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Encyclopedia > Celestial orb
Concentric celestial spheres; Peter Apian's Cosmographia (Antwerp, 1539)
Concentric celestial spheres; Peter Apian's Cosmographia (Antwerp, 1539)

The Celestial spheres, or Celestial orbs, are the fundamental element of Earth-centered (geocentric) astronomies and cosmologies developed by Plato, Aristotle, Ptolemy, and others. In these geocentric models the stars and planets were carried around the Earth on spheres or circles. Note that the spheres carry the planets and thus are not to be confused with the modern concept of the spherical planets themselves. Image File history File links Ptolemaicsystem-small. ... Image File history File links Ptolemaicsystem-small. ... The celestial sphere is divided by the celestial equator. ... The geocentric model (in Greek: geo = earth and centron = centre) of the universe is a paradigm which places the Earth at its center. ... Greek astronomy is the astronomy of those who spoke Greek in classical antiquity. ... This artistic representation of the geocentric model shows signs of the zodiac and the solar system with world at centre. ... This article is about the astronomical object. ... For the astrological concept, see Planets in astrology. ... Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ...


The spheres were most commonly arranged outwards from the center in the order: the sphere of the Moon, the sphere of Mercury, the sphere of Venus, the sphere of the Sun, the sphere of Mars, the sphere of Jupiter, the sphere of Saturn, the starry firmament, and sometimes one or two additional spheres. The order of the lower planets was not universally agreed. Plato and his followers ordered them beginning with the sphere of the Moon, of the Sun, of Mercury, of Venus and then followed the standard model for the upper spheres; there were further disagreements on the relative place of the spheres of Mercury and Venus.

Contents

History

Antiquity

One of the earliest intimations of celestial spheres appears in Plato's "Myth of Er," a section of the Republic, which describes the cosmos as the Spindle of Necessity, attended by the Sirens and turned by the three Fates. For other uses, see Plato (disambiguation). ... 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). ...


In his Metaphysics, Aristotle developed a philosophical cosmology of spheres, based on the mathematical astronomy of Eudoxus and Callippus. In the fully developed Aristotelian system, the spherical Earth is at the center of the universe. The planets are attached to anywhere from 47 to 55 concentric spheres that rotate around the Earth. Aristotle considers that these spheres are made of an unchanging fifth element, the Aether, and each of these concentric spheres is moved by a god -- an unchanging divine mover. Aristotle says that to determine the exact number of spheres, and the number of divine movers, one should consult the astronomers.[1][2] Plato and Aristotle (right), by Raphael (Stanza della Segnatura, Rome). ... Aristotle (Greek: Aristotélēs) (384 BC – March 7, 322 BC) was a Greek philosopher, a student of Plato and teacher of Alexander the Great. ... Eudoxus was the name of two ancient Greeks: Eudoxus of Cnidus (c. ... Callippus (or Calippus) (circa 370 B.C.–circa 300 B.C.) was a Greek astronomer. ... Chinese Wood (木) | Fire (火) | Earth (土) | Metal (金) | Water (水) Hinduism and Buddhism The Pancha Mahabhuta (The Five Great Elements) Vayu/Pavan (Air/Wind) Agni/Tejas (Fire) Akasha (Aether) Prithvi/Bhumi (Earth) Ap/Jala (Water) Aether (also spelled ether) is a concept used in ancient and medieval science as a substance. ...

Ptolemaic model of the spheres for Venus, Mars, Jupiter, and Saturn with epicycle, eccentric deferent and equant point. Georg von Peuerbach, Theoricae novae planetarum, 1474.

The astronomer Ptolemy (fl. ca. 150 AD) defined a geometrical model of the universe in his Almagest and extended it to a physical model of the Cosmos in his Planetary hypotheses. In doing so, he added mathematical detail and predictive accuracy that had been lacking in ealier spherical models of the cosmos. In Ptolemy's model, each planet is moved by two or more spheres (or strictly speaking, by thick equatorial slices of spheres): one sphere is the deferent with a center offset somewhat from the Earth, the other sphere is an epicycle which is embedded in the deferent, and the planet is embedded in the spherical epicycle. Through the use of the epicycle, eccentric, and equant, this model of compound circular motions could account for all the irregularities of a planet's appearances.[3] Image File history File links Download high-resolution version (1141x1529, 693 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Scientific revolution ... Image File history File links Download high-resolution version (1141x1529, 693 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Scientific revolution ... 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. ... 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. ... Georg Purbach (also Georg von Peuerbach, Peurbach, Purbach, Purbachius, his real surname is unknown) (born May 30, 1423 in Purbach near Linz– April 8, 1461 in Vienna) was an Austrian astronomer and mathematician. ... A medieval artists rendition of Claudius Ptolemaeus Claudius Ptolemaeus (Greek: ; c. ... Almagest is the Latin form of the Arabic name (al-kitabu-l-mijisti, i. ... The Ancient and Medieval cosmos as depicted in Peter Apians Cosmographia (Antwerp, 1539). ... 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. ...


Middle Ages

Christian and Muslim philosophers modified Ptolemy's system to include an unmoved outermost sphere, which was the dwelling place of God and all the elect. Each of the lower spheres was moved by a subordinate spiritual mover, a replacement for Aristotle's multiple divine movers, called an intelligence. The outermost mover, whose movement affected all others, was referred to as the Prime Mover and identified with God. This article discusses the term God in the context of monotheism and henotheism. ... This article or section does not cite its references or sources. ...


Near the end of the Twelfth Century, the Spanish Muslim, al-Bitrūjī, sought to explain the complex motions of the planets using purely concentric spheres, which moved with differing speeds from East to West. This model was an attempt to restore the concentric spheres of Aristotle, without Ptolemy's epicycles and eccentrics, but it was much less accurate as a predictive astronomical model.[4][5] Nur Ed-Din Al Betrugi (also spelled Nur al-Din Ibn Ishaq Al-Bitruji and Abu Ishâk ibn al-Bitrogi; another spelling is al Bidrudschi) (known in the West by the Latinized name of Alpetragius) (died ca. ...


In the Thirteenth Century, scholars in the Medieval Universities dealt with the implications of the rediscovered philosophy of Aristotle and astronomy of Ptolemy. One issue that arose concerned the nature of the celestial spheres. Through an extensive examination of a wide range of scholastic texts, Edward Grant has demonstrated that scholastic philosophers generally considered the celestial spheres to be solid in the sense of three dimensional or continuous, but most did not consider them solid in the sense of hard. The consensus was that the celestial spheres were made of some kind of continuous fluid. [6]


Renaissance

Early in the Sixteenth Century Nicolaus Copernicus drastically reformed the model of astronomy by displacing the Earth from its central place, yet he called his great work De revolutionibus orbium coelestium, On the Revolutions of the Celestial Spheres. Although Copernicus does not treat the physical nature of the spheres in detail, his few allusions make it clear that, like many of his predecessors, he accepted non-solid celestial spheres.[7] Nicolaus Copernicus (February 19, 1473 – May 24, 1543) was the astronomer who formulated the first modern heliocentric theory of the solar system. ... Title page of De revolutionibus De revolutionibus orbium coelestium (English: On the Revolutions of the Heavenly Spheres, Polish: O obrotach sfer niebieskich) is the seminal work on heliocentric theory and the masterpiece of the great Polish astronomer Nicolaus Copernicus. ...


Tycho Brahe's observation of the comet of 1577, which passed through the planetary orbs, led him to conclude that "the structure of the heavens was very fluid and simple." Tycho opposed his view to that of "very many modern philosophers" who divided the heavens into "various orbs made of hard and impervious matter." Since Grant has been unable to identify such a large number of believers in hard celestial spheres before Copernicus, he concludes that the idea first became dominant sometime after the publication of Copernicus's De revolutionibus in 1542 and either before, or possibly somewhat after, Tycho Brahe's publication of his cometary observations in 1588.[8][9] Tycho Brahe Monument of Tycho Brahe and Johannes Kepler in Prague   , born Tyge Ottesen Brahe (December 14, 1546 – October 24, 1601), was a Danish (Scanian) nobleman best known today as an early astronomer, though in his lifetime he was also well known as an astrologer and alchemist. ...


Although in his early works Johannes Kepler drew upon the notion of celestial spheres, by the Epitome of Copernican Astronomy (1621) Kepler questioned the existence of solid spheres and consequently the need for intelligences to guide the motions of the heavens. The immobile sphere of the fixed stars, however, was the lasting remnant of the celestial spheres in Kepler's thought.[10] Johannes Kepler (December 27, 1571 – November 15, 1630) was a German Lutheran mathematician, astronomer and astrologer, and a key figure in the 17th century astronomical revolution. ...


Literary and symbolic expressions

Dante and Beatrice gaze upon the highest Heaven; from Gustave Doré's illustrations to the Divine Comedy Paradiso Canto 31
Dante and Beatrice gaze upon the highest Heaven; from Gustave Doré's illustrations to the Divine Comedy Paradiso Canto 31

In Cicero's Dream of Scipio, the elder Scipio Africanus describes an ascent through the celestial spheres, compared to which the Earth and the Roman Empire dwindle into insignificance. A commentary on the Dream of Scipio by the late Roman writer, Macrobius did much to spread the idea of the celestial spheres through the Early Middle Ages, including a discussion of the various schools of thought on the order of the spheres.[11] Image File history File links Download high resolution version (858x952, 205 KB) Dante and Beatrice gaze upon the highest Heaven (The Empyrean); from Gustave Dorés illustrations to the Divine Comedy, Paradiso Canto 31. ... Image File history File links Download high resolution version (858x952, 205 KB) Dante and Beatrice gaze upon the highest Heaven (The Empyrean); from Gustave Dorés illustrations to the Divine Comedy, Paradiso Canto 31. ... Dante in a fresco series of famous men by Andrea del Castagno, ca. ... Although the details surrounding the life of Beatrice Portinari, pronounced bay-a-treech-eh, (1266-1290) are subject to much dispute, there is little doubt she was a major influence in Dante Alighieris life, influencing particularly his works of La Vita Nuova and La Divina Commedia. ... Doré photographed by Felix Nadar. ... Dante shown holding a copy of The Divine Comedy, next to the entrance to Hell, the seven terraces of Mount Purgatory and the city of Florence, in Michelinos fresco. ... Cicero at about age 60, from an ancient marble bust Marcus Tullius Cicero (IPA: ; Classical pronunciation:  ; January 3, 106 BC – December 7, 43 BC) was an orator, statesman, political theorist, lawyer and philosopher of Ancient Rome. ... The Dream of Scipio (Latin, Somnium Scipionis) is a dream-vision by the Roman philosopher Cicero in which Scipio Aemilianus Africanus meets his grandfather by adoption, Scipio Africanus Major (236 BC - 184 BC), hero of the Second Punic War against Hannibals Carthage. ... Publius Cornelius Scipio Africanus Major (Latin: P·CORNELIVS·P·F·L·N·SCIPIO·AFRICANVS¹) (235–183 BC) was a general in the Second Punic War and statesman of the Roman Republic. ... Ambrosius Theodosius Macrobius, Roman grammarian and philosopher, flourished during the reigns of Honorius and Arcadius (395-423). ... Justinians wife Theodora and her retinue, in a 6th century mosaic from the Basilica of San Vitale in Ravenna. ...

Nicole Oresme, Le livre du Ciel et du Monde, Paris, BnF, Manuscrits, Fr. 565, fo 69, 1377
Nicole Oresme, Le livre du Ciel et du Monde, Paris, BnF, Manuscrits, Fr. 565, fo 69, 1377

Some late medieval figures inverted the model of the celestial spheres to place God at the center and the Earth at the periphery. Near the beginning of the Fourteenth Century Dante, in the Paradiso of his Divine Comedy, describes God as a light at the center of the Cosmos.[12]. Here the poet ascends beyond physical existence to the Empyrean Heaven, where he comes face-to-face with God Himself, and is granted understanding of the Divine and of human nature. Dante redirects here. ... Dante shown holding a copy of The Divine Comedy, next to the entrance to Hell, the seven terraces of Mount Purgatory and the city of Florence, in Michelinos fresco. ... The Divine Comedys Empyrean, illustrated by Gustave Doré Empyrean, from the Medieval Latin empyreus, an adaptation of the Ancient Greek, in or on the fire (pyr), properly Empyrean Heaven, is the place in the highest heaven, which in ancient cosmologies was supposed to be occupied by the element of...


Later in the century, the illuminator of Nicole Oresme's Le livre du Ciel et du Monde, a translation of and commentary on Aristotle's De caelo produced for Oresme's patron, King Charles V, employed the same motif. He drew the spheres in the conventional order with the Moon closest to the Earth and the stars hightest, but the spheres were concave upwards, centered on God, rather than concave downwards, centered on the Earth.[13] Below this figure Oresme quotes the Psalms that "The heavens declare the Glory of God and the firmament showeth his handiwork."[14] Portrait of Nicole Oresme: Miniature of Nicole Oresmes Traité de l’espere, Bibliothèque Nationale, Paris, France, fonds français 565, fol. ... Charles V the Wise (French: Charles V le Sage) (January 31, 1338 – September 16, 1380) was king of France from 1364 to 1380 and a member of the Valois Dynasty. ... Psalms (Hebrew: Tehilim, תהילים) is a book of the Hebrew Bible or Tanakh. ...


Notes

  1. ^ G. E. R. Lloyd, Aristotle: The Growth and Structure of his Thought, pp. 133-153, Cambridge: Cambridge Univ. Pr., 1968. ISBN 0-521-09456-9.
  2. ^ G. E. R. Lloyd, "Heavenly aberrations: Aristotle the amateur astronomer," pp.160-183 in his Aristotelian Explorations, Cambridge: Cambridge Univ. Pr., 1996. ISBN 0-521-55619-8.
  3. ^ Andrea Murschel, "The Structure and Function of Ptolemy's Physical Hypotheses of Planetary Motion," Journal for the History of Astronomy, 26(1995): 33-61.
  4. ^ Bernard R. Goldstein, Al-Bitrūjī: On the Principles of Astronomy, New Haven: Yale Univ. Pr., 1971, vol. 1, pp. 6, 44-5
  5. ^ Grant, Planets, Stars, and Orbs, pp. 563-4
  6. ^ Grant, Planets, Stars, and Orbs, pp. 328-30.
  7. ^ Nicholas Jardine, "The Significance of the Copernican Orbs," Journal for the History of Astronomy, 13(1982): 168-194, esp. pp. 177-8.
  8. ^ Grant, "Celestial Orbs," 2000, pp. 185-6.
  9. ^ Grant, Planets, Stars, and Orbs, pp. 345-8.
  10. ^ Grant, Planets, Stars, and Orbs, pp. 121, 544-5.
  11. ^ Macrobius, Commentary on the Dream of Scipio, transl. by William Harris Stahl, New York: Columbia Univ. Pr., 1952; on the order of the spheres see pp. 162-5.
  12. ^ C. S. Lewis, The Discarded Image: An Introduction to Medieval and Renaissance Literature, Cambridge: Cambridge Univ. Pr., 1964, p. 116. ISBN 0-521-09450-X
  13. ^ http://expositions.bnf.fr/ciel/grand/1-025.htm
  14. ^ Ps. 18: 2; quoted in Nicole Oresme, Le livre du ciel et du monde, edited and translated by A, D. Menut and A. J. Denomy, Madison: Univ. of Wisconsin Pr., 1968, pp. 282-3.

Bibliography

  • Duhem, Pierre, Le Système du Monde: Histoire des doctrines cosmologiques de Platon à Copernic, 10 vols., Paris: Hermann, 1959.
  • Eastwood, Bruce, "Astronomy in Christian Latin Europe c. 500 – c. 1150," Journal for the History of Astronomy, 28(1997): 235–258.
  • Eastwood, Bruce and Gerd Graßhoff, Planetary Diagrams for Roman Astronomy in Medieval Eyrope, ca. 800-1500, Transactions of the American Philosophical Society, vol. 94, pt. 3, Philadelphia, 2004. ISBN 0-87169-943-5
  • Grant, Edward, "Celestial Orbs in the Latin Middle Ages," Isis, 78(1987): 153-73; reprinted in Michael H. Shank, ed., The Scientific Enterprise in Antiquity and the Middle Ages, Chicago: Univ. of Chicago Pr., 2000. ISBN 0-226-74951-7
  • Grant, Edward, Planets, Stars, and Orbs: The Medieval Cosmos, 1200-1687, Cambridge: Cambridge Univ. Pr., 1996. ISBN 0-521-56509-X
  • McCluskey, Stephen C., Astronomies and Cultures in Early Medieval Europe, Cambridge: Cambridge Univ. Pr., 1998. ISBN 0-521-77852-2
  • Thoren, Victor E., "The Comet of 1577 and Tycho Brahe's System of the World," Archives Internationales d'Histoire des Sciences, 29(1979): 53-67.

See also

Firmament refers to the sky or the heavens. ...

External Links

Dennis Duke, Animated Ptolemaic model of the nested spheres


 
 

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