Earlier theories

Main article: Heliocentrism

Much has been which did not, however, revolve around a central sun. Copernicus did not attribute his inspiration to Aristarchus as is sometimes stated. When Copernicus' book was published, it contained an unauthorized preface by the Lutheran theologian Andreas Osiander. This cleric stated that Copernicus wrote his heliocentric account of the earth's movement as a mere mathematical hypothesis, not as an account that contained truth or even probability. Since Copernicus' hypothesis was believed to contradict the Old Testament account of the sun's movement around the earth (Joshua 10:13), this was apparently written to soften any religious backlash against the book. However, there is no evidence that Copernicus himself considered the heliocentric model as merely mathematically convenient, separate from reality. Heliocentric Solar System Heliocentrism (lower panel) in comparison to the geocentric model (upper panel) In astronomy, heliocentrism is the theory that the sun is at the center of the Universe and/or the Solar System. ... Sol redirects here. ... For other uses of this name, including the grammarian Aristarchus of Samothrace, see Aristarchus Statue of Aristarchus at Aristotle University in Thessalonica, Greece Aristarchus (Greek: Ἀρίσταρχος; 310 BC - ca. ... Andreas Osiander (Andreas Hosemann) (1498 - 1552) was a German Protestant theologian. ... Topics in Christianity Movements · Denominations · Other religions Ecumenism · Preaching · Prayer Music · Liturgy · Calendar Symbols · Art · Criticism Important figures Apostle Paul · Church Fathers Constantine · Athanasius · Augustine Anselm · Aquinas · Palamas · Luther Calvin · Wesley Arius · Marcion of Sinope Archbishop of Canterbury · Catholic Pope Coptic Pope · Ecumenical Patriarch Christianity Portal This box:      Note: Judaism... The Book of Joshua is the sixth book in both the Hebrew Tanakh and the Old Testament of the Christian Bible. ...

It has been argued that in developing the mathematics of heliocentrism Copernicus drew on, not just the Greek, but also the work of Muslim astronomers, especially the works of Nasir al-Din Tusi (Tusi-couple), Mo'ayyeduddin Urdi (Urdi lemma) and Ibn al-Shatir. Copernicus also cited the theories of Albategni (Al-Battani), Ibn Battuta, Arzachel (Al-Zarkali) and Averroes (Ibn Rushd) as influences on his major work, while the works of Ibn al-Haytham and Abu-Rayhan Biruni was also known in Europe at the time. This is a sub-article of Islamic science and astronomy. ... Nasir Tusi Abu Jafar Muhammad Ibn Muhammad Ibn al-Hasan Nasir al-Din al-Tusi (1201–1274) was a Persian scientist, of Shia Islamic belief, born in Tus, Khorasan, Iran. ... The Tusi couple is a 2-cusped hypocycloid obtained by rolling a circle of radius inside a circle of radius . ... Mu’ayyad al-Din al-’Urdi was one of the astronomers of the Maragha observatory in Persia. ... Ibn al-Shatir (or Ibn ash-Shatir) (1304–1375) was a Muslim astronomer of Damascus. ... (c. ... It has been suggested that Travelling route of Ibn Batuta be merged into this article or section. ... For other meanings, see Arzachel (disambiguation) Al-Zarqali (in full Abu Ishaq Ibrahim ibn Yahya Al-Zarqali, Arzachel to Latin Europe), (1028–1087 CE), was a leading Arab mathematician and the foremost astronomer of his time. ... Ibn Rushd, known as Averroes (1126 – December 10, 1198), was an Andalusian-Arab philosopher and physician, a master of philosophy and Islamic law, mathematics, and medicine. ... (Arabic: أبو علي الحسن بن الحسن بن الهيثم, Latinized: Alhacen or (deprecated) Alhazen) (965 – 1039), was an Arab[1] Muslim polymath[2][3] who made significant contributions to the principles of optics, as well as to anatomy, astronomy, engineering, mathematics, medicine, ophthalmology, philosophy, physics, psychology, visual perception, and to science in general with his introduction of the... A statue of Biruni adorns the southwest entrance of Laleh Park in Tehran, Iran. ...

The Ptolemaic system

Main article: Geocentric model

The prevailing theory in Europe as Copernicus was writing was that created by Ptolemy in his Almagest, dating from about 150 A.D.. The Ptolemaic system drew on many previous theories that viewed Earth as a stationary center of the universe. Stars were embedded in a large outer sphere which rotated relatively rapidly, while the planets dwelt in smaller spheres between — a separate one for each planet. To account for apparent anomalies in this view, such as the retrograde motion of the planets, a system of deferents and epicycles was used. The planet revolved in a small circle (the epicycle) about a center which also revolved in a larger circle (the deferent) about a center on or near the Earth. This article is about the historical term. ... For other uses, see Europe (disambiguation). ... This article is about the geographer, mathematician and astronomer Ptolemy. ... Almagest is the Latin form of the Arabic name (al-kitabu-l-mijisti, i. ... The Roman army consists of 400,000 men. ... Mediaeval drawing of the Ptolemaic system. ... Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... The basic elements of Ptolemaic astronomy, showing a planet on an epicycle with a deferent and an equant. ... In the Ptolemaic system of astronomy, the epicycle (literally: on the cycle in Greek) was a geometric model to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. ...

A complementary theory to Ptolemy's employed homocentric spheres: the spheres within which the planets rotated, could themselves rotate somewhat. This theory predated Ptolemy (it was first devised by Eudoxus of Cnidus; by the time of Copernicus it was associated with Averroes). Also popular with astronomers were variations such as eccentrics — by which the rotational axis was offset and not completely at the center. Another article concerns Eudoxus of Cyzicus. ... Ibn Rushd, known as Averroes (1126 – December 10, 1198), was an Andalusian-Arab philosopher and physician, a master of philosophy and Islamic law, mathematics, and medicine. ... (This page refers to eccentricity in mathematics. ...

Ptolemy's unique contribution to this theory was the equant—a point about which the centre of a planet's epicycle moved with uniform angular velocity, but which was offset from the centre of its deferent. This violated one of the fundamental principles of Aristotelian cosmology—namely, that the motions of the planets should be explained in terms of uniform circular motion, and was considered a serious defect by many medieval astronomers. In Copernicus's day, the most up-to-date version of the Ptolemaic system was that of Peurbach (1423-1461) and Regiomontanus (1436-1476). Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ... Georg Purbach (also Peuerbach, Peurbach, Purbach, Purbachius) (May 30, 1423 – April 8, 1461) was an Austrian astronomer and mathematician. ... Johannes Müller von Königsberg (June 6, 1436 – July 6, 1476), known by his Latin pseudonym Regiomontanus, was an important German mathematician, astronomer and astrologer. ...

Copernican theory

Further information: Nicolaus Copernicus

Copernicus' major theory was published in the book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) during the year of his death, 1543, though he had arrived at his theory several decades earlier. Copernicus redirects here. ... Nicolai Copernici Torinensis De Revolutionibus Orbium Coelestium, Libri VI - On the Revolutions of the Heavenly Spheres, by Nicolaus Copernicus of Torin, Six Books (title page of 2nd edition, ex officina Henricpetrina Basel, 1566) Heliocentric model of the solar system De revolutionibus orbium coelestium (English: ), first printed in 1543 in Nuremberg... // Events February 21 - Battle of Wayna Daga - A combined army of Ethiopian and Portuguese troops defeat the armies of Adal led by Ahmed Gragn. ...

Statue of Copernicus next to Cracow University's Collegium Novum

The book marks the beginning of the shift away from a geocentric (and anthropocentric) universe with the Earth at its center. Copernicus held that the Earth is another planet revolving around the fixed sun once a year, and turning on its axis once a day. He arrived at the correct order of the known planets and explained the precession of the equinoxes correctly by a slow change in the position of the Earth's rotational axis. He also gave a clear account of the cause of the seasons: that the Earth's axis is not perpendicular to the plane of its orbit. He added another motion to the Earth, by which the axis is kept pointed throughout the year at the same place in the heavens; since Galileo Galilei, it has been recognized that for the Earth not to point to the same place would have been a motion. Download high resolution version (563x996, 264 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (563x996, 264 KB) Wikipedia does not have an article with this exact name. ... For several academies alternatively called Krakow Academy, see Education in Kraków The Jagiellonian University (Polish: , often shortened to UJ) is located in Kraków, Poland. ... The geocentric model (in Greek: geo = earth and centron = centre) of the universe is a paradigm which places the Earth at its center. ... Anthropocentrism (Greek άνθρωπος, anthropos, human, κέντρον, kentron, center), or the human-centered principle, refers to the idea that humanity must always remain the central concern for humans. ... This article is about the astronomical term. ... A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... The axis of rotation of a rotating body is a line such that the distance between any point on the line and any point of the body remains constant under the rotation. ... Look up day in Wiktionary, the free dictionary. ... Precession of the equinoxes refers to the precession of the Earths axis of rotation. ... Galileo redirects here. ...

Copernicus also replaced Ptolemy's equant circles with more epicycles. This is the main source of the statement that Copernicus' system had even more epicycles than Ptolemy's. With this change, Copernicus' system showed only uniform circular motions, correcting what he saw as the chief inelegance in Ptolemy's system. But while Copernicus put the Sun at the center of the celestial spheres, he did not put it at the exact centre of the universe, but near it. This article is about the geographer, mathematician and astronomer Ptolemy. ... Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ... In the Ptolemaic system of astronomy, the epicycle (literally: on the cycle in Greek) was a geometric model to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. ...

Copernicus' system was not experimentally better than Ptolemy's model. Copernicus was aware of this and could not present any observational "proof" in his manuscript, relying instead on arguments about what would be a more complete and elegant system. From publication until about 1700, few astronomers were convinced by the Copernican system, though the book was relatively widely circulated (around 500 copies of the first and second editions have survived,^[1] which is a large number by the scientific standards of the time). Many astronomers, however, accepted some aspects of the theory at the expense of others, and his model did have a large influence on later scientists such as Galileo and Johannes Kepler, who adopted, championed and (especially in Kepler's case) sought to improve it. Galileo's observation of the phases of Venus produced the first observational evidence for Copernicus' theory. Similarly, Galileo's observation of the moons of Jupiter proved that the solar system contained bodies that did not orbit Earth. Galileo redirects here. ... Kepler redirects here. ... In astronomy, a phase of the Moon is any of the aspects or appearances presented by the Moon as seen from Earth, determined by the portion of the Moon that is visibly illuminated by the Sun. ... (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ...

1660 engraving by an unknown author: Scenographia Systematis Copernicani

The Copernican system can be summarized in several propositions, as Copernicus himself did in his early Commentariolus that he handed only to friends probably in the 1510s. The "little commentary" was never printed or otherwise published, its existence was only known indirectly until a copy surfaced in Vienna in 1878. Image File history File links Size of this preview: 671 × 600 pixelsFull resolution‎ (783 × 700 pixels, file size: 449 KB, MIME type: image/jpeg) Faithful reproductions of two-dimensional original works cannot attract copyright in the U.S. according to the rule in Bridgeman Art Library v. ... Image File history File links Size of this preview: 671 × 600 pixelsFull resolution‎ (783 × 700 pixels, file size: 449 KB, MIME type: image/jpeg) Faithful reproductions of two-dimensional original works cannot attract copyright in the U.S. according to the rule in Bridgeman Art Library v. ... The Commentariolus (litte commentary) is a manuscript of Nicolaus Copernicus in which he outlines his revolutionary theory of the solar system. ... For other uses, see Vienna (disambiguation). ... 1878 (MDCCCLXXVIII) was a common year starting on Tuesday (see link for calendar). ...

The major parts of Copernican theory are:

1. Heavenly motions are uniform, eternal, and circular or compounded of several circles (epicycles).
2. The center of the universe is near the Sun.
3. Around the Sun, in order, are Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn, and the fixed stars.
4. The Earth has three motions: daily rotation, annual revolution, and annual tilting of its axis.
5. Retrograde motion of the planets is explained by the Earth's motion.
6. The distance from the Earth to the sun is small compared to the distance to the stars.

Whether these propositions were "revolutionary" or "conservative" was a topic of debate in the late twentieth century. Thomas Kuhn argued that Copernicus only transferred "some properties to the sun's many astronomical functions previously attributed to the earth." Other historians have since argued that Kuhn underestimated what was "revolutionary" about Copernicus' work, and emphasized the difficulty Copernicus would have had in putting forward a new astronomical theory relying alone on simplicity in geometry, given that he had no experimental evidence. Thomas Samuel Kuhn (July 18, 1922 – June 17, 1996) was an American intellectual who wrote extensively on the history of science and developed several important notions in the philosophy of science. ...

Arthur Koestler puts Copernicus in a different light to what many authors seem to suggest, portraying him as a coward who was reluctant to publish his work due to a crippling fear of ridicule. Arthur Koestler (September 5, 1905, Budapest – March 3, 1983, London) was a Hungarian polymath who became a naturalized British subject. ...

De revolutionibus orbium coelestium

Nicolai Copernicito Torinensis De Revolutionibus Orbium Coelestium, Libri VI (title page of 2nd edition, Basel, 1566).

Main article: De revolutionibus orbium coelestium Image File history File links De_revolutionibus_orbium_coeleftium. ... Image File history File links De_revolutionibus_orbium_coeleftium. ... Nicolai Copernici Torinensis De Revolutionibus Orbium Coelestium, Libri VI - On the Revolutions of the Heavenly Spheres, by Nicolaus Copernicus of Torin, Six Books (title page of 2nd edition, ex officina Henricpetrina Basel, 1566) Heliocentric model of the solar system De revolutionibus orbium coelestium (English: ), first printed in 1543 in Nuremberg...

Copernicus' major work, (Six books) On the Revolutions of the Heavenly Spheres (first edition 1543 in Nuremberg, second ed. 1566 in Basel), was the result of decades of labor. It opened with an originally anonymous preface by Andreas Osiander, a theologian friend of Copernicus, who urged that the theory, which was considered a tool that allows simpler and more accurate calculations, did not necessarily have implications outside the limited realm of astronomy. // Events February 21 - Battle of Wayna Daga - A combined army of Ethiopian and Portuguese troops defeat the armies of Adal led by Ahmed Gragn. ... Events January 7 - Pius V becomes Pope Selim II succeeds Suleiman I as Sultan of the Ottoman Empire Religious rioting in the Netherlands signifies the beginning of the Eighty Years War in the Netherlands. ... For other uses, see Basel (disambiguation). ... Andreas Osiander (Andreas Hosemann) (1498 - 1552) was a German Protestant theologian. ...

Copernicus' actual book began with a letter from his (by then deceased) friend Nikolaus Cardinal von Schönberg, the Archbishop of Capua, urging Copernicus to publish his theory. Then, in a lengthy introduction, Copernicus dedicated the book to Pope Paul III, explaining his ostensible motive in writing the book as relating to the inability of earlier astronomers to agree on an adequate theory of the planets, and noting that if his system increased the accuracy of astronomical predictions it would allow the Church to develop a more accurate calendar. At that time, a reform of the Julian Calendar was considered necessary and was one of the major reasons for Church funding of astronomy. Nikolaus Cardinal von Schönberg (born 11 August 1472 in Roth-Schönberg near Meissen, Saxony/Germany, died 7 September 1537 in Capua, Italy) was an Archbishop of Capua. ... Capua is a city in the province of Caserta, (Campania, Italy) situated 25 km (16 mi) north of Napoli, on the northeastern edge of the Campanian plain. ... In his 1543 book entitled, The Revolutions of the Heavenly Spheres, Nicolaus Copernicus outlined his mathematical exposition which revived the concept -- and more importantly confirmed -- that the Earth was not the center of the universe, but instead rotated around the Sun. ... Pope Paul III with his cardinal-nephew Alessandro Cardinal Farnese (left) and his other grandson (right), Ottavio Farnese, Duke of Parma Pope Paul III (February 29, 1468 – November 10, 1549), born Alessandro Farnese, was Pope of the Roman Catholic Church from 1534 to his death 1549. ... The Julian calendar was a reform of the Roman calendar which was introduced by Julius Caesar in 46 BC and came into force in 45 BC (709 ab urbe condita). ...

The work itself was then divided into six books:

1. General vision of the heliocentric theory, and a summarized exposition of his idea of the World
2. Mainly theoretical, presents the principles of spherical astronomy and a list of stars (as a basis for the arguments developed in the subsequent books)
3. Mainly dedicated to the apparent motions of the Sun and to related phenomena
4. Description of the Moon and its orbital motions
5. Concrete exposition of the new system
6. Concrete exposition of the new system (continued)

Acceptance of Copernican heliocentrism

The ideas presented by Copernicus were not markedly easier to use than the geocentric theory and did not produce more accurate predictions of planetary positions. They appeared to be contrary to common sense and to contradict the Bible. They did (with hindsight) accurately predict the relative distances of the planets from the Sun, but this meant abandoning the cherished Aristotelian idea that there is no empty space between the planetary spheres. Why then were Copernicus's ideas taken up by other astronomers? The key attraction was that Copernicus reintroduced the idea of uniform circular motion for the planets

During the 17th century, three further discoveries eventually led to the complete acceptance of heliocentrism:

• Johannes Kepler introduced the idea that the orbits of the planets were elliptical rather than circular;
• Using the newly-invented telescope, Galileo discovered the four large moons of Jupiter, the phases of Venus and the rotation of the Sun about a fixed axis^[2] as indicated by the apparent annual variation in the motion of sunspots.
• Isaac Newton proposed universal gravity and the inverse-square law of gravitational attraction to explain Kepler's elliptical planetary orbits.

Kepler redirects here. ... This article does not cite any references or sources. ... Galileo can refer to: Galileo Galilei, astronomer, philosopher, and physicist (1564 - 1642) the Galileo spacecraft, a NASA space probe that visited Jupiter and its moons the Galileo positioning system Life of Galileo, a play by Bertolt Brecht Galileo (1975) - screen adaptation of the play Life of Galileo by Bertolt Brecht... Sir Isaac Newton FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ...

Notes

1. ^ Gingerich (2004), p.248
2. ^ Fixed, that is, in the Copernican system. In a geostatic system the apparent annual variation in the motion of sunspots could only be explained as the result of an implausibly complicated precession of the Sun's axis of rotation (Linton, 2004, p.212; Sharratt, 1996, p.166; Drake, 1970, pp.191–196)

Bibliography

• Drake, Stillman (1970). Galileo Studies. Ann Arbor: The University of Michigan Press. ISBN 0-472-08283-3. 
• Gingerich, Owen (2004). The Book Nobody Read. London: William Heinemann. ISBN 0-434-01315-3. 
• Linton, Christopher M. (2004). From Eudoxus to Einstein—A History of Mathematical Astronomy. Cambridge: Cambridge University Press. ISBN 978-0-521-82750-8. 
• Sharratt, Michael (1996). Galileo: Decisive Innovator. Cambridge: Cambridge University Press. ISBN 0-521-56671-1. 

Further reading

• Hannam, James (2007). Deconstructing Copernicus. Medieval Science and Philosophy. Retrieved on 2007-08-17. Analyses the varieties of argument used by Copernicus in De revolutionibus.