Editing Heliocentrism (section)

==Ancient and medieval astronomy==
While the [[sphericity of the Earth]] was widely recognized in [[Ancient Greek astronomy|Greco-Roman astronomy]] from at least the 4th century BC,<ref>{{cite book |last=Dicks |first=D.R. |title=Early Greek Astronomy to Aristotle |pages=[https://archive.org/details/earlygreekastron0000dick/page/68 68] |date=1970 |isbn=978-0-8014-0561-7 |publisher=Cornell University Press |location=Ithaca, N.Y. |url=https://archive.org/details/earlygreekastron0000dick/page/68 }}</ref> the Earth's [[Earth's rotation|daily rotation]] and [[Earth's orbit|yearly orbit around the Sun]] was never universally accepted until the [[Copernican Revolution]].

While a moving Earth was proposed at least from the 4th century BC in [[Pythagoreanism]], and a fully developed heliocentric model was developed by [[Aristarchus of Samos]] in the 3rd century BC, these ideas were not successful in replacing the view of a static spherical Earth, and from the 2nd century AD the predominant model, which would be inherited by medieval astronomy, was the [[Ptolemaic system|geocentric model]] described in [[Ptolemy]]'s ''[[Almagest]]''.

[[File:geoz wb en.svg|thumb|upright=1.2|The movements of the Moon, the planets, and the Sun around the static Earth in the Ptolemaic geocentric model (upper panel) in comparison to the orbits of the planets and the daily-rotating Earth around the Sun in the Copernican heliocentric model (lower panel). In both models, the Moon rotates around the Earth.]]

The Ptolemaic system was a sophisticated astronomical system that managed to calculate the positions for the planets to a fair degree of accuracy.<ref>{{cite book |title=Man and nature in the Renaissance |first1=Allen G. |last1=Debus |publisher=Cambridge University Press |year=1987 |isbn=978-0-521-29328-0 |page=76 |url=https://books.google.com/books?id=caJygwa-jiEC&pg=PA76}}</ref> Ptolemy himself, in his ''Almagest'', says that any model for describing the motions of the planets is merely a [[Mathematics|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.<ref>In Book 1 section 7 he admits that a model in which the Earth revolves with respect to the stars would be simpler but doesn't go as far as considering a heliocentric system.</ref> However, he rejected the idea of a [[Earth rotation|spinning Earth]] as absurd as he believed it would create huge winds. Within his [[Ptolemy#Astronomy|model]] the distances of the [[Moon]], [[Sun]], [[planet]]s and [[star]]s could be determined by treating orbits' [[Celestial spheres#Antiquity|celestial spheres]] as contiguous realities, which gave the stars' distance as less than 20 [[Astronomical Units]],<ref>Dennis Duke, [http://people.scs.fsu.edu/~dduke/ptolemy.html Ptolemy's Universe] {{Webarchive|url=https://web.archive.org/web/20120729211430/http://people.sc.fsu.edu/~dduke/ptolemy.html |date=July 29, 2012 }}</ref> a regression, since [[Aristarchus of Samos]]'s heliocentric scheme had centuries earlier [[#Classical antiquity|necessarily]] placed the stars at least two orders of magnitude more distant.

Problems with Ptolemy's system were well recognized in [[History of astronomy#Middle Ages|medieval astronomy]], and an increasing effort to criticize and improve it in the late medieval period eventually led to the [[Copernican heliocentrism]] developed in [[History of astronomy#Renaissance and Early Modern Europe|Renaissance astronomy]].

===Classical antiquity===
{{See also|Ancient Greek astronomy}}

====Pythagoreans====
The first non-geocentric model of the [[universe]] was proposed by the [[Pythagoreans|Pythagorean]] philosopher [[Philolaus]] (d. 390 BC), who taught that at the center of the universe was a "central fire", around which the [[Earth]], [[Sun]], [[Moon]] and [[planet]]s revolved in [[uniform circular motion]]. This system postulated the existence of a [[Counter-Earth]] [[Collinearity|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.<ref>Boyer, C. ''A History of Mathematics.'' Wiley, p. 54.</ref> Kepler gave an alternative explanation of the Pythagoreans' "central fire" as the Sun, "''as most sects purposely hid[e] their teachings''".<ref>{{cite book|first=Johannes |last=Kepler|title=Epitome of Copernican Astronomy |at=Book IV, Part 1.2|year=1618–1621}}</ref>

[[Heraclides Ponticus|Heraclides of Pontus]] (4th century BC) said that the [[Earth's rotation|rotation of the Earth]] explained the apparent daily motion of the celestial sphere. It used to be thought that he believed [[Mercury (planet)|Mercury]] and [[Venus]] to revolve around the Sun, which in turn (along with the other planets) revolves around the Earth.<ref>{{Citation| volume = 23| issue = 4| page = 233| last = Eastwood| first = B. S.| title = Heraclides and Heliocentrism – Texts Diagrams and Interpretations| journal=Journal for the History of Astronomy| date = November 1, 1992| bibcode = 1992JHA....23..233E| doi = 10.1177/002182869202300401| s2cid = 118643709}}</ref> [[Macrobius]] (AD 395{{mdash}}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]].<ref>{{citation|first=Otto E. |last=Neugebauer|title=A history of ancient mathematical astronomy|publisher=Springer|place=Berlin/Heidelberg/New York|year=1975|page=695|isbn=978-3-540-06995-9|author-link=Otto E. Neugebauer}}</ref><ref>{{citation|title=The astronomical system of Copernicus|last=Rufus|first=W. Carl|journal=[[Popular Astronomy (US magazine)|Popular Astronomy]]|volume=31|pages=511–512 [512]|bibcode=1923PA.....31..510R|year=1923}}</ref>

====Aristarchus of Samos====
[[File:Aristarchus working.jpg|thumb|right|[[Aristarchus of Samos|Aristarchus']] 3rd century BC calculations on the relative sizes of the Earth, Sun and Moon, from a 10th-century AD Greek copy]]

The first person known to have proposed a heliocentric system was [[Aristarchus of Samos]] {{nowrap|({{circa|270}} BC)}}. Like his contemporary [[Eratosthenes]], Aristarchus calculated the size of the Earth and measured the [[On the Sizes and Distances (Aristarchus)|sizes and distances of the Sun and Moon]]. From his estimates, he concluded that the Sun was six to seven times wider than the Earth, and thought that the larger object would have the most attractive force.

His writings on the heliocentric system are lost, but some information about them is known from a brief description by his contemporary, [[Archimedes]], and from scattered references by later writers. Archimedes' description of Aristarchus' theory is given in the former's book, ''[[The Sand Reckoner]]''. The entire description comprises just three sentences, which [[Thomas Little Heath|Thomas Heath]] translates as follows:<ref name=HeathSand>{{harvtxt|Heath|1913|p=[https://archive.org/stream/aristarchusofsam00heatuoft#page/302 302]}}. The italics and parenthetical comments are as they appear in Heath's original.</ref>
<!--- This is a verbatim quotation of Heath's text.  As such, it should preserve the spelling of such words as "centre", which he actually used.-->
{{blockquote|''You [King Gelon] are aware that "universe" is the name given by most astronomers to the sphere, the centre of which is the centre of the earth, while its radius is equal to the straight line between the centre of the sun and the centre of the earth.  This is the common account (τά γραφόμενα), as you have heard from astronomers.  But Aristarchus 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 the fixed stars, situated about the same centre 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 centre of the sphere bears to its surface.''|''The Sand Reckoner'' (''Arenarius'' I, 4–7){{r|HeathSand}}}}

[[Aristarchus of Samos|Aristarchus]] presumably took the stars to be very far away because he was aware that their [[parallax#Stellar parallax|parallax]]<ref>That is, an apparent movement of the stars relative to the [[celestial pole]]s and [[celestial equator|equator]], and to each other, caused by the Earth's revolution around the Sun.</ref> would otherwise be observed over the course of a year. The stars are in fact so far away that stellar parallax only became detectable when sufficiently powerful [[telescope]]s had been developed in the [[1838 in science#Astronomy|1830s]].

No references to Aristarchus' heliocentrism are known in any other writings from before the [[common era]]. The earliest of the handful of other ancient references occur in two passages from the writings of [[Plutarch]]. These mention one detail not stated explicitly in Archimedes' account<ref>Although it could obviously be reasonably inferred therefrom.</ref>—namely, that Aristarchus' theory had the Earth rotating on an axis. The first of these reference occurs in ''Concerning the Face Which Appears in the Orb of the Moon'':<ref>{{harvtxt|Heath|1913|p=[https://archive.org/stream/aristarchusofsam00heatuoft#page/304 304]}}. Most modern scholars share Heath's opinion that it is Cleanthes in this passage who is being held as having accused Aristarchus of impiety (see {{harvnb|Gent|Godwin|1883|p=[https://archive.org/stream/plutarchsmorals51883plut#page/240 240]}}; {{harvnb|Dreyer|1953|p=[https://archive.org/stream/historyofplaneta00dreyuoft#page/138/mode/1up 138]}}; {{harvnb|Prickard|1911|p=[https://archive.org/stream/plutarchonfacewh00plut#page/20/mode/1up 20]}}; Cherniss 1957, p. [https://archive.org/stream/moraliainfifteen12plutuoft#page/55 55]; for example). The manuscripts of Plutarch's ''Concerning the Face Which Appears in the Orb of the Moon'' that have come down to us are corrupted, however, and the traditional interpretation of the passage has been challenged by [[Lucio Russo]], who insists that it should be interpreted as having Aristarchus rhetorically suggest that ''Cleanthes'' was being impious for wanting to shift the ''Sun'' from its proper place at the center of the universe ({{harvnb|Russo|2013|p=[https://books.google.com/books?id=ld8lBAAAQBAJ&pg=PA82 82]}}; {{harvnb|Russo|Medaglia|1996|pp=113–117}}).</ref>

{{blockquote|''Only do not, my good fellow, enter an action against me for impiety in the style of [[Cleanthes]], who thought it was the duty of Greeks to indict Aristarchus of Samos on the charge of impiety for putting in motion the Hearth of the Universe, this being the effect of his attempt to save the phenomena by supposing the heaven to remain at rest and the earth to revolve in an oblique circle, while it rotates, at the same time, about its own axis.''|''Concerning the Face Which Appears in the Orb of the Moon'' (''De facie in orbe lunae'', c. 6, pp. 922 F – 923 A.) }}

Only scattered fragments of [[Cleanthes|Cleanthes']] writings have survived in quotations by other writers, but in ''[[Lives and Opinions of Eminent Philosophers]]'', [[Diogenes Laërtius]] lists ''A reply to Aristarchus'' (Πρὸς Ἀρίσταρχον) as one of Cleanthes' works,<ref>Diogenes Laërtius (1972, Bk 7, ch 5, p. [https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0258:book=7:chapter=5&highlight=aristarchus 281])</ref> and some scholars{{sfn|Edwards|1998|loc=p. [https://books.google.com/books?id=nS51_7qbEWsC&pg=PA68 68] and n. 104, p. [https://books.google.com/books?id=nS51_7qbEWsC&pg=PA455 455]|ps=, for instance.}} have suggested that this might have been where Cleanthes had accused Aristarchus of [[impiety]].

The second of the references by Plutarch is in his ''Platonic Questions'':{{sfn|Heath|1913|p=[https://archive.org/stream/aristarchusofsam00heatuoft#page/305 305]}}

{{blockquote|''Did Plato put the earth in motion, as he did the sun, the moon, and the five planets, which he called the instruments of time on account of their turnings, and was it necessary to conceive that the earth "which is globed about the axis stretched from pole to pole through the whole universe" was not represented as being held together and at rest, but as turning and revolving (στρεφομένην καὶ ἀνειλουμένην), as Aristarchus and [[Seleucus of Seleucia|Seleucus]] afterwards maintained that it did, the former stating this as only a hypothesis (ὑποτιθέμενος μόνον), the latter as a definite opinion (καὶ ἀποφαινόμενος)?''| ''Platonic Questions'' (''Platonicae Quaestiones'' viii. I, 1006 C)}}

The remaining references to Aristarchus' heliocentrism are extremely brief, and provide no more information beyond what can be gleaned from those already cited. Ones which mention Aristarchus explicitly by name occur in [[Aetius (philosopher)|Aëtius]]' ''Opinions of the Philosophers'', [[Sextus Empiricus]]' ''Against the Mathematicians'',{{sfn|Heath|1913|p=[https://archive.org/stream/aristarchusofsam00heatuoft#page/305 305]}} and an anonymous scholiast to Aristotle.{{sfn|Dreyer|1953|p=[https://archive.org/stream/historyofplaneta00dreyuoft#page/139/mode/1up 139]}} Another passage in Aëtius' ''Opinions of the Philosophers'' reports that Seleucus the astronomer had affirmed the Earth's motion, but does not mention Aristarchus.{{sfn|Heath|1913|p=[https://archive.org/stream/aristarchusofsam00heatuoft#page/305 305]}}

====Seleucus of Seleucia====
{{Main|Seleucus of Seleucia}}
Since [[Plutarch]] mentions the "followers of Aristarchus" in passing, it is likely that there were other astronomers in the [[Classical Greece|Classical period]] who also espoused heliocentrism, but whose work was lost.<ref>{{cite web |title=Plutarch, Platonicae quaestiones, Question VIII, section 1 |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A2008.01.0384%3Achapter%3D8%3Asection%3D1 |website=www.perseus.tufts.edu}}</ref> The only other astronomer from antiquity known by name who is known to have supported Aristarchus' heliocentric model was Seleucus of Seleucia (b. 190 BC), a [[Hellenistic civilization|Hellenistic]] astronomer who flourished a century after Aristarchus in the [[Seleucid Empire]].<ref>{{cite book |chapter=Seleucus of Seleucia (c. 190 BC–?) |title=The Encyclopedia of Astronomy and Astrophysics |editor1-last=Murdin |editor1-first=Paul |pages=3998|doi=10.1888/0333750888 |isbn=978-0-333-75088-9 | bibcode=2000eaa..bookE3998.|year=2000|citeseerx=10.1.1.255.9251}}</ref> Seleucus was a proponent of the heliocentric system of Aristarchus.<ref>{{cite web|url=http://www.ics.forth.gr/~vsiris/ancient_greeks/hellinistic_period.html|title=Index of Ancient Greek Philosophers-Scientists|website=Ics.forth.gr|archive-url=https://web.archive.org/web/20180127034924/http://users.ics.forth.gr/~vsiris/ancient_greeks/hellinistic_period.html|archive-date=January 27, 2018|access-date=20 November 2018|url-status=dead|df=mdy-all}}</ref> Seleucus may have proved the heliocentric theory by determining the constants of a [[geometry|geometric]] model for the heliocentric theory and developing methods to compute planetary positions using this model. He may have used early [[trigonometry|trigonometric]] methods that were available in his time, as he was a contemporary of [[Hipparchus]].<ref>{{Citation | last1 = Bartel | first1 =  B. L.| author-link = Bartel Leendert van der Waerden | year = 1987 | title = The Heliocentric System in Greek, Persian and Hindu Astronomy | journal=Annals of the New York Academy of Sciences | volume = 500 | issue = 1| pages = 525–545 [527–529] | doi = 10.1111/j.1749-6632.1987.tb37224.x | postscript = . | bibcode=1987NYASA.500..525V| s2cid = 222087224}}</ref> A fragment of a work by Seleucus has survived in Arabic translation, which was referred to by [[Abu Bakr al-Razi|Rhazes]] (b. 865).<ref>{{citation|title=Studies in Arabic versions of Greek texts and in mediaeval science|volume=2|first=Shlomo |last=Pines|publisher=[[Brill Publishers]]|year=1986|isbn=978-965-223-626-5|pages=viii & 201–217|author-link=Shlomo Pines}}</ref>

Alternatively, his explanation may have involved the phenomenon of [[tide]]s,<ref>[[Lucio Russo]], ''Flussi e riflussi'', Feltrinelli, Milano, 2003, {{ISBN|88-07-10349-4}}.</ref> which he supposedly theorized to be caused by the attraction to the Moon and by the revolution of the Earth around the Earth and Moon's [[Barycenter|center of mass]].

====Late antiquity====
There were occasional speculations about heliocentrism in Europe before Copernicus. In [[Carthage#Roman Carthage|Roman Carthage]], the [[pagan]] [[Martianus Capella]] (5th century AD) expressed the opinion that the planets Venus and Mercury did not go about the Earth but instead circled the Sun.<ref name=":0">[[William Harris Stahl|William Stahl]], trans., ''Martianus Capella and the Seven Liberal Arts'', vol. 2, ''The Marriage of Philology and Mercury'', 854, 857, New York: Columbia Univ. Pr, 1977, pp. 332–333</ref> Capella's model was discussed in the [[Early Middle Ages]] by various anonymous 9th-century commentators<ref name=":1">{{Citation | last = Eastwood | first = Bruce S. | title = Ordering the Heavens: Roman Astronomy and Cosmology in the Carolingian Renaissance | publisher=Brill | year = 2007 | location = Leiden | pages = 244–259 | isbn = 978-90-04-16186-3}}</ref> and Copernicus mentions him as an influence on his own work.<ref name=":2">{{Citation | last1 = Eastwood | first1 = Bruce S. | year = 1982 | title = Kepler as Historian of Science: Precursors of Copernican Heliocentrism according to ''De revolutionibus'' I, 10 | journal=Proceedings of the American Philosophical Society | volume = 126 | pages = 367–394 | postscript = . }}</ref> Also [[Macrobius]] (420 CE) described a heliocentric model.<ref name=":13">{{Cite journal |last=Carman |first=Christián C. |date=2017-12-23 |title=The first Copernican was Copernicus: the difference between Pre-Copernican and Copernican heliocentrism |url=http://dx.doi.org/10.1007/s00407-017-0198-3 |journal=Archive for History of Exact Sciences |volume=72 |issue=1 |pages=1–20 |doi=10.1007/s00407-017-0198-3 |issn=0003-9519|hdl=11336/72174 |hdl-access=free }}</ref>

===Ancient India===
{{See also|Indian astronomy}}
	
[[Aryabhata]] (476–550), in his [[magnum opus]] ''[[Aryabhatiya]]'' (499), propounded a planetary model in which the Earth was taken to be [[Earth's rotation|spinning on its axis]] and the periods of the planets were given with respect to the Sun.{{sfn|Thurston|1993|p=188}}<ref name=":13"/>  His immediate commentators, such as [[Lalla]], and other later authors, rejected his innovative view about the turning Earth.<ref>{{Cite book|title=Mathematics in India|title-link=Mathematics in India (book)|last=Plofker|first=Kim|publisher=Princeton University Press|year=2009|isbn=978-1-4008-3407-5|location=Princeton|pages=111–112|oclc=650305544}}</ref> It has been argued that Aryabhatta's calculations were based on an underlying heliocentric model, in which the planets orbit the Sun,<ref>The concept of Indian heliocentrism has been advocated by B. L. van der Waerden, ''Das heliozentrische System in der griechischen, persischen und indischen Astronomie.'' Naturforschenden Gesellschaft in Zürich. Zürich:Kommissionsverlag Leeman AG, 1970.</ref><ref>B.L. van der Waerden, "The Heliocentric System in Greek, Persian and Hindu Astronomy", in David A. King and George Saliba, ed., ''From Deferent to Equant: A Volume of Studies in the History of Science in the Ancient and Medieval Near East in Honor of E. S. Kennedy'', Annals of the New York Academy of Science, 500 (1987), pp. 529–534.</ref> although this has also been rebutted.<ref>Noel Swerdlow, "Review: A Lost Monument of Indian Astronomy," ''Isis'', 64 (1973): 239–243.</ref> The general consensus is that a synodic anomaly (depending on the position of the Sun) does not imply a physically heliocentric orbit (such corrections being also present in late Babylonian astronomical texts), and that Aryabhata's system was not explicitly heliocentric.<ref>{{cite book|last=Kim Plofker|title=Mathematics in India|title-link=Mathematics in India|publisher=Princeton University Press|location=Princeton, NJ|date=2009|page=[https://archive.org/details/mathematicsindia00plof/page/n125 111]|isbn=978-0-691-12067-6}}</ref> He also made many astronomical calculations, such as the times of the [[solar eclipse|solar]] and [[lunar eclipse|lunar]] [[eclipse]]s, and the instantaneous motion of the Moon.{{sfn|Joseph|2000|pp=393–394, 408}} Early followers of Aryabhata's model included [[Varahamihira]], [[Brahmagupta]], and [[Bhaskara II]].

===Medieval Islamic world===
{{See also|Astronomy in medieval Islam|Islamic cosmology}}
For a time, [[List of Muslim astronomers|Muslim astronomers]] accepted the [[Ptolemaic model|Ptolemaic system]] and the geocentric model, which were used by {{nowrap|[[al-Battani]]}} to show that the distance between the Sun and the Earth varies.{{sfn|Sabra|1998|pp=317f|ps=: {{blockquote|All Islamic astronomers from Thabit ibn Qurra in the ninth century to Ibn al-Shatir in the fourteenth, and all natural philosophers from al-Kindi to Averroes and later, are known to have accepted ... the Greek picture of the world as consisting of two spheres of which one, the celestial sphere ... concentrically envelops the other.}}}}<ref>{{cite web|url=https://www.famousscientists.org/al-battani/|title=Al-Battani|website=Famous Scientists|access-date=20 November 2018}}</ref> In the 10th century, {{nowrap|[[al-Sijzi]]}} accepted that the [[Earth's rotation|Earth rotates around its axis]].<ref>{{Cite journal|volume=108|issue=67|pages=762|last=Alessandro Bausani|title=Cosmology and Religion in Islam|journal=Scientia/Rivista di Scienza|year=1973}}</ref><ref name=young /> According to later astronomer [[al-Biruni]], al-Sijzi invented an [[astrolabe]] called ''al-zūraqī'' based on a belief held by some of his contemporaries that the apparent motion of the stars was due to the Earth's movement, and not that of the [[firmament]].<ref name=young>{{cite book|publisher=Cambridge University Press|isbn=978-0-521-02887-5|editor-last1=Young|editor-first1=M. J. L.|title=Religion, Learning and Science in the 'Abbasid Period|year=2006|page=[https://archive.org/stream/M.J.L.YoungJ.D.LathamR.B.SerjeantEdsReligionLearningAndScienceInTheAbbasidPeriod/M.%20J.%20L.%20Young%2C%20J.%20D.%20Latham%2C%20R.%20B.%20Serjeant%20eds%20Religion%2C%20Learning%20and%20Science%20in%20the%20%60Abbasid%20Period#page/n217/mode/1up 413]}}</ref><ref>{{cite book|publisher=SUNY Press|isbn=978-1-4384-1419-5|last=Nasr|first=Seyyed Hossein|title=An Introduction to Islamic Cosmological Doctrines|date= 1993|page=135}}</ref> Islamic astronomers began to criticize the Ptolemaic model, including [[Ibn al-Haytham]] in his ''{{nowrap|Al-Shukūk}} 'alā Baṭalamiyūs'' ("Doubts Concerning Ptolemy", c. 1028),<ref>{{cite book|publisher=Cambridge University Press|isbn=978-0-521-57600-0|last=Hoskin|first=Michael|title=The Cambridge Concise History of Astronomy|date= 1999|page=60}}</ref>{{sfn|Qadir|1989|pp=5–10.}} who found contradictions in Ptolemy's model, but al-Haytham remained committed to a geocentric model.<ref>[http://setis.library.usyd.edu.au/stanford/entries/copernicus/index.html Nicolaus Copernicus], [[Stanford Encyclopedia of Philosophy]] (2004).</ref>

[[File:Lunar phases al-Biruni.jpg|thumb|An illustration from [[al-Biruni]]'s astronomical works explains the different [[Lunar phase|phases of the Moon]] with respect to the position of the Sun.]]
Al-Biruni discussed the possibility of whether the Earth rotated about its own axis and orbited the Sun, but in his ''Masudic Canon'' (1031),<ref name="Covington 2007">{{cite web|last=Covington|first=Richard|title=Rediscovering Arabic Science|url=http://archive.aramcoworld.com/issue/200703/rediscovering.arabic.science.htm|website=Aramco World|access-date=20 November 2018}}</ref> he expressed his faith in a geocentric and stationary Earth.<ref>E. S. Kennedy, "Al-Bīrūnī's Masudic Canon", ''Al-Abhath'', 24 (1971): 59–81; reprinted in David A. King and Mary Helen Kennedy, ed., ''Studies in the Islamic Exact Sciences,'' Beirut, 1983, pp. 573–595.</ref> He was aware that if the Earth rotated on its axis, it would be consistent with his astronomical observations,<ref>G. Wiet, V. Elisseeff, P. Wolff, J. Naudu (1975). ''History of Mankind, Vol 3: The Great medieval Civilisations'', p. 649. George Allen & Unwin Ltd, [[UNESCO]].</ref> but considered it a problem of [[natural philosophy]] rather than one of mathematics.<ref name=young />{{sfn|Saliba|1999}}

In the 12th century, non-heliocentric alternatives to the Ptolemaic system were developed by some Islamic astronomers, such as [[Nur ad-Din al-Bitruji]], who considered the Ptolemaic model mathematical, and not physical.<ref>{{cite encyclopedia|editor=Thomas Hockey|last=Samsó|first=Julio|title=Biṭrūjī: Nūr al-Dīn Abū Isḥāq &#91;Abū Jaʿfar&#93; Ibrāhīm ibn Yūsuf al-Biṭrūjī|encyclopedia=The Biographical Encyclopedia of Astronomers|publisher=Springer|year=2007|location=New York|pages=133–134|url=http://islamsci.mcgill.ca/RASI/BEA/Bitruji_BEA.htm|isbn=978-0-387-31022-0|display-editors=etal}} ([http://islamsci.mcgill.ca/RASI/BEA/Bitruji_BEA.pdf PDF version])</ref><ref name=DSB /> His system spread throughout most of Europe in the 13th century, with debates and refutations of his ideas continued to the 16th century.<ref name=DSB>{{cite encyclopedia|last=Samsó|first=Julio|title=Al-Bitruji Al-Ishbili, Abu Ishaq|encyclopedia=[[Dictionary of Scientific Biography]]| publisher=Charles Scribner's Sons|location=New York|year=1970–80|isbn=978-0-684-10114-9|url=http://www.encyclopedia.com/doc/1G2-2830904829.html}}</ref>

The [[Maragheh observatory|Maragha]] school of astronomy in [[Ilkhanid]]-era Persia further developed "non-Ptolemaic" planetary models involving [[Earth's rotation]]. Notable astronomers of this school are [[Al-Urdi]] (d. 1266) [[Najm al-Dīn al-Qazwīnī al-Kātibī|Al-Katibi]] (d. 1277),<ref>''[https://archive.org/details/Hikmat3ayn Hikmat al-'Ain]'', p. 78</ref> and [[Nasir al-Din al-Tusi|Al-Tusi]] (d. 1274).

The arguments and evidence used resemble those used by Copernicus to support the Earth's motion.<ref name=Ragep>{{Citation |last=Ragep |first=F. Jamil |year=2001a |title=Tusi and Copernicus: The Earth's Motion in Context |journal=Science in Context |volume=14 |issue=1–2 |pages=145–163 |doi=10.1017/s0269889701000060|s2cid=145372613 }}</ref><ref name=Ragep2>{{Citation |last1=Ragep |first1=F. Jamil |year=2001b |title=Freeing Astronomy from Philosophy: An Aspect of Islamic Influence on Science |journal=Osiris |series=2nd Series |volume=16 |issue=Science in Theistic Contexts: Cognitive Dimensions |pages=49–64 & 66–71 |bibcode = 2001Osir...16...49R |doi=10.1086/649338 |last2=Al-Qushji |first2=Ali|s2cid=142586786 |url=http://digitool.library.mcgill.ca:80/R/?func=dbin-jump-full&object_id=156332 }}</ref>
The criticism of Ptolemy as developed by [[Averroes]] and by the Maragha school explicitly address the [[Earth's rotation]] but it did not arrive at explicit heliocentrism.<ref name="Huff 1993">{{cite book | last=Huff | first=Toby E. | title=The Rise of Early Modern Science: Islam, China and the West | publisher=Cambridge University Press | series=The Rise of Early Modern Science: Islam, China, and the West | year=2003 | isbn=978-0-521-52994-5 | url=https://books.google.com/books?id=DLxRGjr1gYQC}}</ref>
The observations of the Maragha school were further improved at the Timurid-era [[Ulugh Beg Observatory|Samarkand observatory]] under [[Ali Qushji|Qushji]] (1403–1474).

===Medieval India===
In [[India]], [[Nilakantha Somayaji]] (1444–1544), in his ''Aryabhatiyabhasya'', a commentary on Aryabhata's ''Aryabhatiya'', developed a computational system for a geo-heliocentric planetary model, in which the planets orbit the Sun, which in turn orbits the Earth, similar to the [[Tychonic system|system later proposed]] by [[Tycho Brahe]]. In the ''[[Tantrasamgraha]]'' (1501), Somayaji 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 heliocentrism|Copernican models]],{{sfn|Joseph|2000}}<ref>{{cite journal|title=Model of planetary motion in the works of Kerala astronomers|last=Ramasubramanian|first=K.|journal=Bulletin of the Astronomical Society of India|volume=26|pages=11–31 [23–24]|bibcode=1998BASI...26...11R|year=1998}}</ref> but did not propose any specific models of the universe.{{sfn|Ramasubramanian|Srinivas|Sriram|1994|p=788}} Nilakantha's planetary system also incorporated the Earth's rotation on its axis.<ref>{{citation|first=Amartya Kumar |last=Dutta|title=Āryabhata and axial rotation of earth|journal=Resonance|issn=0973-712X|volume=11|issue=5|date=May 2006|doi=10.1007/BF02839373|pages=58–72 [70–71]|s2cid=118434268}}</ref> Most astronomers of the [[Kerala school of astronomy and mathematics]] seem to have accepted his planetary model.{{sfn|Joseph|2000|p=408}}<ref>{{cite journal | last1 = Ramasubramanian | first1 = K. | last2 = Srinivas | first2 = M. D. | last3 = Sriram | first3 = M. S. | year = 1994 | title = Modification of the earlier Indian planetary theory by the Kerala astronomers (c. 1500 AD) and the implied heliocentric picture of planetary motion | journal=[[Current Science]] | volume = 66 | pages = 784–790}}</ref>