Canon, he set forth the principles that the Earth is at the center of the universe and that it has no motion of its own.^[36] He was aware that if the Earth rotated on its axis and around the Sun, this would be consistent with his astronomical parameters,^[37] but he considered this a philosophical problem rather than a mathematical one.^[38] At the Maragha observatory, Najm al-Dīn al-Qazwīnī al-Kātibī (d. 1277), in his Hikmat al-'Ain, wrote an argument for a heliocentric model, but later abandoned the model. Qutb al-Din Shirazi (b. 1236) also discussed the possibility of heliocentrism, but rejected it.^[39] Ibn al-Shatir (b. 1304) developed a geocentric system that employed mathematical techniques, such as the Tusi-couple and Urdi lemma, that were almost identical to those Nicolaus Copernicus later employed in his heliocentric system, implying that its mathematical model was influenced by the Maragha school.^{[40][41][42][43][44]} At the Maragha and Samarkand observatories, the Earth's rotation was discussed by Tusi (b. 1201) and Qushji (b. 1403); the arguments and evidence they used resemble those used by Copernicus to support the Earth's motion.^[30][31]

However, it remains a fact that the Maragha school never made the big leap to heliocentrism.^[45] In addition, the influence of the Maragha school on Copernicus remains speculative, since there is no documentary evidence to prove it. The possibility that Copernicus independently developed the Tusi couple remains open, since no researcher has yet proven that he knew about Tusi's work or the Maragha school.^[45][46] It has been argued that, given some differences between the two models, it is more likely that Copernicus could have taken the ideas found in the Tusi couple from Proclus's Commentary on the First Book of Euclid.^[47] Another possible source for Copernicus's knowledge is the Questiones de Spera of Nicole Oresme, who described how a reciprocating linear motion of a celestial body could be produced by a combination of circular motions similar to those proposed by al-Tusi.^[48]

Nevertheless, heliocentrism also can be found in the works of Muslim theologians and philosophers such as Fakhr al-Din al-Razi (b. 1149), Al-Zamakhshari (b. 1075), and Ottoman Sheikh ul-Islam Ebussuud Efendi (b.1490).

In his major work Tafsir al-Kabir, Fakhr al-Din al-Razi defends ideas of heliocentrism with only difference that the Sun is not mentioned as a static object or as a centre of the Universe:

Even though the Earth is described as a bed in this verse, in the other verse it is portrayed as a sphere. Spherical earth is revolving around the Sun. If questioned "How people and objects can stand on the Earth if the Earth, as a sphere, revolving around the Sun?", my answer will be that the Earth is such a huge sphere where flat surfaces appear."^[49]

Al-Zamakhshari in his work Al-Kashshaaf^[50] and Ebussuud Efendi in Irshadu'l-Akli's-Selim^[51] provide similar explanations which support heliocentrism.

Copernican revolution[link]

Astronomical model[link]

Nicolaus Copernicus, 16th century, described the first computational system explicitly tied to a heliocentric model

In the 16th century, Nicolaus Copernicus De revolutionibus presented a full discussion of a heliocentric model of the universe in much the same way as Ptolemy's Almagest had presented his geocentric model in the 2nd century. Copernicus discussed the philosophical implications of his proposed system, elaborated it in full geometrical detail, used selected astronomical observations to derive the parameters of his model, and wrote astronomical tables which enabled one to compute the past and future positions of the stars and planets. In doing so, Copernicus moved heliocentrism from philosophical speculation to predictive geometrical astronomy—in reality it did not predict the planets' positions any better than the Ptolemaic system.^[52] This theory resolved the issue of planetary retrograde motion by arguing that such motion was only perceived and apparent, rather than real: it was a parallax effect, as a car that one is passing seems to move backwards against the horizon. This issue was also resolved in the geocentric Tychonic system; the latter, however, while eliminating the major epicycles, retained as a physical reality the irregular back-and-forth motion of the planets, which Kepler characterized as a "pretzel".^[53]

Copernicus cited Aristarchus in an early (unpublished) manuscript of De Revolutionibus (which still survives) so he was clearly aware of at least one previous proponent of the heliocentric thesis. However, in the published version he restricts himself to noting that in works by Cicero he had found an account of the theories of Hicetas and that Plutarch had provided him with an account of the Pythagoreans Heraclides Ponticus, Philolaus, and Ecphantus. These authors had proposed a moving earth, which did not, however, revolve around a central sun.

Religious attitudes to heliocentrism[link]

Heliocentrism had been in conflict with religion before Copernicus. One of the few pieces of information we have about the reception of Aristarchus's heliocentric system comes from a passage in Plutarch's dialogue, Concerning the Face which Appears in the Orb of the Moon. According to one of Plutarch's characters in the dialogue, the philosopher Cleanthes had held that Aristarchus should be charged with impiety for "moving the hearth of the world".^[54] In fact, however, Aristarchus's heliocentrism appears to have attracted little attention, religious or otherwise, until Copernicus revived and elaborated it.^[55]

Circulation of Commentariolus (before 1533)[link]

The first information about the heliocentric views of Nicolaus Copernicus were circulated in manuscript. Although only in manuscript, Copernicus' ideas were well known among astronomers and others. His ideas contradicted the then-prevailing understanding of the Bible. In the King James Bible Chronicles 16:30 state that "the world also shall be stable, that it be not moved." Psalm 104:5 says, "[the Lord] Who laid the foundations of the earth, that it should not be removed for ever." Ecclesiastes 1:5 states that "The sun also ariseth, and the sun goeth down, and hasteth to his place where he arose."

Nonetheless, in 1533, Johann Albrecht Widmannstetter delivered in Rome a series of lectures outlining Copernicus' theory. The lectures were heard with interest by Pope Clement VII and several Catholic cardinals.^[56] On November 1, 1536, Archbishop of Capua Nikolaus von Schönberg wrote a letter to Copernicus from Rome encouraging him to publish a full version of his theory.

However, in 1539, Martin Luther said:

"There is talk of a new astrologer who wants to prove that the earth moves and goes around instead of the sky, the sun, the moon, just as if somebody were moving in a carriage or ship might hold that he was sitting still and at rest while the earth and the trees walked and moved. But that is how things are nowadays: when a man wishes to be clever he must . . . invent something special, and the way he does it must needs be the best! The fool wants to turn the whole art of astronomy upside-down. However, as Holy Scripture tells us, so did Joshua bid the sun to stand still and not the earth."

This was reported in the context of a conversation at the dinner table and not a formal statement of faith. Melanchthon, however, opposed the doctrine over a period of years.

Publication of de Revolutionibus (1543)[link]

Nicolaus Copernicus published the definitive statement of his system in De Revolutionibus in 1543. Copernicus began to write it in 1506 and finished it in 1530, but did not publish it until the year of his death. Although he was in good standing with the Church and had dedicated the book to Pope Paul III, the published form contained an unsigned preface by Osiander defending the system and arguing that it was useful for computation even if its hypotheses were not necessarily true. Possibly because of that preface, the work of Copernicus inspired very little debate on whether it might be heretical during the next 60 years. There was an early suggestion among Dominicans that the teaching of heliocentrism should be banned, but nothing came of it at the time.

Some years after the publication of De Revolutionibus John Calvin preached a sermon in which he denounced those who "pervert the course of nature" by saying that "the sun does not move and that it is the earth that revolves and that it turns".^[57] On the other hand, Calvin is not responsible for another famous quotation which has often been misattributed to him:

"Who will venture to place the authority of Copernicus above that of the Holy Spirit?"

It has long been established that this line cannot be found in any of Calvin's works.^[58][59][60] It has been suggested^[61] that the quotation was originally sourced from the works of Lutheran theologian Abraham Calovius.

Tycho Brahe's geo-heliocentric system c. 1587[link]

In this depiction of the Tychonic system, the objects on blue orbits (the Moon and the Sun) revolve around the Earth. The objects on orange orbits (Mercury, Venus, Mars, Jupiter, and Saturn) revolve around the Sun. Around all is a sphere of fixed stars, located just beyond Saturn.

Prior to the publication of De Revolutionibus, the widely accepted system had been that which was proposed by Ptolemy, in which the Earth was the center of the universe and all celestial bodies orbited it. Tycho Brahe, arguably the most accomplished astronomer of his time, advocated against Copernicus's heliocentric system and for an alternative to the Ptolemaic geocentric system: a geo-heliocentric system now known as the Tychonic system in which the five then known planets orbit the sun, while the sun and the moon orbit the earth.

Tycho appreciated the Copernican system, but objected to the idea of a moving Earth on the basis of physics, astronomy, and religion. The Aristotelian physics of the time (modern Newtonian physics was still a century away) offered no physical explanation for the motion of a massive body like Earth, whereas it could easily explain the motion of heavenly bodies by postulating that they were made of a different sort substance called aether that moved naturally. So Tycho said that the Copernican system “... expertly and completely circumvents all that is superfluous or discordant in the system of Ptolemy. On no point does it offend the principle of mathematics. Yet it ascribes to the Earth, that hulking, lazy body, unfit for motion, a motion as quick as that of the aethereal torches, and a triple motion at that.”^[62] Likewise, Tycho took issue with the vast distances to the stars that Aristarchus and Copernicus had assumed in order to explain the lack of any visible parallax. Tycho had measured the apparent sizes of stars (now known to be illusory – see stellar magnitude), and used geometry to calculate that in order to both have those apparent sizes and be as far away as heliocentrism required, stars would have to be huge (much larger than the sun; the size of Earth's orbit or larger). Regarding this Tycho wrote, “Deduce these things geometrically if you like, and you will see how many absurdities (not to mention others) accompany this assumption [of the motion of the earth] by inference.”^[63] He also cited the Copernican system's "opposition to the authority of Sacred Scripture in more than one place" as a reason why one might wish to reject it, and observed that his own geoheliocentric alternative “offended neither the principles of physics nor Holy Scripture”.^[64]

The Jesuit astronomers in Rome were at first unreceptive to Tycho's system; the most prominent, Clavius, commented that Tycho was "confusing all of astronomy, because he wants to have Mars lower than the Sun."^[65] However, after the advent of the telescope showed problems with some geocentric models (by demonstrating that Venus circles the sun, for example), the Tychonic system and variations on that system became very popular among geocentrists, and the Jesuit astronomer Giovanni Battista Riccioli would continue Tycho's use of physics, stellar astronomy (now with a telescope), and religion to argue against heliocentrism and for Tycho's system well into the seventeenth century (see Riccioli).

Publication of Starry messenger (1610)[link]

In the 17th century AD Galileo Galilei opposed the Roman Catholic Church by his strong support for heliocentrism

Galileo was able to look at the night sky with the newly invented telescope. Then he published his discoveries in Sidereus Nuncius including (among other things) the moons of Jupiter and that Venus exhibited a full range of phases. These discoveries were not consistent with the Ptolemeic model of the solar system. As the Jesuit astronomers confirmed Galileo's observations, the Jesuits moved toward Tycho's teachings.^[66]

Publication of Letter to the Grand Duchess (1615)[link]

In a Letter to the Grand Duchess Christina, Galileo defended heliocentrism, and claimed it was not contrary to Scriptures (see Galileo affair). He took Augustine's position on Scripture: not to take every passage literally when the scripture in question is a book of poetry and songs, not a book of instructions or history. The writers of the Scripture wrote from the perspective of the terrestrial world, and from that vantage point the sun does rise and set. In fact, it is the Earth's rotation which gives the impression of the sun in motion across the sky.

The decree of 1616[link]

The Letter to the Grand Duchess Christina prompted the papal authorities to decide whether heliocentrism was acceptable. Galileo was summoned to Rome to defend his position. The Church accepted the use of heliocentrism as a calculating device, but opposed it as a literal description of the solar system. Cardinal Robert Bellarmine himself considered that Galileo's model made "excellent good sense" on the ground of mathematical simplicity; that is, as a hypothesis (see above). And he said:

"If there were a real proof that the Sun is in the center of the universe, that the Earth is in the third sphere, and that the Sun does not go round the Earth but the Earth round the Sun, then we should have to proceed with great circumspection in explaining passages of Scripture which appear to teach the contrary, and we should rather have to say that we did not understand them than declare an opinion false which has been proved to be true. But I do not think there is any such proof since none has been shown to me."

—Koestler (1959), p. 447–448

Bellarmine supported a ban on the teaching of the idea as anything but hypothesis. In 1616 he delivered to Galileo the papal command not to "hold or defend" the heliocentric idea.^[67] The Vatican files suggest that Galileo was forbidden to teach heliocentrism in any way whatsoever, but whether this ban was known to Galileo is a matter of dispute.^[68]

Publication of Epitome astronomia Copernicanae (1617–1621)[link]

In Astronomia nova (1609), Johannes Kepler had used an elliptical orbit to explain the motion of Mars. In Epitome astronomia Copernicanae he developed a heliocentric model of the solar system in which all the planets have elliptical orbits. This provided significantly increased accuracy in predicting the position of the planets. Kepler's ideas were not immediately accepted. Galileo for example completely ignored Kepler's work. Kepler proposed heliocentrism as a physical description of the solar system and Epitome astronomia Copernicanae was placed on the index of prohibited books despite Kepler being a Protestant.

Publication of Dialogue concerning the two chief world systems[link]

Pope Urban VIII encouraged Galileo to publish the pros and cons of Heliocentrism. In the event, Galileo's Dialogue concerning the two chief world systems clearly advocated heliocentrism and appeared to make fun of the Pope. Urban VIII became hostile to Galileo and he was again summoned to Rome.^[69] Galileo's trial in 1633 involved making fine distinctions between "teaching" and "holding and defending as true". For advancing heliocentric theory Galileo was forced to recant Copernicanism and was put under house arrest for the last few years of his life.

According to J. L. Heilbron,^[70] informed contemporaries of Galileo's:

"appreciated that the reference to heresy in connection with Galileo or Copernicus had no general or theological significance."

Subsequent developments[link]

Rene Descartes postponed, and ultimately never finished, his treatise The World, which included a heliocentric model.^[71] But ultimately the Galileo affair did little to slow the spread of heliocentrism across Europe, as Kepler's Epitome of Copernican Astronomy became increasingly influential in the coming decades.^[72] By 1686 the model was well enough established that the general public was reading about it in Conversations on the Plurality of Worlds, published in France by Bernard le Bovier de Fontenelle and translated into English and other languages in the coming years. It has been called "one of the first great popularizations of science."^[71]

In 1687, Isaac Newton published Philosophiæ Naturalis Principia Mathematica, which provided an explanation for Kepler's laws in terms of universal gravitation and what came to be known as Newton's laws of motion. This placed heliocentrism on a firm theoretical foundation, although Newton's heliocentrism was of a somewhat modern kind. Already in the mid-1680s he recognized the "deviation of the Sun" from the centre of gravity of the solar system.^[73] For Newton it was not precisely the centre of the Sun or any other body that could be considered at rest, but "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line" (Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest)^[74]

Meanwhile the Church remained opposed to heliocentrism as a literal description, but this did not by any means imply opposition to all astronomy; indeed, it needed observational data to maintain its calendar. In support of this effort it allowed the cathedrals themselves to be used as solar observatories called meridiane; i.e., they were turned into "reverse sundials", or gigantic pinhole cameras, where the Sun's image was projected from a hole in a window in the cathedral's lantern onto a meridian line.

In 1664, Pope Alexander VII published his Index Librorum Prohibitorum Alexandri VII Pontificis Maximi jussu editus (Index of Prohibited Books, published by order of Alexander VII, P.M.) which included all previous condemnations of heliocentric books.^[75]

In the mid-eighteenth century the Church's opposition began to fade. An annotated copy of Newton's Principia was published in 1742 by Fathers le Seur and Jacquier of the Franciscan Minims, two Catholic mathematicians, with a preface stating that the author's work assumed heliocentrism and could not be explained without the theory. In 1758 the Catholic Church dropped the general prohibition of books advocating heliocentrism from the Index of Forbidden Books.^[76] Pope Pius VII approved a decree in 1822 by the Sacred Congregation of the Inquisition to allow the printing of heliocentric books in Rome.

Heliocentrism and Judaism[link]

Already in the Talmud, Greek philosophy and science under general name "Greek wisdom" were considered dangerous. They were put under ban then and later for some periods (for example, Shlomo ben Aderet prohibited study of philosophy in 1305). Possibly due to this the system of Nicolaus Copernicus did not cause furious resistance, although it was found to be contradicting verses of Tanakh (Jewish Bible).

The first to mention the new system was Maharal of Prague, although he did not mention Copernicus, the author of the system. In his book "Be'er ha-Golah", in 1593 Maharal used the appearance of the new system to show that scientific theories are not reliable enough – even astronomy was turned upside-down.^[77]

Copernicus is mentioned for the first time in Hebrew in the books of David Gans (1541–1613), who worked with Tycho Brahe and Johannes Kepler. Gans wrote two books on astronomy: a short one "Magen David" (1612) and a full one "Nehmad veNaim" (published only in 1743). He described objectively three systems: Ptolemy, Copernicus and of Tycho Brahe without taking sides.

In 1629 a new Hebrew book "Elim" by Joseph Solomon Delmedigo (1591–1655) appeared. The author says that the arguments of Copernicus are so strong, that only an imbecile will not accept them.^[78] Delmedigo studied at Padua and was acquainted with Galileo.^[79]

The following wave of Hebrew literature on the subject is from the 18th century. Most of its authors were for Copernicus, although David Nieto and Tobias Cohn were exceptions. These two authors gave the same reason for opposing heliocentrism—namely, contradiction of the Bible—although Nieto merely rejected the new system on those grounds without much passion, whereas Hacohen went so far as to call Copernicus «a first-born of Satan». Hacohen also mentions the fact that the Sages of Talmud derived the Hebrew name of Earth from the verb "run".^[79]

In later periods there were no explicit attacks on heliocentrism, although some Rabbis were not sure of it.^[80][81]

In the 20th century R. M.M. Schneerson suggested that the theory of relativity makes the question obsolete, as he writes, "based on the understanding of science at this point".^[82]

The view of modern science[link]

Kepler's laws of planetary motion were used as arguments^{[citation needed]} in favor of the heliocentric hypothesis. Three apparent proofs of the heliocentric hypothesis were provided in 1727 by Bradley, in 1838 by Friedrich Wilhelm Bessel and in 1851 by Foucault. Bessel proved that parallax of a star was greater than zero. He measured the parallax of 0.314 arcseconds of a star named 61 Cygni. In the same year Friedrich Georg Wilhelm Struve and Thomas Henderson measured the parallaxes of other stars, Vega and Alpha Centauri.

The thinking that the heliocentric view was also not true in a strict sense was achieved in steps. That the Sun was not the center of the universe, but one of innumerable stars, was strongly advocated by the mystic Giordano Bruno. Over the course of the 18th and 19th centuries, the status of the Sun as merely one star among many became increasingly obvious. By the 20th century, even before the discovery that there are many galaxies, it was no longer an issue.

The concept of an absolute velocity, including being "at rest" as a particular case, is ruled out by the principle of relativity, also eliminating any obvious "center" of the universe as a natural origin of coordinates. Some forms of Mach's principle consider the frame at rest with respect to the distant masses in the universe to have special properties.

Even if the discussion is limited to the solar system, the Sun is not at the geometric center of any planet's orbit, but rather approximately at one focus of the elliptical orbit. Furthermore, to the extent that a planet's mass cannot be neglected in comparison to the Sun's mass, the center of gravity of the solar system is displaced slightly away from the center of the Sun.^[74] (The masses of the planets, mostly Jupiter, amount to 0.14% of that of the Sun.) Therefore a hypothetical astronomer on an extrasolar planet would observe a small "wobble" in the Sun's motion.

[edit] Modern use of geocentric and heliocentric

In modern calculations the terms "geocentric" and "heliocentric" are often used to refer to coordinate systems that are chosen for practical reasons. In such systems the origin in the center of mass of the Earth, of the Earth-Moon system, of the Sun, of the Sun plus the major planets, or of the entire solar system can be selected. However, such selection of "geocentric" or "heliocentric" coordinates has only practical implications and not philosophical or physical ones.

The view of the public[link]

A proportion of the public still believes in the geocentric model. Approximately one in five Americans and Britons believe that the Sun revolves around the Earth, according to surveys in 1999, 2006.^[83][84] Approximately one third of Russians believe in the geocentric model, according to a survey in 2011.^[85]

See also[link]

• Geocentrism
• Copernican Revolution (metaphor)
• Copernican principle

External links[link]

• Does Heliocentrism Mean That the Sun is Stationary?
• Heliocentric Pantheon
• The Copernican Model: a Sun Centered Solar System
• Animated Copernican (HELIOCENTRIC VIEW) and Tychonian orreries; click on "Copernican" or "Tychonian" in the lower Right corner

Notes[link]

References[link]

Nicolaus Copernicus
Portrait, 1580, Toruń Old Town City Hall
Born	(1473-02-19)19 February 1473 Thorn (Toruń), Royal Prussia, Kingdom of Poland
Died	24 May 1543(1543-05-24) (aged 70) Frauenburg (Frombork), Prince-Bishopric of Warmia, Royal Prussia, Kingdom of Poland
Fields	Mathematics, astronomy, canon law, medicine, economics
Alma mater	Kraków University, Bologna University, University of Padua, University of Ferrara
Known for	Heliocentrism, Copernicus' Law
Signature

Nicolaus Copernicus (German: Nikolaus Kopernikus; Italian: Nicolò Copernico; Polish:  Mikołaj Kopernik (help·info); in his youth, Niclas Koppernigk;^[1] 19 February 1473 – 24 May 1543) was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe.^[2]

Copernicus' epochal book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), published just before his death in 1543, is often regarded as the starting point of modern astronomy and the defining epiphany that began the scientific revolution. His heliocentric model, with the Sun at the center of the universe, demonstrated that the observed motions of celestial objects can be explained without putting Earth at rest in the center of the universe. His work stimulated further scientific investigations, becoming a landmark in the history of science that is often referred to as the Copernican Revolution.

Among the great polymaths of the Renaissance, Copernicus was a mathematician, astronomer, jurist with a doctorate in law, physician, quadrilingual polyglot, classics scholar, translator, artist,^[3] Catholic cleric, governor, diplomat and economist.

Life[link]

Thorn birthplace (ul. Kopernika 15, left). Together with the house at no. 17 (right), it forms the Muzeum Mikołaja Kopernika.

Nicolaus Copernicus was born on 19 February 1473 in the city of Thorn, in the province of Royal Prussia, in the Crown of the Kingdom of Poland.^[4][5]

His father was a merchant from Kraków and his mother was the daughter of a wealthy Thorn merchant. Nicolaus was the youngest of four children. His brother Andreas (Andrew) became an Augustinian canon at Frauenburg (Frombork). His sister Barbara, named after her mother, became a Benedictine nun and, in her final years (she died after 1517), prioress of a convent in Culm (Kulm) (Chełmno). His sister Katharina married the businessman and Thorn city councilor Barthel Gertner and left five children, whom Copernicus looked after to the end of his life.^[6]

Copernicus never married or had children.

"Towards the close of 1542, he was seized with apoplexy and paralysis." He died on 24 May 1543, on the day that he was presented with an advance copy of his De revolutionibus orbium coelestium.^[7]

Father's family[link]

The father’s family can be traced to a village in Silesia near Neiße (Nysa). The village's name has been variously spelled Kopernik,^[8] Köppernig, Köppernick, and today Koperniki. In the 14th century, members of the family began moving to various other Silesian cities, to the Polish capital, Kraków (Cracow, 1367), and to Thorn (1400). The father, likely the son of Jan, came from the Kraków line.^[9]

Nicolaus was named after his father, who appears in records for the first time as a well-to-do merchant who dealt in copper, selling it mostly in Danzig (Gdańsk).^[10][11] He moved from Kraków to Thorn around 1458.^[12] Thorn, situated on the Vistula River, was at that time embroiled in the Thirteen Years' War (1454–66), in which the Kingdom of Poland and the Prussian Confederation, an alliance of Prussian cities, gentry and clergy, fought the Teutonic Order over control of the region. In this war Hanseatic cities like Danzig and Thorn, the hometown of Nicolaus Copernicus, chose to support the Polish king, who promised to respect the cities' traditional vast independence, which the Teutonic Order had challenged. The father of Nicolaus was actively engaged in the politics of the day, and supported Poland and the cities against the Teutonic Order.^[13] In 1454 he mediated negotiations between Poland’s Cardinal Zbigniew Oleśnicki and the Prussian cities for repayment of war loans. In the Second Peace of Thorn (1466), the Teutonic Order formally relinquished all claims to its western provinces, which as Royal Prussia remained a region of Poland for the next 300 years.

The father married Barbara Watzenrode, the astronomer's mother, between 1461 and 1464. He died sometime between 1483 and 1485. Upon the father’s death, young Nicolaus’ maternal uncle, Lucas Watzenrode the Younger (1447–1512), took the boy under his protection and saw to his education and career.

Mother's family[link]

Copernicus' maternal uncle, Lucas Watzenrode the Younger

Nicolaus’ mother, Barbara Watzenrode, was the daughter of Lucas Watzenrode the Elder and his wife Katherine (née Modlibóg).^[14][15][16] Not much is known about her life, but she is believed to have died when Nicolaus was a small boy. The Watzenrodes had come from the Schweidnitz (Świdnica) region of Silesia and had settled in Thorn after 1360, becoming prominent members of the city’s patrician class.^[17] Through the Watzenrodes' extensive family relationships by marriage, they were related to wealthy families of Thorn, Danzig and Elbing (Elbląg), and to the prominent Czapski, Działyński, Konopacki and Kościelecki noble families.^[18] The Modlibógs (literally, in Polish, "Pray to God") were a prominent Roman Catholic Polish family who had been well known in Poland's history since 1271.^[16] Lucas and Katherine had three children: Lucas Watzenrode the Younger, who would become Copernicus' patron; Barbara, the astronomer's mother; and Christina, who in 1459 married the merchant and mayor of Thorn, Tiedeman von Allen.

Lucas Watzenrode the Elder was well regarded in Thorn as a devout man and honest merchant, and he was active politically. He was a decided opponent of the Teutonic Knights and an ally of Polish King Casimir IV Jagiellon.^[19] In 1453 he was the delegate from Thorn at the Graudenz (Grudziądz) conference that planned to ally the cities of the Prussian Confederation with Casimir IV in their subsequent war against the Teutonic Knights.^[6] During the Thirteen Years' War that ensued the following year, he actively supported the war effort with substantial monetary subsidies, with political activity in Thorn and Danzig, and by personally fighting in battles at Lessen (Łasin) and Marienburg (Malbork).^[20] He died in 1462.

Lucas Watzenrode the Younger, the astronomer's maternal uncle and patron, was educated at the University of Krakow (now Jagiellonian University) and at the universities of Cologne and Bologna. He was a bitter opponent of the Teutonic Order^[21][22] and its Grand Master, who once referred to Watzenrode as “the devil incarnate.”^[23] In 1489 Watzenrode was elected Bishop of Warmia (Ermeland, Ermland) against the preference of King Casimir IV, who had hoped to install his own son in that seat. As a result, Watzenrode quarreled with the king until Casimir IV’s death three years later.^[24] Watzenrode was then able to form close relations with three successive Polish monarchs: John I Albert, Alexander Jagiellon, and Sigismund I the Old. He was a friend and key advisor to each ruler, and his influence greatly strengthened the ties between Warmia and Poland proper.^[25][26] Watzenrode came to be considered the most powerful man in Warmia, and his wealth, connections and influence allowed him to secure Copernicus’ education and career as a canon at Frombork Cathedral.

Languages[link]

German-language letter from Copernicus to Duke Albert of Prussia, giving medical advice for George von Kunheim (1541)

Copernicus is postulated to have spoken Latin, German, and Polish with equal fluency. He also spoke Greek and Italian.^{[27][28][29][30]} The vast majority of Copernicus’ surviving works are in Latin, which in his lifetime was the language of academia in Europe. Latin was also the official language of the Roman Catholic Church and of Poland's royal court, and thus all of Copernicus’ correspondence with the Church and with Polish leaders was in Latin.

There survive a few documents written by Copernicus in German. Martin Carrier mentions this as a reason to consider Copernicus’ native language to have been German.^[31] Other arguments are that Copernicus was born in a predominantly German-speaking town and that, while studying law at Bologna in 1496, he signed into the German natio (Natio Germanorum)—a student organization which, according to its 1497 by-laws, was open to students of all kingdoms and states whose mother-tongue ("Muttersprache") was German.^[32] However, according to French philosopher Alexandre Koyre, this in itself does not imply that Copernicus considered himself German, since students from Prussia and Silesia were routinely placed in that category, which carried certain privileges that made it a natural choice for German-speaking students, regardless of their ethnicity or self-identification.^{[32][33][34][35][36][37]}

Name[link]

In Copernicus’ day, people were often called after the places where they lived. Like the Silesian village that inspired it, Copernicus’ surname has been spelled variously. Today the English-speaking world knows the astronomer principally by the Latinized name, "Nicolaus Copernicus."

The surname likely had something to do with the local Silesian copper-mining industry,^[38] though some scholars assert that it may have been inspired by the dill plant (in Polish, "koperek" or "kopernik") that grows wild in Silesia.^[39]

As was to be the case with William Shakespeare a century later,^[40] numerous spelling variants of the name are documented for the astronomer and his relatives. The name first appeared as a place name in Silesia in the 13th century, where it was spelled variously in Latin documents. Copernicus "was rather indifferent about orthography."^[41] During his childhood, the name of his father (and thus of the future astronomer) was recorded in Thorn as Niclas Koppernigk around 1480.^[42][43] At Kraków he signed his name "Nicolaus Nicolai de Torunia."^[15] At Bologna in 1496, he registered in the Matricula Nobilissimi Germanorum Collegii resp. Annales Clarissimae Nacionis Germanorum of the Natio Germanica Bononiae as Dominus Nicolaus Kopperlingk de Thorn – IX grosseti.^[44][45] At Padua, Copernicus signed his name "Nicolaus Copernik", later as "Coppernicus."^[41] He signed a self-portrait, a copy of which is now at Jagiellonian University, "N Copernic."^[46] The astronomer Latinized his name to Coppernicus, generally with two "p"s (in 23 of 31 documents studied),^[47] but later in life he used a single "p". On the title page of De revolutionibus, Rheticus published the name as (in the genitive, or possessive, case) "Nicolai Copernici".

Education[link]

Collegium Maius, Kraków

Nicolaus Copernicus Monument in Kraków

Copernicus' uncle Watzenrode maintained contacts with the leading intellectual figures in Poland and was a friend of the influential Italian-born humanist and Kraków courtier, Filippo Buonaccorsi.^[48] Watzenrode seems first to have sent young Copernicus to the St. John's School at Thorn where he himself had been a master. Later, according to Armitage (some scholars differ), the boy attended the Cathedral School at Leslau, up the Vistula River from Thorn, which prepared pupils for entrance to the University of Krakow, Watzenrode's alma mater in Poland's capital.^[49]

In the winter semester of 1491–92 Copernicus, as "Nicolaus Nicolai de Thuronia," matriculated together with his brother Andrew at the University of Krakow (now Jagiellonian University). Copernicus began his studies in the Department of Arts (from the fall of 1491, presumably until the summer or fall of 1495) in the heyday of the Kraków astronomical-mathematical school, acquiring the foundations for his subsequent mathematical achievements. According to a later but credible tradition (Jan Brożek), Copernicus was a pupil of Albert Brudzewski, who by then (from 1491) was a professor of Aristotelian philosophy but taught astronomy privately outside the university; Copernicus became familiar with Brożek's widely read commentary to Georg von Peuerbach's Theoricæ novæ planetarum and almost certainly attended the lectures of Bernard of Biskupie and Wojciech Krypa of Szamotuły and probably other astronomical lectures by Jan of Głogów, Michael of Wrocław, Wojciech of Pniewy and Marcin Bylica of Olkusz.^[50]

Copernicus' Kraków studies gave him a thorough grounding in the mathematical-astronomical knowledge taught at the university (arithmetic, geometry, geometric optics, cosmography, theoretical and computational astronomy), a good knowledge of the philosophical and natural-science writings of Aristotle (De coelo, Metaphysics) and Averroes (which later would play an important role in shaping his theory), stimulated his interest in learning, and made him conversant with humanistic culture. Copernicus broadened the knowledge that he took from the university lecture halls with independent reading of books that he acquired during his Kraków years (Euclid, Haly Abenragel, the Alfonsine Tables, Johannes Regiomontanus' Tabulae directionum); to this period, probably, also date his earliest scientific notes, now preserved partly at Uppsala University.^[51] At Kraków Copernicus began collecting a large library on astronomy; it would later be carried off as war booty by the Swedes during the Deluge and is now at the Uppsala University Library.

Copernicus' four years at Kraków played an important role in the development of his critical faculties and initiated his analysis of the logical contradictions in the two most polular systems of astronomy—Aristotle's theory of homocentric spheres, and Ptolemy's mechanism of eccentrics and epicycles—the surmounting and discarding of which constituted the first step toward the creation of Copernicus' own doctrine of the structure of the universe.^[51]

Without taking a degree, probably in the fall of 1495, Copernicus left Kraków for the court of his uncle Watzenrode, who in 1489 had been elevated to Prince-Bishop of Warmia and soon (after November 1495) sought to place his nephew in a Warmia canonry vacated by 26 August 1495 death of its previous tenant. For unclear reasons—probably due to opposition from part of the chapter, who appealed to Rome—Copernicus' installation was delayed, inclining Watzenrode to send both his nephews to study law in Italy, seemingly with a view to furthering their ecclesiastic careers and thereby also strengthening his own influence in the Warmia chapter.^[51]

Leaving Warmia in mid-1496—possibly with the retinue of the chapter's chancellor, Jerzy Pranghe, who was going to Italy—in the fall (October?) of that year Copernicus arrived in Bologna and a few months later (after 6 January 1497) signed himself into the register of the Bologna University of Jurists' "German nation," which also included Polish youths from Silesia, Prussia and Pomerania as well as students of other nationalities.^[51]

It was only on 20 October 1497 that Copernicus, by proxy, formally succeeded to the Warmia canonry, which had been granted to him two years earlier. To this, by a document dated 10 January 1503 at Padua, he would add a sinecure at the Collegiate Church of the Holy Cross in Breslau (Wrocław), Silesia, Bohemia. Despite having received a papal indult on 29 November 1508 to receive further benefices, through his ecclesiastic career Copernicus not only did not acquire further prebends and higher stations (prelacies) at the chapter, but in 1538 he relinquished the Breslau sinecure. It is uncertain whether he was ordained a priest; he may only have taken minor orders, which sufficed for assuming a chapter canonry.^[51]

During his three-year stay at Bologna, between fall 1496 and spring 1501, Copernicus seems to have devoted himself less keenly to studying canon law (he received his doctorate in law only after seven years, following a second return to Italy in 1503) than to studying the humanities--probably attending lectures by Filippo Beroaldo, Antonio Urceo, called Codro, Giovanni Garzoni and Alessandro Achillini--and to studying astronomy. He met the famous astronomer Domenico Maria Novara da Ferrara and became his disciple and assistant. Copernicus was developing new ideas inspired by reading the "Epitome of the Almagest" (Epitome in Almagestum Ptolemei) by George von Peuerbach and Johannes Regiomontanus (Venice, 1496). He verified its observations about certain peculiarities in Ptolemy's theory of the Moon's motion, by conducting on 9 March 1497 at Bologna a memorable observation of Aldebaran, the brightest star in the Taurus constellation, whose results reinforced his doubts as to the geocentric system. Copernicus the humanist sought confirmation for his growing doubts through close reading of Greek and Latin authors (Pythagoras, Aristarchos of Samos, Cleomedes, Cicero, Pliny the Elder, Plutarch, Philolaus, Heraclides, Ecphantos, Plato), gathering, especially while at Padua, fragmentary historic information about ancient astronomical, cosmological and calendar systems.^[52]

Copernicus spent the jubilee year 1500 in Rome, where he arrived with his brother Andrew that spring, doubtless to perform an apprenticeship at the Papal Curia. Here, too, however, he continued his astronomical work begun at Bologna, observing, for example, a lunar eclipse on the night of 5–6 November 1500. According to a later account by Rheticus, Copernicus also—probably privately, rather than at the Roman Sapienza--as a "Professor Mathematum" (professor of astronomy) delivered, "to numerous... students and... leading masters of the science," public lectures devoted probably to a critique of the mathematical solutions of contemporary astronomy.^[53]

On his return journey doubtless stopping briefly at Bologna, in mid-1501 Copernicus arrived back in Warmia. After on 28 July receiving from the chapter a two-year extension of leave in order to study medicine (since "he may in future be a useful medical advisor to our Reverend Superior [Bishop Lucas Watzenrode] and the gentlemen of the chapter"), in late summer or in the fall he returned again to Italy, probably accompanied by his brother Andrew and by Canon B. Sculteti. This time he studied at the University of Padua, famous as a seat of medical learning, and—except for a brief visit to Ferrara in May–June 1503 to pass examinations for, and receive, his doctorate in canon law—he remained at Padua from fall 1501 to summer 1503.^[53]

Copernicus studied medicine probably under the direction of leading Padua professors—Bartolomeo da Montagnana, Girolamo Fracastoro, Gabriele Zerbi, Alessandro Benedetti—and read medical treatises that he acquired at this time, by Valescus de Taranta, Jan Mesue, Hugo Senensis, Jan Ketham, Arnold de Villa Nova, and Michele Savonarola, which would form the embryo of his later medical library.^[53]

One of the subjects that Copernicus must have studied was astrology, since it was considered an important part of a medical education.^[54] However, unlike most other prominent Renaissance astronomers, he appears never to have practiced or expressed any interest in astrology.^[55]

As at Bologna, Copernicus did not limit himself to his official studies. It was probably the Padua years that saw the beginning of his Hellenistic interests. He familiarized himself with Greek language and culture with the aid of Theodorus Gaza's grammar (1495) and J.B. Chrestonius' dictionary (1499), expanding his studies of antiquity, begun at Bologna, to the writings of Bessarion, J. Valla and others. There also seems to be evidence that it was during his Padua stay that there finally crystallized the idea of basing a new system of the world on the movement of the Earth.^[53]

As the time approached for Copernicus to return home, in spring 1503 he journeyed to Ferrara where, on 31 May 1503, having passed the obligatory examinations, he was granted the degree of doctor of canon law. No doubt it was soon after (at latest, in fall 1503) that he left Italy for good to return to Warmia.^[53]

Work[link]

Astronomer Copernicus, or Conversations with God, by Matejko. In background: Frombork Cathedral.

Having completed all his studies in Italy, 30-year-old Copernicus returned to Warmia, where – apart from brief journeys to Kraków and to nearby Prussian cities (Thorn, Danzig, Elbing, Graudenz, Marienburg, Königsberg) – he would live out the remaining 40 years of his life.^[53]

The Prince-Bishopric of Warmia enjoyed substantial autonomy, with its own diet (parliament), army, monetary unit (the same as in the other parts of Royal Prussia) and treasury.^[56]

Copernicus was his uncle's secretary and physician from 1503 to 1510 (or perhaps till that uncle's death on 29 March 1512) and resided in the Bishop's castle at Heilsberg (Lidzbark Warmiński), where he began work on his heliocentric theory. In his official capacity, he took part in nearly all his uncle's political, ecclesiastic and administrative-economic duties. From the beginning of 1504, Copernicus accompanied Watzenrode to sessions of the Royal Prussian diet held at Marienburg and Elbing and, write Dobrzycki and Hajdukiewicz, "participated... in all the more important events in the complex diplomatic game that ambitious politician and statesman played in defense of the particular interests of Prussia and Warmia, between hostility to the [Teutonic] Order and loyalty to the [Polish] Crown."^[53]

Copernicus' translation of Theophylact Simocatta's Epistles. Cover shows coats-of-arms of (clockwise from top) Poland, Lithuania and Kraków.

In 1504–12 Copernicus made numerous journeys as part of his uncle's retinue—in 1504, to Thorn and Danzig, to a session of the Royal Prussian Council in the presence of Poland's King Alexander Jagiellon; to sessions of the Prussian diet at Marienburg (1506), Elbing (1507) and Stuhm (1512); and he may have attended a Posen session (1510) and the coronation of Poland's King Sigismund I the Old in Kraków (1507). Watzenrode's itinerary suggests that in spring 1509 Copernicus may have attended the Kraków sejm.^[53]

It was probably on the latter occasion, in Kraków, that Copernicus submitted for printing at Jan Haller's press his translation, from Greek to Latin, of a collection, by the 7th-century Byzantine historian Theophylact Simocatta, of 85 brief poems called Epistles, or letters, supposed to have passed between various characters in a Greek story. They are of three kinds—"moral," offering advice on how people should live; "pastoral," giving little pictures of shepherd life; and "amorous," comprising love poems. They are arranged to follow one another in a regular rotation of subjects. Copernicus had translated the Greek verses into Latin prose, and he now published his version as Theophilacti scolastici Simocati epistolae morales, rurales et amatoriae interpretatione latina, which he dedicated to his uncle in gratitude for all the benefits he had received from him. With this translation, Copernicus declared himself on the side of the humanists in the struggle over the question whether Greek literature should be revived.^[57] Copernicus' first poetic work was a Greek epigram, composed probably during a visit to Kraków, for Johannes Dantiscus' epithalamium for Barbara Zapolya's 1512 wedding to King Zygmunt I the Old.^[58]

Some time before 1514, Copernicus wrote an initial outline of his heliocentric theory known only from later transcripts, by the title (perhaps given to it by a copyist), Nicolai Copernici de hypothesibus motuum coelestium a se constitutis commentariolus—commonly referred to as the Commentariolus. It was a succinct theoretical description of the world's heliocentric mechanism, without mathematical apparatus, and differed in some important details of geometric construction from De revolutionibus; but it was already based on the same assumptions regarding Earth's triple motions. The Commentariolus, which Copernicus consciously saw as merely a first sketch for his planned book, was not intended for printed distribution. He made only a very few manuscript copies available to his closest acquaintances, including, it seems, several Kraków astronomers with whom he collaborated in 1515–30 in observing eclipses. Tycho Brahe would include a fragment from the Commentariolus in his own treatise, Astronomiae instauratae progymnasmata, published in Prague in 1602, based on a manuscript that he had received from the Bohemian physician and astronomer Tadeáš Hájek, a friend of Rheticus. The Commentariolus would appear complete in print for the first time only in 1878.^[58]

Copernicus' tower at Frauenburg, where he lived and worked; rebuilt recently

Frombork Cathedral mount and fortifications. In foreground: statue of Copernicus

In 1510 or 1512 Copernicus moved to Frauenburg, a town to the northwest at the Vistula Lagoon on the Baltic Sea coast. There, in April 1512, he participated in the election of Fabian of Lossainen as Prince-Bishop of Warmia. It was only in early June 1512 that the chapter gave Copernicus an "external curia"—a house outside the defensive walls of the cathedral mount. In 1514 he purchased the northwestern tower within the walls of the Frauenburg stronghold. He would maintain both these residences to the end of his life, despite the devastation of the chapter's buildings by a raid against Frauenburg carried out by the Teutonic Order in January 1520, during which Copernicus' astronomical instruments were probably destroyed. Copernicus conducted astronomical observations in 1513–16 presumably from his external curia; and in 1522–43, from an unidentified "small tower" (turricula), using primitive instruments modeled on ancient ones—the quadrant, triquetrum, armillary sphere. At Frauenburg Copernicus conducted over half of his more than 60 registered astronomical observations.^[58]

Having settled permanently at Frauenburg, where he would reside to the end of his life, with interruptions in 1516–19 and 1520–21, Copernicus found himself at the Warmia chapter's economic and administrative center, which was also one of Warmia's two chief centers of political life. In the difficult, politically complex situation of Warmia, threatened externally by the Teutonic Order's aggressions (attacks by Teutonic bands; the Polish-Teutonic War of 1519–21; Albrecht's plans to annex Warmia), internally subject to strong separatist pressures (the selection of the prince-bishops of Warmia; currency reform), he, together with part of the chapter, represented a program of strict cooperation with the Polish Crown and demonstrated in all his public activities (the defense of his country against the Order's plans of conquest; proposals to unify its monetary system with the Polish Crown's; support for Poland's interests in the Warmia dominion's ecclesiastic administration) that he was consciously a citizen of the Polish-Lithuanian Republic. Soon after the death of uncle Bishop Watzenrode, he participated in the signing of the Second Treaty of Piotrków Trybunalski (7 December 1512), governing the appointment of the Bishop of Warmia, declaring, despite opposition from part of the chapter, for loyal cooperation with the Polish Crown.^[58]

That same year (before 8 November 1512) Copernicus assumed responsibility, as magister pistoriae, for administering the chapter's economic enterprises (he would hold this office again in 1530), having already since 1511 fulfilled the duties of chancellor and visitor of the chapter's estates.^[58]

His administrative and economic dutes did not distract Copernicus, in 1512–15, from intensive observational activity. The results of his observations of Mars and Saturn in this period, and especially a series of four observations of the Sun made in 1515, led to discovery of the variability of Earth's eccentricity and of the movement of the solar apogee in relation to the fixed stars, which in 1515–19 prompted his first revisions of certain assumptions of his system. Some of the observations that he made in this period may have had a connection with a proposed reform of the Julian calendar made in the first half of 1513 at the request of the Bishop of Fossombrone, Paul of Middelburg. Their contacts in this matter in the period of the Fifth Lateran Council were later memorialized in a complimentary mention in Copernicus' dedicatory epistle in De revolutionibus orbium coelestium and in a treatise by Paul of Middelburg, Secundum compendium correctionis Calendarii (1516), which mentions Copernicus among the learned men who had sent the Council proposals for the calendar's emendation.^[59]

Allenstein Castle

During 1516–21, Copernicus resided at Allenstein Castle as economic administrator of Warmia, including Allenstein (Olsztyn) and Mehlsack (Pieniężno). While there, he wrote a manuscript, Locationes mansorum desertorum (Locations of Deserted Fiefs), with a view to populating those fiefs with industrious farmers and so bolstering the economy of Warmia. When Allenstein was besieged by the Teutonic Knights during the Polish–Teutonic War (1519–21), Copernicus directed the defense of Allenstein and Warmia by Royal Polish forces. He also represented the Polish side in the ensuing peace negotiations.^[60]

Copernicus worked for years with the Royal Prussian diet, and with Duke Albert of Prussia (against whom Copernicus had defended Warmia in the Polish-Teutonic War), and advised King Sigismund, on monetary reform. He participated in discussions in the East Prussian diet about coinage reform in the Prussian countries; a question that concerned the diet was who had the right to mint coin. Political developments in Prussia culminated in the 1525 establishment of the Duchy of Prussia as a Protestant state in vassalage to Poland.

In 1526 Copernicus wrote a study on the value of money, Monetae cudendae ratio. In it he formulated an early iteration of the theory, now called Gresham's Law, that "bad" (debased) coinage drives "good" (un-debased) coinage out of circulation—70 years before Thomas Gresham. He also formulated a version of quantity theory of money. Copernicus' recommendations on monetary reform were widely read by leaders of both Prussia and Poland in their attempts to stabilize currency.^[61][62]

Thorvaldsen's Copernicus Monument in Warsaw

In 1533, Johann Widmanstetter, secretary to Pope Clement VII, explained Copernicus' heliocentric system to the Pope and two cardinals. The Pope was so pleased that he gave Widmanstetter a valuable gift.^[63] In 1535 Bernard Wapowski wrote a letter to a gentleman in Vienna, urging him to publish an enclosed almanac, which he claimed had been written by Copernicus. This is the first and only mention of a Copernicus almanac in the historical records. The "almanac" was likely Copernicus' tables of planetary positions. Wapowski's letter mentions Copernicus' theory about the motions of the earth. Nothing came of Wapowski's request, because he died a couple of weeks later.^[63]

Following the death of Prince-Bishop of Warmia Mauritius Ferber (1 July 1537), Copernicus participated in the election of his successor, Johannes Dantiscus (20 September 1537). Copernicus was one of four candidates for the post, written in at the initiative of Tiedemann Giese; but his candidacy was actually pro forma, since Dantiscus had earlier been named coadjutor bishop to Ferber.^[64] At first Copernicus maintained friendly relations with the new Prince-Bishop, assisting him medically in spring 1538 and accompanying him that summer on an inspection tour of Chapter holdings. But that autumn, their friendship was strained by suspicions over Copernicus' housekeeper, Anna Schilling, whom Dantiscus removed from Frauenburg in 1539.^[64]

Copernicus with medicinal plant

In his younger days, Copernicus the physician had treated his uncle, brother and other chapter members. In later years he was called upon to attend the elderly bishops who in turn occupied the see of Warmia—Mauritius Ferber and Johannes Dantiscus—and, in 1539, his old friend Tiedemann Giese, Bishop of Kulm (Chełmno). In treating such important patients, he sometimes sought consultations from other physicians, including the physician to Duke Albert and, by letter, the Polish Royal Physician.^[65]

"Nicolaus Copernicus Tornaeus Borussus Mathemat.", 1597

In the spring of 1541, Duke Albert summoned Copernicus to Königsberg to attend the Duke's counselor, George von Kunheim, who had fallen seriously ill, and for whom the Prussian doctors seemed unable to do anything. Copernicus went willingly; he had met von Kunheim during negotiations over reform of the coinage. And Copernicus had come to feel that Albert himself was not such a bad person; the two had many intellectual interests in common. The Chapter readily gave Copernicus permission to go, as it wished to remain on good terms with the Duke, despite his Lutheran faith. In about a month the patient recovered, and Copernicus returned to Frauenburg. For a time, he continued to receive reports on von Kunheim's condition, and to send him medical advice by letter.^[66]

Throughout this period of his life, Copernicus continued making astronomical observations and calculations, but only as his other responsibilities permitted and never in a professional capacity.

Some of Copernicus' close friends turned Protestant, but Copernicus never showed a tendency in that direction. The first attacks on him came from Protestants. Wilhelm Gnapheus, a Dutch refugee settled in Elbląg, wrote a comedy in Latin, Morosophus (The Foolish Sage), and staged it at the Latin school that he had established there. In the play, Copernicus was caricatured as a haughty, cold, aloof man who dabbled in astrology, considered himself inspired by God, and was rumored to have written a large work that was moldering in a chest.^[48]

Elsewhere Protestants were the first to react to news of Copernicus' theory. Melanchthon wrote:

Some people believe that it is excellent and correct to work out a thing as absurd as did that Sarmatian [i.e., Polish] astronomer who moves the earth and stops the sun. Indeed, wise rulers should have curbed such light-mindedness.^[48]

Nevertheless, in 1551, eight years after Copernicus' death, astronomer Erasmus Reinhold published, under the sponsorship of Copernicus' former military adversary, the Protestant Duke Albert, the Prussian Tables, a set of astronomical tables based on Copernicus' work. Astronomers and astrologers quickly adopted it in place of its predecessors.^[67]

Heliocentrism[link]

Mid-16th-century portrait^[68]

Some time before 1514 Copernicus made available to friends his "Commentariolus" ("Little Commentary"), a forty-page manuscript describing his ideas about the heliocentric hypothesis.^[69] It contained seven basic assumptions (detailed below).^[70] Thereafter he continued gathering data for a more detailed work.

About 1532 Copernicus had basically completed his work on the manuscript of De revolutionibus orbium coelestium; but despite urging by his closest friends, he resisted openly publishing his views, not wishing—as he confessed—to risk the scorn "to which he would expose himself on account of the novelty and incomprehensibility of his theses."^[64]

In 1533, Johann Albrecht Widmannstetter delivered a series of lectures in Rome outlining Copernicus' theory. Pope Clement VII and several Catholic cardinals heard the lectures and were interested in the theory. On 1 November 1536, Cardinal Nikolaus von Schönberg, Archbishop of Capua, wrote to Copernicus from Rome:

Some years ago word reached me concerning your proficiency, of which everybody constantly spoke. At that time I began to have a very high regard for you... For I had learned that you had not merely mastered the discoveries of the ancient astronomers uncommonly well but had also formulated a new cosmology. In it you maintain that the earth moves; that the sun occupies the lowest, and thus the central, place in the universe... Therefore with the utmost earnestness I entreat you, most learned sir, unless I inconvenience you, to communicate this discovery of yours to scholars, and at the earliest possible moment to send me your writings on the sphere of the universe together with the tables and whatever else you have that is relevant to this subject ...^[71]

By then Copernicus' work was nearing its definitive form, and rumors about his theory had reached educated people all over Europe. Despite urgings from many quarters, Copernicus delayed publication of his book, perhaps from fear of criticism—a fear delicately expressed in the subsequent dedication of his masterpiece to Pope Paul III. Scholars disagree on whether Copernicus' concern was limited to possible astronomical and philosophical objections, or whether he was also concerned about religious objections.^[72]

The book[link]

File:Nicolai Copernici torinensis De revolutionibus orbium coelestium.djvu

Copernicus was still working on De revolutionibus orbium coelestium (even if not certain that he wanted to publish it) when in 1539 Georg Joachim Rheticus, a Wittenberg mathematician, arrived in Frauenburg. Philipp Melanchthon, a close theological ally of Martin Luther, had arranged for Rheticus to visit several astronomers and study with them.

Rheticus became Copernicus' pupil, staying with him for two years and writing a book, Narratio prima (First Account), outlining the essence of Copernicus' theory. In 1542 Rheticus published a treatise on trigonometry by Copernicus (later included in the second book of De revolutionibus).

Under strong pressure from Rheticus, and having seen the favorable first general reception of his work, Copernicus finally agreed to give De revolutionibus to his close friend, Tiedemann Giese, bishop of Kulm, to be delivered to Rheticus for printing by the German printer Johannes Petreius at Nuremberg (Nürnberg), Germany. While Rheticus initially supervised the printing, he had to leave Nuremberg before it was completed, and he handed over the task of supervising the rest of the printing to a Lutheran theologian, Andreas Osiander.^[73]

Osiander added an unauthorised and unsigned preface, defending the work against those who might be offended by the novel hypotheses. He explained that astronomers may find different causes for observed motions, and choose whatever is easier to grasp. As long as a hypothesis allows reliable computation, it does not have to match what a philosopher might seek as the truth.

Death[link]

1735 epitaph, Frombork Cathedral. A 1580 epitaph had been destroyed.

Casket with Copernicus' remains, St. James' Cathedral Basilica, Allenstein, March 2010

Frombork Cathedral

Copernicus' 2010 grave, Frauenburg Cathedral

Copernicus died in Frauenburg on 24 May 1543. Legend has it that the first printed copy of De revolutionibus was placed in his hands on the very day that he died, allowing him to take farewell of his life's work. He is reputed to have awoken from a stroke-induced coma, looked at his book, and then died peacefully.

Copernicus was reportedly buried in Frombork Cathedral, where archaeologists for over two centuries searched in vain for his remains. Efforts to locate the remains in 1802, 1909, 1939 and 2004 had come to nought. In August 2005, however, a team led by Jerzy Gąssowski, head of an archaeology and anthropology institute in Pułtusk, after scanning beneath the cathedral floor, discovered what they believed to be Copernicus' remains.^[74]

The find came after a year of searching, and the discovery was announced only after further research, on 3 November 2008. Gąssowski said he was "almost 100 percent sure it is Copernicus."^{[citation needed]} Forensic expert Capt. Dariusz Zajdel of the Polish Police Central Forensic Laboratory used the skull to reconstruct a face that closely resembled the features—including a broken nose and a scar above the left eye—on a Copernicus self-portrait.^{[citation needed]} The expert also determined that the skull belonged to a man who had died around age 70—Copernicus' age at the time of his death.^[74]

The grave was in poor condition, and not all the remains of the skeleton were found; missing, among other things, was the lower jaw.^[75] The DNA from the bones found in the grave matched hair samples taken from a book owned by Copernicus which was kept at the library of the University of Uppsala in Sweden.^[76][77]

On 22 May 2010 Copernicus was given a second funeral in a Mass led by Józef Kowalczyk, the former papal nuncio to Poland and newly named Primate of Poland. Copernicus' remains were reburied in the same spot in Frombork Cathedral where part of his skull and other bones had been found. A black granite tombstone now identifies him as the founder of the heliocentric theory and also a church canon. The tombstone bears a representation of Copernicus' model of the solar system—a golden sun encircled by six of the planets.^[78]

Copernican system[link]

Predecessors[link]

Philolaus (c. 480–385 BCE) described an astronomical system in which a Central Fire (different from the Sun) occupied the centre of the universe, and a counter-Earth, the Earth, Moon, the Sun itself, planets, and stars all revolved around it, in that order outward from the centre.^[79] Heraclides Ponticus (387–312 BCE) proposed that the Earth rotates on its axis.^[80] Aristarchus of Samos (310 BCE – c. 230 BCE) identified the "central fire" with the Sun, around which he had the Earth orbiting.^[81] Some technical details of Copernicus's system^[82] closely resembled those developed earlier by the Islamic astronomers Naṣīr al-Dīn al-Ṭūsī and Ibn al-Shāṭir, both of whom retained a geocentric model.