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Encyclopedia > Geocentric model
Figure of the heavenly bodies - An illustration of the Ptolemaic geocentric system by Portuguese cosmographer and cartographer Bartolomeu Velho, 1568 (Bibliotèque National, Paris)
Figure of the heavenly bodies - An illustration of the Ptolemaic geocentric system by Portuguese cosmographer and cartographer Bartolomeu Velho, 1568 (Bibliotèque National, Paris)

In astronomy, the geocentric model of the universe is the theory that the Earth is at the center of the universe and the Sun and other objects go around it. Belief in this system was common in ancient Greece. It was embraced by both Aristotle and Ptolemy, and most Greek philosophers assumed that the Sun, Moon, stars, and naked eye planets circle the Earth. Similar ideas were held in ancient China.[1] Modern geocentrism is a belief currently held by certain groups that the Earth is the center of the universe and does not move. ... Geocentric orbit refers to the orbit of any object orbiting the Earth, such as the Moon or artificial satellites. ... For other uses, see Astronomy (disambiguation). ... For other uses, see Universe (disambiguation). ... The word theory has a number of distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion. ... This article is about Earth as a planet. ... The term ancient Greece refers to the periods of Greek history in Classical Antiquity, lasting ca. ... For other uses, see Aristotle (disambiguation). ... This article is about the geographer, mathematician and astronomer Ptolemy. ... Wikipedia does not yet have an article with this exact name. ... Sol redirects here. ... This article is about Earths moon. ... This article is about the astronomical object. ... It has been suggested that Classical Planets be merged into this article or section. ... The Dunhuang map from the Tang Dynasty (North Polar region). ...


Two common observations were believed to support the idea that the Earth is in the center of the Universe. The first is that the stars (including the Sun and planets) appear to revolve around the Earth each day, with the stars circling around the pole and those stars nearer the equator rising and setting each day and circling back to their rising point.[2] The second is the common sense perception that the Earth is solid and stable; it is not moving but is at rest.


The geocentric model was usually combined with a spherical Earth by ancient Greek and medieval philosophers. It is not the same as the older flat Earth model implied in some mythology. The ancient Greeks also believed that the motions of the planets were circular and not elliptical, a view that was not challenged in western culture before the 17th century. Medieval artistic representation of a spherical Earth - with compartments representing earth, air, and water (c. ... For other uses, see Flat Earth (disambiguation). ... For other uses, see Mythology (disambiguation). ...


The geocentric model held sway into the early modern age; from the late 16th century onward it was gradually replaced by the heliocentric model of Copernicus, Galileo and Kepler. Today, geocentric cosmology survives as a literary element within alternate history science fiction. The early modern period is a term used by historians to refer to the period in Western Europe and its first colonies, between the Middle Ages and modern society. ... (15th century - 16th century - 17th century - more centuries) As a means of recording the passage of time, the 16th century was that century which lasted from 1501 to 1600. ... 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. ... Copernicus redirects here. ... Galileo redirects here. ... Kepler redirects here. ... Alternative history or alternate history can be: A History told from an alternative viewpoint, rather than from the view of imperialist, conqueror, or explorer. ... Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ...

Contents

Classical Greece

The geocentric model entered Greek astronomy and philosophy at an early point; it can be found in Pre-socratic philosophy. In the 6th century BC, Anaximander proposed a cosmology with the Earth shaped like a section of a pillar (a cylinder), held aloft at the center of everything. The Sun, Moon, and planets were holes in invisible wheels surrounding the Earth; through the holes, humans could see concealed fire. About the same time, the Pythagoreans thought that the Earth was a sphere (in accordance with observations of eclipses), but not at the center; they believed that it was in motion around an unseen fire. Later these views were combined, so most educated Greeks from the 4th century BC on thought that the Earth was a sphere at the center of the universe.[citation needed] A recreation of the famous Library of Alexandria Greek astronomy is the astronomy of those who spoke Greek in classical antiquity. ... The Pre-Socratic philosophers were active before Socrates or contemporaneously, but expounding knowledge developed earlier. ... This article is about the Pre-Socratic philosopher. ... The Pythagoreans were a Hellenic organization of astronomers, musicians, mathematicians, and philosophers who believed that all things are, essentially, numeric. ...


In the 5th century BC, two influential Greek philosophers wrote works based on the geocentric model. These were Plato and his student Aristotle. According to Plato, the Earth was a sphere, stationary at the center of the universe. The stars and planets were carried around the Earth on spheres or circles, arranged in the order (outwards from the center): Moon, Sun, Venus, Mercury, Mars, Jupiter, Saturn, fixed stars. In the "Myth of Er," a section of the Republic, Plato describes the cosmos as the Spindle of Necessity, attended by the Sirens and turned by the three Fates. Eudoxus of Cnidus, who worked with Plato, developed a less mythical, more mathematical explanation of the planets' motion based on Plato's dictum stating that all phenomena in the heavens can be explained with uniform circular motion. Aristotle elaborated on Eudoxus' system. In the fully developed Aristotelian system, the spherical Earth is at the center of the universe. All heavenly bodies are attached to 56 concentric spheres which rotate around the Earth. (The number is so high because several transparent spheres are needed for each planet.) The Moon is on the innermost sphere. Thus it touches the realm of Earth, which contaminates it, causing the dark spots (macula) and the ability to go through lunar phases. It is not perfect like the other heavenly bodies, which shine by their own light. For other uses, see Plato (disambiguation). ... For other uses, see Aristotle (disambiguation). ... The celestial spheres relate to Johannes Keplers work Harmonia Mundi in which he drew together theories from the world of music, architecture, planetary motion and astronomy and linked them together to form an idea of a harmony and cohesion underlying all world phenomena and ruled by a divine force. ... The Myth of Er is an analogy used in Platos Republic. ... Plato. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In Greek mythology, the Sirens or Seirenes (Greek Σειρῆνας) were sea nymphs who lived on an island called Sirenum scopuli which was surrounded by cliffs and rocks. ... In Greek mythology, the white-robed Moirae or Moerae (Greek Μοίραι – the Apportioners, often called the Fates) were the personifications of destiny (Roman equivalent: Parcae, sparing ones, or Fatae; also equivalent to the Germanic Norns). ... Another article concerns Eudoxus of Cyzicus. ... In common law legal terminology a dictum (plural dicta) is any statement that forms a part of the judgment of a court, in particular a court whose decisions have value as precedent under the doctrine of stare decisis. ... A phenomenon (plural: phenomena) is an observable event, especially something special (literally something that can be seen from the Greek word phainomenon = observable). ... Human eye cross-sectional view. ... 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. ...


Adherence to the geocentric model stemmed largely from several important observations. First of all, if the Earth did move, then one ought to be able to observe the shifting of the fixed stars due to parallax. In short, the shapes of the constellations should change considerably over the course of a year, or else the stars are so much further away than the Sun and the planets that this motion would be undetectable. Stellar parallax was not detected until the 19th century as the distances from the Earth to the stars made the effect extremely subtle, so the Greeks chose the simpler of the two explanations (either the Earth is not moving and so no effect exists, or the stars are so far away the effect was undetectable). The lack of any observable parallax was considered a fatal flaw of any non-geocentric theory. For other uses, see Parallax (disambiguation). ... This article is about the star grouping. ...


Another important influence observation was that Venus stays about the same brightness most of the time, implying that it is usually about the same distance from Earth, which is more consistent with geocentrism than heliocentrism. In reality, that is because the loss of light caused by its phases compensates for the increase in apparent size caused by its varying distance from Earth. Other objections included the idea, put forward by Aristotle, that the natural state of heavy objects like the Earth was at rest, and that some force was required to move them. It was also believed by some that the Earth's rotation on its axis would cause the air and objects in it (such as birds or clouds) to be left behind.


A major flaw in the Eudoxan and Aristotelian models based on concentric spheres was that they could not explain the changes in brightness of the planets caused by a change in distance.


Claudius Ptolemy

Although the basic tenets of Greek geocentrism were established by the time of Aristotle, the details of his system did not become standard. This honor was reserved for the Ptolemaic system, espoused by the Hellenistic astronomer Claudius Ptolemaeus in the 2nd century AD. His main astronomical book, the Almagest, was the culmination of centuries of work by Hellenic, Hellenistic and Babylonian astronomers; it was accepted for over a millennium as the correct cosmological model by European and Islamic astronomers. Because of its influence, the Ptolemaic system is sometimes considered identical with the geocentric model. Hellenization (or Hellenisation) is a term used to describe a cultural change in which something non-Greek becomes Greek (Hellenistic civilization). ... 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 term ancient Greece refers to the periods of Greek history in Classical Antiquity, lasting ca. ... The term Hellenistic (derived from Héllēn, the Greeks traditional self-described ethnic name) was established by the German historian Johann Gustav Droysen to refer to the spreading of Greek culture over the non-Greek people that were conquered by Alexander the Great. ... Babylonian astronomy refers to the astronomy that developed in Mesopotamia, the land between the rivers Tigris and Euphrates, where the ancient kingdoms of Sumer, Assyria, Babylonia and Chaldea were located. ... This is a sub-article of Islamic science and astronomy. ...


Ptolemy argued that the Earth was in the center of the universe from the simple observation that half the stars were above the horizon and half were below the horizon at any time, and the assumption that the stars were all at some modest distance from the center of the universe. If the Earth were substantially displaced from the center, this division into visible and invisible stars would not be equal.[3]

The basic elements of Ptolemaic astronomy, showing a planet on an epicycle with an eccentric deferent and an equant point.
The basic elements of Ptolemaic astronomy, showing a planet on an epicycle with an eccentric deferent and an equant point.

Image File history File links Ptolemaic_elements. ... Image File history File links Ptolemaic_elements. ... 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. ... Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ...

Ptolemaic system

In the Ptolemaic system, each planet is moved by five or more spheres: one sphere is its deferent. The deferent was a circle centered around a point halfway between the equant and the earth. Another sphere is the epicycle which is embedded in the deferent. The planet is embedded in the epicycle sphere. The deferent rotates around the Earth while the epicycle rotates within the deferent, causing the planet to move closer to and farther from Earth at different points in its orbit, and even to slow down, stop, and move backward (in retrograde motion). The epicycles of Venus and Mercury are always centered on a line between Earth and the Sun (Mercury being closer to Earth), which explains why they are always near it in the sky. The Ptolemaic order of spheres from Earth outward is: 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. ... Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ... This article is about retrograde motion. ...

  1. Moon
  2. Mercury
  3. Venus
  4. Sun
  5. Mars
  6. Jupiter
  7. Saturn
  8. Fixed Stars

The deferent-and-epicycle model had been used by Greek astronomers for centuries, as had the idea of the eccentric (a deferent which is slightly off-center from the Earth). In the illustration, the center of the deferent is not the Earth but X, making it eccentric (from the Latin ex- or e- meaning "from," and centrum meaning "center"). Unfortunately, the system that was available in Ptolemy's time did not quite match observations, even though it was considerably improved over Aristotle's system. Sometimes the size of a planet's retrograde loop (most notably that of Mars) would be smaller, and sometimes larger. This prompted him to come up with the idea of an equant. The equant was a point near the center of a planet's orbit which, if you were to stand there and watch, the center of the planet's epicycle would always appear to move at the same speed. Therefore, the planet actually moved at different speeds when the epicycle was at different points on its deferent. By using an equant, Ptolemy claimed to keep motion which was uniform and circular, but many people did not like it because they did not think it was true to Plato's dictum of "uniform circular motion." The resultant system which eventually came to be widely accepted in the west was an unwieldy one to modern eyes; each planet required an epicycle revolving on a deferent, offset by an equant which was different for each planet. But it predicted various celestial motions, including the beginnings and ends of retrograde motion, fairly well at the time it was developed. Latin was the language originally spoken in the region around Rome called Latium. ... For other uses, see Observation (disambiguation). ... Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ...

This drawing from an Icelandic manuscript dated around 1750 illustrates the geocentric model.
This drawing from an Icelandic manuscript dated around 1750 illustrates the geocentric model.

Download high resolution version (570x652, 151 KB)The geocentric world view. ... Download high resolution version (570x652, 151 KB)The geocentric world view. ...

Geocentrism and rival systems

Not all Greeks agreed with the geocentric model. The Pythagorean system has already been mentioned; some Pythagoreans believed the Earth to be one of several planets going around a central fire. Hicetas and Ecphantus, two Pythagoreans of the 5th century BC, and Heraclides Ponticus in the 4th century BC, believed that the Earth rotated on its axis but remained at the center of the universe. Such a system still qualifies as geocentric. It was revived in the Middle Ages by Jean Buridan. Heraclides Ponticus is also sometimes said to have proposed that both Venus and Mercury went around the Sun rather than Earth, but the evidence for this claim is not clear. Martianus Capella definitely put Mercury and Venus on epicycles around the Sun. Hicetas (around 400 BC – around 335 BC) was a Greek philosopher of the Pythagorean School. ... Ecphantus (Ecphantos) is a shadowy Greek pre-Socratic philosopher. ... Heraclides Ponticus (387 - 312 BCE), also known as Heraklides, was a Greek philosopher who lived and died at Heraclea, now Eregli, Turkey. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Jean Buridan, in Latin Joannes Buridanus (1300 - 1358) was a French priest who sowed the seeds of religious scepticism in Europe. ... Martianus Minneus Felix Capella was a writer of the late Latin period, whose career flourished some time during the 5th century, before the year 439. ...


Aristarchus of Samos was the most radical. He wrote a work, which has not survived, on heliocentrism, saying that the Sun was at the center of the universe, while the Earth and other planets revolved around it. His theory was not popular, and he had only one known follower, Seleucus of Seleucia. 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. ... Seleucus (or Seleukos) of Seleucia (born circa 190 BC - ?) was a Greek philosopher. ...


Copernican system

In 1543 the geocentric system met its first serious challenge with the publication of Copernicus's De revolutionibus orbium coelestium, which posited that the Earth and the other planets instead revolved around the Sun. The geocentric system was still held for many years afterwards, as at the time the Copernican system did not offer better predictions than the geocentric system, and it posed problems for both natural philosophy and scripture. Nicolaus Copernicus (in Latin; Polish Mikołaj Kopernik, German Nikolaus Kopernikus - February 19, 1473 – May 24, 1543) was a Polish astronomer, mathematician and economist who developed a heliocentric (Sun-centered) theory of the solar system in a form detailed enough to make it scientifically useful. ... 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... Natural philosophy or the philosophy of nature, known in Latin as philosophia naturalis, is a term applied to the objective study of nature and the physical universe that was regnant before the development of modern science. ...


With the invention of the telescope in 1609, observations made primarily by Galileo Galilei (such as that Jupiter has moons) called into question some of the tenets of geocentrism but did not seriously threaten it. This article does not cite any references or sources. ... Galileo redirects here. ... For other uses, see Jupiter (disambiguation). ...

Phases of Venus
Phases of Venus

In December 1610, Galileo Galilei used his telescope to observe that Venus showed all phases, just like the Moon. This observation was incompatible with the Ptolemaic system, but was a natural consequence of the heliocentric system. Image File history File links Phases-of-Venus. ... Image File history File links Phases-of-Venus. ... // Events January 7 - Galileo Galilei discovers the Galilean moons of Jupiter. ... Galileo redirects here. ... (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... The phases of Venus can be seen without a telescope by those with exeptionally acute eye-sight. ... Lunar phase refers to the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. ...


Ptolemy placed Venus's deferent and epicycle entirely inside the sphere of the Sun (between the Sun and Mercury), but this was arbitrary; he could just as easily have swapped Venus and Mercury and put them on the other side of the Sun, or made any other arrangement of Venus and Mercury, as long as they were always near a line running from the Earth through the Sun. In this case, if the Sun is the source of all the light, under the Ptolemaic system:

If Venus is between Earth and the Sun, the phase of Venus must always be crescent or all dark.
If Venus is beyond the Sun, the phase of Venus must always be gibbous or full.

But Galileo saw Venus at first small and full, and later large and crescent. This article does not cite any references or sources. ... 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. ...


Astronomers of this time period saw the result of this being unsalvageable for a Ptolemaic cosmology, if the results were accepted as true. As a result, later 17th century competition between astronomical cosmologies focused on variations of Tycho Brahe's Tychonic system (in which the Earth was still at the center of the universe, and around it revolved the Sun, but all other planets revolved around the Sun in one massive set of epicycles), or variations on the Copernican system. This article is about the astronomer. ... Tychonic system The Tychonic system (or Tychonian system) was an effort by Tycho Brahe to create a model of the solar system which would combine what he saw as the mathematical benefits of the Copernican system with the philosophical and physical benefits of the Ptolemaic system. ...


Gravitation: Newton and Einstein

Johannes Kepler, after analysing Tycho Brahe's observations, constructed his three laws in 1609 and 1619, based on a heliocentric view where the planets moves in elliptical paths. Using these laws, he was the first astronomer to successfully predict a transit of Venus (for the year 1631). Kepler redirects here. ... This article is about the astronomer. ... Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ... Elliptical may refer to: Ellipse: a shape and mathematical construct Elliptical trainer: an exercise machine This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... // Events February 5 - Roger Williams emigrates to Boston. ...


In 1687, Isaac Newton devised his law of universal gravitation, which introduced gravitation as the force that both kept the Earth and planets moving through the heavens and also kept the air from flying away, allowing scientists to quickly construct a plausible heliocentric model for the solar system. Events March 19 - The men under explorer Robert Cavelier de La Salle murder him while searching for the mouth of the Mississippi River. ... 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. ... It has been suggested that this article or section be merged into Gravity. ...


In 1838, astronomer Friedrich Wilhelm Bessel successfully measured the parallax of the star 61 Cygni, disproving Ptolemy's assertion that parallax motion did not exist. Friedrich Wilhelm Bessel (July 22, 1784 – March 17, 1846) was a German mathematician, astronomer, and systematizer of the Bessel functions (which, despite their name, were discovered by Daniel Bernoulli). ... For other uses, see Parallax (disambiguation). ... 61 Cygni is a star in the constellation Cygnus. ...


A geocentric frame is useful for many everyday activities and most laboratory experiments, but is a less felicitous choice for solar-system mechanics and space travel. While a heliocentric frame is most useful in those cases, galactic and extra-galactic astronomy is easier if the sun is treated as neither stationary nor the center of the universe, but rotating around the center of our galaxy. 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. ...


Geocentrism today

Main article: Modern geocentrism

Individuals of some religions interpret their scriptures literally as stating that the Earth is the physical center of the universe. This requires the Sun to revolve around the Earth instead of the other way around because if the Earth were moving it could not continuously be in the center of the universe. This is known as modern geocentrism. Astrologers, while they may not believe in geocentrism as a principle, still employ the geocentric model in their calculations.[citation needed] Modern geocentrism is a belief currently held by certain groups that the Earth is the center of the universe and does not move. ... Planets in astrology have a different meaning to the modern astronomical understanding of what a planet is. ...


The contemporary Association for Biblical Astronomy, led by physicist Dr. Gerardus Bouw, holds to a modified version of the model of Tycho Brahe, which they call geocentricity.


A study done by Dr. Jon D. Miller of Northwestern University, an expert in the public understanding of science and technology[4], found that today one adult American in five thinks the Sun revolves around the Earth.[5] Northwestern University (NU) is a selective private, nonsectarian, coeducational research university with campuses located in Evanston, Illinois and downtown Chicago, Illinois. ...


In planetariums

The geocentric (Ptolemaic) model of the solar system is still of interest to planetarium makers, as, for technical reasons, a Ptolemaic-type motion for the planet light apparatus has some advantages over a Copernican-type motion. The celestial sphere, used for teaching purposes and sometimes for navigation, is also still based on a geocentric system. For the song by Ai Otsuka, see Planetarium (song) // A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. ... The celestial sphere is divided by the celestial equator. ...


Science fiction

Alternate history science fiction has produced some literature of interest on the proposition that some alternate universes and Earths might indeed have laws of physics and cosmologies that are Ptolemaic and Aristotelian in design. This subcategory began with Philip Jose Farmer's short story, Sail On! Sail On! (1952), where Columbus has access to radio technology, and where his Spanish-financed exploratory and trade fleet sail off the edge of the (flat) world in his geocentric alternate universe in 1492, instead of discovering North America and South America. Alternative history or alternate history can be: A History told from an alternative viewpoint, rather than from the view of imperialist, conqueror, or explorer. ... Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ... Philip José Farmer (born January 26, 1918) is an American author, principally known for his science fiction and fantasy novels and short stories. ... This article is in need of attention. ... North American redirects here. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ...


Richard Garfinkle's Celestial Matters (1996) is set in a more elaborated geocentric cosmos, where Earth is divided by two contending factions, the Classical Greece-dominated Delian League and the (Chinese) Middle Kingdom, both of which are capable of flight within an alternate universe based on Ptolemaic astronomy, Aristotle's physics and Taoist thought. Unfortunately, both superpowers have been fighting a thousand-year war since the time of Alexander the Great. Richard Garfinkle (fl. ... Celestial Matters, by Richard Garfinkle, Published by Tor, 1996. ... Parthenon This article is on the term Classical Greece itself. ... Delian League (Athenian Empire), right before the Peloponnesian War in 431 BC. Corcyra was not part of the League The Delian League was an association of Greek city-states in the 5th century BC. It was led by Athens. ... The Middle Kingdom is: a old name for China a period in the History of Ancient Egypt, the Middle Kingdom of Egypt This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... This artistic representation of the geocentric model shows signs of the zodiac and the solar system with world at centre. ... For other uses, see Aristotle (disambiguation). ... For other uses of the words tao and dao, see Dao (disambiguation). ... For the film of the same name, see Alexander the Great (1956 film). ...


Notes

  1. ^ Colin Ronan, "Astronomy in China, Korea and Japan," in Walker, ed., Astronomy Before the Telescope, pp. 264-5.
  2. ^ Thomas S. Kuhn, The Copernican Revolution, pp. 5-20
  3. ^ This argument is given in Book I, Chapter 5, of the Almagest (Crowe, 1990, pp.60–62).
  4. ^ Jon D. Miller. Retrieved on 2007-07-19.
  5. ^ Cornelia Dean. "Scientific Savvy? In U.S., Not Much", New York Times, 30 August 2005. Retrieved on 2007-07-19. 

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 200th day of the year (201st in leap years) in the Gregorian calendar. ... is the 242nd day of the year (243rd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 200th day of the year (201st in leap years) in the Gregorian calendar. ...

References

  • Crowe, Michael J. (1990). Theories of the World from Antiquity to the Copernican Revolution. Mineola, NY: Dover Publications, Inc. ISBN 0-486-26173-5. 
  • Dreyer, J. L. E.. A History of Astronomy from Thales to Kepler. 2nd edition. New York: Dover Publications, 1953.
  • Evans, James. The History and Practice of Ancient Astronomy. New York: Oxford University Press, 1998.
  • Heath, Thomas. Aristarchus of Samos. Oxford: Clarendon Press, 1913
  • Hoyle, Fred, Nicolaus Copernicus, 1973.
  • Koestler, Arthur The Sleepwalkers: A History of Man's Changing Vision of the Universe, 1959, Penguin Books, 1986 edition: ISBN 0-14-055212-X, 1990 reprint: ISBN 0-14-019246-8
  • Kuhn, Thomas S. The Copernican Revolution. Cambridge: Harvard Univ. Pr., 1957. ISBN 0-674-17103-9
  • Walker, Christopher, ed. Astronomy before the telescope. London: British Museum Press, 1996. ISBN 0-7141-1746-3

John Louis Emil Dreyer (February 13, 1852 – September 14, 1926) was a Danish-Irish astronomer. ... Thomas Little Heath (October 5, 1861 - March 16, 1940) was a mathematician, classical scholar, historian of ancient Greek mathematics, and translator. ... Sir Fred Hoyle (June 24, 1915 – August 20, 2001) was a British astronomer, notable for a number of his theories that run counter to current astronomical opinion, and a writer of science fiction, including a number of books co-authored by his son Geoffrey Hoyle. ... Arthur Koestler (September 5, 1905, Budapest – March 3, 1983, London) was a Hungarian polymath who became a naturalized British subject. ... 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. ...

See also

The celestial spheres relate to Johannes Keplers work Harmonia Mundi in which he drew together theories from the world of music, architecture, planetary motion and astronomy and linked them together to form an idea of a harmony and cohesion underlying all world phenomena and ruled by a divine force. ... Firmament is a name for the sky or the heavens, generally used in the context of Christianity, Judaism and Islam. ... 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. ...

External links

A recreation of the famous Library of Alexandria Greek astronomy is the astronomy of those who spoke Greek in classical antiquity. ... Acoreus was the name of a wise man consulted by Julius Caesar, according to the Roman writer Lucan, asking him many questions about ancient Egypt’s history and its calendar. ... Aglaonike (dates unknown), also known as Aganice of Thessaly is cited as the first female Astronomer in Ancient Greece. ... For other people named Agrippa, see Agrippa. ... This article is about the Pre-Socratic philosopher. ... Andronicus of Cyrrhus was a Greek astronomer who flourished about 100 BC. He built a horologium at Athens, the so-called Tower of the Winds, a considerable portion of which still exists. ... Apollonius of Perga [Pergaeus] (ca. ... Aratus (Greek Aratos) (ca. ... 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. ... For the crater, see Aristillus (crater). ... Autolycus of Pitane (c. ... Calippus of Syracuse Callippus (or Calippus) (ca. ... Cleomedes was a Greek astronomer who is known chiefly for his book On the Circular Motions of the Celestial Bodies. ... Cleostratus (ca. ... Conon of Samos (circa 280 BC - circa: 220 BC) was a Greek mathematician and astronomer. ... This article is about the Greek scholar of the third century BC. For the ancient Athenian statesman of the fifth century BC, see Eratosthenes (statesman). ... Euctemon (unknown-fl. ... Another article concerns Eudoxus of Cyzicus. ... Geminus of Rhodes was a Greek astronomer and mathematician. ... Heraclides Ponticus (387 - 312 BCE), also known as Heraklides, was a Greek philosopher who lived and died at Heraclea, now Eregli, Turkey. ... Hicetas (around 400 BC – around 335 BC) was a Greek philosopher of the Pythagorean School. ... For the Athenian tyrant, see Hipparchus (son of Pisistratus). ... Hippocrates of Chios was an ancient Greek mathematician (geometer) and astronomer, who lived c. ... Hypsicles (ca. ... Menelaus of Alexandria (c. ... Meton of Athens was a Greek mathematician, astronomer, geometer, and engineer who lived in Athens in the 5th century BCE. He is best known for the 19-year Metonic cycle which he introduced in 432 BCE into the lunisolar Attic calendar as a method of calculating dates. ... Oenopides of Chios was an ancient Greek mathematician (geometer) and astronomer, who lived around 450 BCE. He was born shortly after 500 BC on the island of Chios, but mostly worked in Athens. ... Philip of Opus was a philosopher and a member of the Academy during Platos lifetime. ... Philolaus (circa 480 BC – circa 405 BC) was a Greek mathematician and philosopher. ... The bust of Posidonius as an older man depicts his character as a Stoic philosopher. ... This article is about the geographer, mathematician and astronomer Ptolemy. ... Seleucus (or Seleukos) of Seleucia (born circa 190 BC - ?) was a Greek philosopher. ... Sosigenes of Alexandria was named by Pliny the Elder as the astronomer consulted by Julius Caesar for the design of the Julian calendar. ... Sporus of Nicaea was a Greek mathematician and astronomer, born: circa 240, probably Nicaea (Greek Nikaia), ancient district Bithynia, (modern-day Iznik) in province Bursa, in modern day Turkey, died: circa 300. ... For the Defense and Security Company, see Thales Group. ... Theodosius of Bithynia (ca. ... Theon (c. ... Theon of Smyrna (ca. ... Timocharis of Alexandria (ca. ... Almagest is the Latin form of the Arabic name (al-kitabu-l-mijisti, i. ... On Sizes and Distances [of the Sun and Moon] (Peri megethoon kai apostèmátoon) is a text by the ancient Greek astronomer Hipparchus. ... Aristarchuss 3rd century BC calculations on the relative sizes of the Earth, Sun and Moon, from a 10th century CE Greek copy On the Sizes and Distances [of the Sun and Moon] is the only extant work written by Aristarchus of Samos, an ancient Greek astronomer who lived circa... On the Heavens (or De Caelo) is Aristotles chief cosmological treatise: it contains his astronomical theory. ... The Antikythera mechanism (main fragment). ... Armillary sphere An armillary sphere (variations known as a spherical astrolabe, armilla, or armil) is a model of the celestial sphere, invented by the ancient Greek Eratosthenes in 255 BC. Its name comes from the Latin armilla (circle, bracelet), since it has a skeleton made of graduated metal circles linking... A 16th century astrolabe. ... A dioptra is a instrument dating back to ancient Greece, at least 300 B.C.E. It is said to have been long used by Greek astronomers, such as Hipparchus(sometimes credited with inventing it). ... Tycho Brahes mural quadrant A mural instrument is an angle measuring device mounted on or built into a wall. ... Drawing of a triquetrum by Wilhelm Schickard, Basel University Library A triquetrum, or three-staff, is an ancient astronomical instrument developed by Ptolemy in the 2nd century A.D. Comprised of two intersecting arms hinged to a vertical post, the triquetrum enabled calculation of the angular elevation of a heavenly... Eclipses may occur repeatedly, separated by some specific interval of time: this interval is called an eclipse cycle. ... The celestial spheres relate to Johannes Keplers work Harmonia Mundi in which he drew together theories from the world of music, architecture, planetary motion and astronomy and linked them together to form an idea of a harmony and cohesion underlying all world phenomena and ruled by a divine force. ... Counter-Earth is an Earth-like hypothetical planet, usually sharing an orbit with Earth but on the opposite side of the Sun. ... 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. ... Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ... 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. ... Eclipses may occur repeatedly, separated by some specific interval of time: this interval is called an eclipse cycle. ... The Metonic cycle or Enneadecaeteris in astronomy and calendar studies is a particular approximate common multiple of the year (specifically, the seasonal tropical year) and the synodic month. ... Medieval artistic representation of a spherical Earth - with compartments representing earth, air, and water (c. ... The Sublunary Sphere is a concept derived from Greek astronomy. ...


 
 

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