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Aristarchus of Samos
Aristarchus of Samos
(/ˌærəˈstɑːrkəs/; Greek: Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios; c. 310 – c. 230 BC) was an ancient Greek astronomer and mathematician who presented the first known model that placed the Sun
at the center of the known universe with the Earth
revolving around it (see Solar system). He was influenced by Philolaus
of Croton, but Aristarchus identified the "central fire" with the Sun, and he put the other planets in their correct order of distance around the Sun.[1] Like Anaxagoras
before him, he suspected that the stars were just other bodies like the Sun, albeit further away from Earth. He was also the first one to deduce the rotation of earth on its axis. His astronomical ideas were often rejected in favor of the incorrect geocentric theories of Aristotle
and Ptolemy. Nicolaus Copernicus attributed the heliocentric theory to Aristarchus.[2]


1 Heliocentrism 2 Distance to the Sun
(lunar dichotomy) 3 See also 4 Notes 5 References 6 Further reading 7 External links

Heliocentrism[edit] See also: Heliocentrism The original text has been lost, but a reference in Archimedes's book The Sand Reckoner (Archimedis Syracusani Arenarius & Dimensio Circuli) describes a work by Aristarchus in which he advanced the heliocentric model as an alternative hypothesis to geocentrism. Thomas Heath gives the following English translation of Archimedes' text:[3]

You are now aware ['you' being King Gelon] that the "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 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 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

Aristarchus suspected the stars were other suns[4] that are very far away, and that in consequence there was no observable parallax, that is, a movement of the stars relative to each other as the Earth
moves around the Sun. Since stellar parallax is only detectable with telescopes, his accurate speculation was unprovable at the time. It is a common misconception that the heliocentric view was held as sacrilegious by the contemporaries of Aristarchus.[5] Lucio Russo traces this to Gilles Ménage's printing of a passage from Plutarch's On the Apparent Face in the Orb of the Moon. in which Aristarchus jokes with Cleanthes, who is head of the Stoics, a sun worshipper, and opposed to heliocentrism.[5] In the manuscript of Plutarch's text, Aristarchus says Cleanthes should be charged with impiety.[5] Ménage's version, published shortly after the trials of Galileo
and Giordano Bruno, transposes an accusative and nominative so that it is Aristarchus who is purported to be impious.[5] The resulting misconception of an isolated and persecuted Aristarchus is still transmitted today.[5][6] According to Plutarch, while Aristarchus postulated heliocentrism only as a hypothesis, Seleucus of Seleucia, a Hellenistic astronomer
Hellenistic astronomer
who lived a century after Aristarchus, maintained it as a definite opinion and gave a demonstration of it[7] but no full record has been found. In his Naturalis Historia, Pliny the Elder
Pliny the Elder
later wondered whether errors in the predictions about the heavens could be attributed to a displacement of the Earth
from its central position.[8] Pliny[9] and Seneca[10] referred to the retrograde motion of some planets as an apparent (and not real) phenomenon, which is an implication of heliocentrism rather than geocentrism. Still, no stellar parallax was observed, and Plato, Aristotle, and Ptolemy
preferred the geocentric model, which was held as true throughout the Middle Ages. The heliocentric theory was revived by Copernicus,[11] after which Johannes Kepler
Johannes Kepler
described planetary motions with greater accuracy with his three laws. Isaac Newton
Isaac Newton
later gave a theoretical explanation based on laws of gravitational attraction and dynamics. Distance to the Sun
(lunar dichotomy)[edit]

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

Main article: Aristarchus On the Sizes and Distances The only known surviving work usually attributed to Aristarchus, On the Sizes and Distances of the Sun
and Moon, is based on a geocentric world view. It has historically been read as stating that the angle subtended by the Sun's diameter is two degrees, but Archimedes
states in The Sand Reckoner that Aristarchus had a value of ½ degree, which is much closer to the actual average value of 32' or 0.53 degrees. The discrepancy may come from a misinterpretation of what unit of measure was meant by a certain Greek term in the text of Aristarchus.[12] Aristarchus claimed that at half moon (first or last quarter moon), the angle between the Sun
and Moon was 87°.[13] He might have proposed 87° as a lower bound, since gauging the lunar terminator's deviation from linearity to one degree of accuracy is beyond the unaided human ocular limit (with that limit being about three degrees of accuracy). Aristarchus is known to have also studied light and vision.[14] Using correct geometry, but the insufficiently accurate 87° datum, Aristarchus concluded that the Sun
was between 18 and 20 times farther away than the Moon.[15] (The true value of this angle is close to 89° 50', and the Sun's distance is actually about 400 times that of the Moon.) The implicit false solar parallax of slightly under three degrees was used by astronomers up to and including Tycho Brahe, c. AD 1600. Aristarchus pointed out that the Moon and Sun have nearly equal apparent angular sizes, and therefore their diameters must be in proportion to their distances from Earth; thus, the diameter of the Sun
was calculated to be between 18 and 20 times the diameter of the Moon.[16] See also[edit]

Aristarchus's inequality


^ Draper, John William (2007) [1874]. "History of the Conflict Between Religion and Science". In Joshi, S. T. The Agnostic Reader. Prometheus. pp. 172–173. ISBN 978-1-59102-533-7.  ^ George Kish (1978). A Source Book in Geography. Harvard University Press. p. 51. ISBN 978-0-674-82270-2.  ^ Heath (1913), p. 302. The italics and parenthetical comments are as they appear in Heath's original. ^ Louis Strous. "Who discovered that the Sun
was a star?". solar-center.stanford.edu. Retrieved 2014-07-13.  ^ a b c d e Russo, Lucio (2013-12-01). The Forgotten Revolution: How Science Was Born in 300 BC and Why it Had to Be Reborn. Translated by Levy, Silvio. Springer Science & Business Media. p. 82, fn.106. ISBN 9783642189043. Retrieved 13 June 2017. ; Russo, Lucio; Medaglia, Silvio M. (1996). "Sulla presunta accusa di empietà ad Aristarco di Samo". Quaderni Urbinati di Cultura Classica (in Italian). Fabrizio Serra Editore. New Series, Vol. 53 (2): 113–121. JSTOR 20547344.  ^ Plutarch. "De facie quae in orbe lunae apparet, Section 6". Perseus Digital Library. Tufts University. Retrieved 13 June 2017.  ^ Plutarch, Platonicae quaestiones, VIII, i ^ Neugebauer, O. (1975). A History of Ancient Mathematical Astronomy. Studies in the History of Mathematics and Physical Sciences. 1. Springer-Verlag. pp. 697–698.  ^ Naturalis historia, II, 70 ^ Naturales quaestiones, VII, xxv, 6–7 ^ Joseph A. Angelo (14 May 2014). Encyclopedia of Space and Astronomy. Infobase Publishing. p. 153. ISBN 978-1-4381-1018-9.  ^ http://www.dioi.org/vols/we0.pdf ^ Greek Mathematical Works, Loeb Classical Library, Harvard University, 1939–1941, edited by Ivor Thomas, volume 2 (1941), pages 6–7 ^ Heath, 1913, pp. 299–300; Thomas, 1942, pp. 2–3. ^ A video on reconstruction of Aristarchus' method, in Turkish without subtitles. ^ Kragh, Helge (2007). Conceptions of cosmos: from myths to the accelerating universe: a history of cosmology. Oxford University Press. p. 26. ISBN 0-19-920916-2. 


Heath, Sir Thomas (1913). Aristarchus of Samos, the ancient Copernicus; a history of Greek astronomy to Aristarchus, together with Aristarchus's Treatise on the sizes and distances of the sun and moon : a new Greek text with translation and notes. London: Oxford University Press. 

Further reading[edit]

Gomez, A. G. (2013). Aristarchos of Samos, the Polymath. AuthorHouse. ISBN 9781496994233.  Stahl, William (1970). "Aristarchus of Samos". Dictionary of Scientific Biography. 1. New York: Charles Scribner's Sons. pp. 246–250. ISBN 0-684-10114-9. 

External links[edit]

Wikiquote has quotations related to: Aristarchus of Samos

Biography: JRASC, 75 (1981) 29 First estimate of the Moon's distance and First estimate of the Sun's distance from educational website From Stargazers to Starships Heath, T. L. (1913) Aristarchus of Samos, the Ancient Copernicus: A history of Greek astronomy to Aristarchus together with Aristarchus' treatise on the sizes and distances of the sun and moon, a new Greek text with translation and notes, Oxford, Clarendon Press (PDF). O'Connor, John J.; Robertson, Edmund F., "Aristarchus of Samos", MacTutor History of Mathematics archive, University of St Andrews . Online Galleries, History of Science Collections, University of Oklahoma Libraries High resolution images of works by Aristarchus of Samos in .jpg and .tiff format.

v t e

Ancient Greek astronomy


Aglaonice Agrippa Anaximander Andronicus Apollonius Aratus Aristarchus Aristyllus Attalus Autolycus Bion Callippus Cleomedes Cleostratus Conon Eratosthenes Euctemon Eudoxus Geminus Heraclides Hicetas Hipparchus Hippocrates of Chios Hypsicles Menelaus Meton Oenopides Philip of Opus Philolaus Posidonius Ptolemy Pytheas Seleucus Sosigenes of Alexandria Sosigenes the Peripatetic Strabo Thales Theodosius Theon of Alexandria Theon of Smyrna Timocharis


(Ptolemy) On Sizes and Distances
On Sizes and Distances
(Hipparchus) On the Sizes and Distances (Aristarchus) On the Heavens
On the Heavens


Antikythera mechanism Armillary sphere Astrolabe Dioptra Equatorial ring Gnomon Mural instrument Triquetrum


Callippic cycle Celestial spheres Circle of latitude Counter-Earth Deferent and epicycle Equant Geocentrism Heliocentrism Hipparchic cycle Metonic cycle Octaeteris Solstice Spherical Earth Sublunary sphere Zodiac


Babylonian astronomy Egyptian astronomy


Medieval European science Indian astronomy Medieval Islamic astronomy

v t e

Ancient Greek mathematics


Anaxagoras Anthemius Archytas Aristaeus the Elder Aristarchus Apollonius Archimedes Autolycus Bion Bryson Callippus Carpus Chrysippus Cleomedes Conon Ctesibius Democritus Dicaearchus Diocles Diophantus Dinostratus Dionysodorus Domninus Eratosthenes Eudemus Euclid Eudoxus Eutocius Geminus Heron Hipparchus Hippasus Hippias Hippocrates Hypatia Hypsicles Isidore of Miletus Leon Marinus Menaechmus Menelaus Metrodorus Nicomachus Nicomedes Nicoteles Oenopides Pappus Perseus Philolaus Philon Porphyry Posidonius Proclus Ptolemy Pythagoras Serenus Simplicius Sosigenes Sporus Thales Theaetetus Theano Theodorus Theodosius Theon of Alexandria Theon of Smyrna Thymaridas Xenocrates Zeno of Elea Zeno of Sidon Zenodorus


Almagest Archimedes
Palimpsest Arithmetica Conics (Apollonius) Elements (Euclid) On the Sizes and Distances (Aristarchus) On Sizes and Distances
On Sizes and Distances
(Hipparchus) On the Moving Sphere (Autolycus) The Sand Reckoner


Problem of Apollonius Squaring the circle Doubling the cube Angle trisection


Cyrene Library of Alexandria Platonic Academy

Timeline of Ancient Greek mathematicians

Authority control

WorldCat Identities VIAF: 79398695 LCCN: n82068128 ISNI: 0000 0001 1798 0082 GND: 118645