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Encyclopedia > Armillary sphere
Armillary sphere
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 the poles and representing the equator, the ecliptic, meridians and parallels. Usually a ball representing the Earth or, later, the Sun is placed in its center. It is used to demonstrate the motion of the stars around the Earth. The Chinese during the 1st century BC (Western Han Dynasty) also invented the armillary sphere, while the 2nd century Chinese astronomer Zhang Heng is credited as the world's first to apply motive power (using hydraulics) in rotating his armillary sphere. Download high resolution version (900x1200, 65 KB)Description: Illustration for Armillary sphere Source: Scanned by me (looxix) from the Encyclopédie. ... Download high resolution version (900x1200, 65 KB)Description: Illustration for Armillary sphere Source: Scanned by me (looxix) from the Encyclopédie. ... A 16th century astrolabe. ... The celestial sphere is divided by the celestial equator. ... Eratosthenes (Greek ; 276 BC - 194 BC) was a Greek mathematician, geographer and astronomer. ... Centuries: 4th century BC - 3rd century BC - 2nd century BC Decades: 300s BC 290s BC 280s BC 270s BC 260s BC - 250s BC - 240s BC 230s BC 220s BC 210s BC 200s BC Years: 260 BC 259 BC 258 BC 257 BC 256 BC - 255 BC - 254 BC 253 BC... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... World map showing the equator in red For other uses, see Equator (disambiguation). ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... This article is about the astronomical concept. ... On the Earth, a circle of latitude or parallel is an imaginary east-west circle that connects all locations with a given latitude. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... The Sun is the star at the center of the Solar System. ... Celestial mechanics is a division of astronomy dealing with the motions and gravitational effects of celestial objects. ... This article is about the astronomical object. ... (2nd millennium BC - 1st millennium BC - 1st millennium) The 1st century BC started on January 1, 100 BC and ended on December 31, 1 BC. An alternative name for this century is the last century BC. The AD/BC notation does not use a year zero. ... The Han Dynasty (Traditional Chinese characters: 漢朝, Simplified Chinese characters: 汉朝, pinyin Hàncháo 202 BC - AD 220) followed the Qin Dynasty and preceded the Three Kingdoms in China. ... The 2nd century is the period from 101 - 200 in accordance with the Julian calendar in the Christian Era. ... Zhāng Héng Replica of Zhang Hengs seismometer Houfeng Didong Yi For other uses, see Zhang Heng (disambiguation). ... Table of Hydraulics and Hydrostatics, from the 1728 Cyclopaedia. ...


In its simplest form, consisting of a ring fixed in the plane of the equator, the armilla is one of the most ancient of astronomical instruments. Slightly developed, it was crossed by another ring fixed in the plane of the meridian. The first was an equinoctial, the second a solstitial armilla. Shadows were used as indices of the sun's positions, in combinations with angular divisions. When several rings or circles were combined representing the great circles of the heavens, the instrument became an armillary sphere.


Eratosthenes used most probably a solstitial armilla for measuring the obliquity of the ecliptic. Hipparchus probably used an armillary sphere of four rings. Ptolemy describes his instrument in the Syntaxis (book v. chap. i.), and it is of great interest as an example of the armillary sphere passing into the spherical astrolabe. It consisted of a graduated circle inside which another could slide, carrying to small tubes diametrically opposite, the instrument being kept vertical by a plumb-line. For the Athenian tyrant, see Hipparchus (son of Pisistratus). ... A medieval artists rendition of Claudius Ptolemaeus Claudius Ptolemaeus (Greek: ; c. ...


Armillary spheres were developed by the Greeks and were used as teaching tools already in the 3rd century B.C.. In larger and more precise forms they were also used as observational instruments. No material advance was made on Ptolemy's instrument until Tycho Brahe, whose elaborate armillary spheres passing into astrolabes are figured in his Astronomiae Instauratae Mechanica. Armillary spheres became popular again in the Late Middle Ages; the Danish astronomer Tycho Brahe (1546-1601) constructed several of such instruments. (2nd millennium BC - 1st millennium BC - 1st millennium) The 3rd century BC started on January 1, 300 BC and ended on December 31, 201 BC. // Events The Pyramid of the Moon, one of several monuments built in Teotihuacán Teotihuacán, Mexico begun The first two Punic Wars between Carthage... Tycho Brahe Monument of Tycho Brahe and Johannes Kepler in Prague Tycho Brahe, born Tyge Ottesen Brahe (December 14, 1546 – October 24, 1601), was a Danish nobleman from the region of Scania (in modern-day Sweden), best known today as an early astronomer, though in his lifetime he was also... Dante by Michelino The Late Middle Ages is a term used by historians to describe European history in the period of the 14th and 15th centuries (1300–1500 A.D.). The Late Middle Ages were preceded by the High Middle Ages, and followed by the Early Modern era (Renaissance). ... Tycho Brahe Monument of Tycho Brahe and Johannes Kepler in Prague Tycho Brahe, born Tyge Ottesen Brahe (December 14, 1546 – October 24, 1601), was a Danish nobleman from the region of Scania (in modern-day Sweden), best known today as an early astronomer, though in his lifetime he was also... // Events Spanish conquest of Yucatan Peace between England and France Foundation of Trinity College, Cambridge by Henry VIII of England Katharina von Bora flees to Magdeburg Science Architecture Michelangelo Buonarroti is made chief architect of St. ... Events February 8 - Robert Devereux, 2nd Earl of Essex, rebels against Elizabeth I of England - revolt is quickly crushed February 25 - Robert Devereux beheaded Jesuit Matteo Ricci arrives in China Bad harvest in Russia due to rainy summer Dutch troops drive Portuguese from Málaga Battle of Kinsale, Ireland Births...


Renaissance scientists and public figures often had their portraits painted showing them with one hand on an armillary sphere, which represented the height of wisdom and knowledge. Raphael was famous for depicting illustrious figures of the Classical past with the features of his Renaissance contemporaries. ... This article or section does not adequately cite its references or sources. ... Personification of knowledge (Greek Επιστημη, Episteme) in Celsus Library in Ephesos, Turkey. ...


Armillary spheres were among the first complex mechanical devices. Their development led to many improvements in techniques and design of all mechanical devices.


The armillary sphere survives as useful for teaching, and may be described as a skeleton celestial globe, the series of rings representing the great circles of the heavens, and revolving on an axis within a horizon. With the earth as center such a sphere is known as Ptolemaic; with the sun as center, as Copernican.


A representation of an armillary sphere is present in the modern flag of Portugal and has been a national symbol since the reign of Manuel I. Flag Ratio: 2:3 The flag of the Portuguese Republic is a 2:3 green and red rectangle divided vertically into green at the hoist (2/5 of the flag’s length) and red at the fly (3/5). ... Manuel I of Portugal (pron. ...

Contents

The description and use of the armillary sphere

Armillary sphere diagram

The exterior parts of this machine are a compages of brass rings, which represent the principal circles of the heaven. Image File history File links Size of this preview: 406 × 599 pixel Image in higher resolution (2096 × 3092 pixel, file size: 3. ... Image File history File links Size of this preview: 406 × 599 pixel Image in higher resolution (2096 × 3092 pixel, file size: 3. ...

  1. The equinoctial A, which is divided into 360 degrees (beginning at its intersection with the ecliptic in Aries) for showing the sun's right ascension in degrees; and also into 24 hours, for showing his right ascension in time.
  2. The ecliptic B, which is divided into 12 signs, and each sign into 30 degrees, and also into the months and days of the year; in such a manner, that the degree or point of the ecliptic in which the sun is, on any given day, stands over that day in the circle of months.
  3. The tropic of Cancer C, touching the ecliptic at the beginning of Cancer in e, and the tropic of Capricorn D, touching the ecliptic at the beginning of Capricorn in f; each 23½ degrees from the equinoctial circle.
  4. The Arctic Circle E, and the Antarctic Circle F, each 23½ from its respective pole at N and S.
  5. The equinoctial colure G, passing through the north and south poles of the heaven at N and S, and through the equinoctial points Aries and Libra, in the ecliptic.
  6. The solstitial colure H, passing through the poles of the heaven, and through the solstitial points Cancer and Capricorn, in the ecliptic. Each quarter of the former of these colures is divided into 90 degrees, from the equinoctial to the poles of the world, for showing the declination of the sun, moon, and stars; and each quarter of the latter, from the ecliptic as e and f, to its poles b and d, f or showing the latitude of the stars.

In the north pole of the ecliptic is a nut b, to which is fixed one end of the quadrantal wire, and to the other end a small sun Ψ, which is carried round the ecliptic BB, by turning the nut : and in the south pole of the ecliptic is a pin d, on which is another quadrantal wire, with a small moon Ζ upon it, which may be moved round by hand : but there is a particular contrivance for causing the moon to move in an orbit which crosses the ecliptic at an angle of 5⅓ degrees, in to opposite points called the moon's nodes; and also for shifting these points backward in the ecliptic, as the moon's nodes shift in the heaven.


Within these circular rings is a small terrestrial globe J, fixed on an axis K, which extends from the north and south poles of the globe at n and s, to those of the celestial sphere at N and S. On this axis is fixed the flat celestial meridian L L, which may be set directly over the meridian of any place on the globe, so as to keep over the same meridian upon it. This flat meridian is graduated the same way as the brass meridian of the common globe, and its use is much the same. To this globe is fitted the movable horizon M, so as to turn upon the two strong wires proceeding from its east and west points to the globe, and entering the globe at the opposite points off its equator, which is a movable brass ring set into the globe in a groove all around its equator. The globe may be turned by hand within this ring, so as to place any given meridian upon it, directly under the celestial meridian L. The horizon is divided into 360 degrees all around its outermost edge, within which are the points of the compass, for showing the amplitude of the sun and the moon, both in degrees and points. The celestial meridian L passes through two notches in the north and south points of the horizon, as in a common globe: both here, if the globe be turned round, the horizon and meridian turn with it. At the south pole of the sphere is a circle of 25 hours, fixed to the rings, and on the axis is an index which goes round that circle, if the globe be turned round its axis.


The whole fabric is supported on a pedestal N, and may be elevated or depressed upon the joint O, to any number of degrees from 0 to 90, by means of the arc P, which is fixed in the strong brass arm Q, and slides in the upright piece R, in which is a screw at r, to fix it at any proper elevation.


In the box T are two wheels (as in Dr Long's sphere) and two pinions, whose axes come out at V and U; either of which may be turned by the small winch W. When the winch is put upon the axis V, and turn backward, the terrestrial globe, with its horizon and celestial meridian, keep at rest; and the whole sphere of circles turns round from east, by south, to west, carrying the sun Y, and moon Z, round the same way, and causing them to rise above and set below the horizon. But when the winch is put upon the axis U, and turned forward, the sphere with the sun and moon keep at rest; and the earth, with its horizon and meridian, turn round from horizon to the sun and moon, to which these bodies came when the earth kept at rest, and they were carried round it; showing that they rise and set in the same points of the horizon, and at the same times in the hour circle, whether the motion be in the earth or in the heaven. If the earthly globe be turned, the hour-index goes round its hour-circle; but if the sphere be turned, the hour-circle goes round below the index.


And so, by this construction, the machine is equally fitted to show either the real motion of the earth, or the apparent motion of the heaven.


To rectify the sphere for use, first slacken the screw rin the upright stem R, and taking hold of the arm Q, move it up or down until the given degree of latitude for any place be at the side of the stem R; and then the axis of the sphere will be properly elevated, so as to stand parallel to the axis of the world, if the machine be set north and south by a small compass: this done, count the latitude from the north pole, upon the celestial meridian L, down towards the north notch of the horizon, and set the horizon to that latitude; then, turn the nut b until the sun Y comes to the given day of the year in the ecliptic, and the sun will be at its proper place for that day: find the place of the moon's ascending node, and also the place of the moon, by an Ephemeris, and set them right accordingly: lastly, turn the winch W, until either the sun comes to the meridian L, or until the meridian comes to the sun (according as you want the sphere or earth to move) and set the hour-index to the XXI, marked noon, and the whole machine will be rectified. — Then turn the winch, and observe when the sun or moon rise and set in the horizon, and the hour-index will show the times thereof for the given day.


Development in East Asia

Celestial globe from Qing Dynasty
Celestial globe from Qing Dynasty

Throughout Chinese history, astronomers have created celestial globes to assist the observation of the stars. Download high resolution version (480x609, 149 KB)Replica of a Celestial Globe from Qing Dynasty of China. ... Download high resolution version (480x609, 149 KB)Replica of a Celestial Globe from Qing Dynasty of China. ... An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ...


The earliest celestial globe was dated back to 52 BC in the West Han dynasty by the astronomers Geng Shou-chang (耿壽昌) and Luo-xia Hong (落下閎). The first water powered celestial globe was created by Zhang Heng(张衡) in the East Han dynasty. A Roman law prohibits the execution of old and crippled slaves. ... Later Han redirects here. ... Zhāng Héng Replica of Zhang Hengs seismometer Houfeng Didong Yi For other uses, see Zhang Heng (disambiguation). ... The Han Dynasty (Traditional Chinese characters: 漢朝, Simplified Chinese characters: 汉朝, pinyin Hàncháo 202 BC - AD 220) followed the Qin Dynasty and preceded the Three Kingdoms in China. ...


Then Li Chun-feng (李淳風) of the Tang dynasty created one in 633 AD with three spherical layers to calibrate multiple aspects of astronomical observations. The Tang Dynasty (Chinese: ; pinyin: ) (18 June 618 – 4 June 907), lasting about three centuries, preceded by the Sui Dynasty and followed by the Song Dynasty and the Five Dynasties and Ten Kingdoms Period in China. ... Events Oswald of Bernicia becomes Bretwalda. ...


In 723 AD, Tang dynasty Buddhist monk Yi-xing (一行) and government official Liang Ling-zan (梁令瓚) combined Zhang Heng's water powered celestial globe with an escapement device. The result was allegedly the world's first water powered mechanical clock. Events Saint Boniface fells Thors Oak near Fritzlar, marking the decisive event in the Christianization of the northern Germanic tribes The worlds first mechanical clock is allegedly built in China. ... The Tang Dynasty (Chinese: ; pinyin: ) (18 June 618 – 4 June 907), lasting about three centuries, preceded by the Sui Dynasty and followed by the Song Dynasty and the Five Dynasties and Ten Kingdoms Period in China. ... Yi Xing (Yi-xing) (一行) (683 – 727) was a Chinese astronomer and buddhist monk of the Tang Dynasty. ...


Jang Yeong-sil, a Korean inventor, was ordered by King Sejong the Great of Joseon to build an armillary sphere. The sphere, built in 1433 was named Honcheonui (혼천의). Jang Yeong-sil was a Korean scientist and astronomer during the Joseon Dynasty under King Sejong. ... King Sejong the Great (May 6, 1397 - May 18, 1450), born I Do, was the fourth ruler of the Joseon Dynasty of Korea from 1418 to 1450. ... Events Births June 23 - Francis II, Duke of Brittany Kettil Karlsson Vasa, later Regent of Sweden. ...


The Honcheonsigye, an armillary sphere activated by a working clock mechanism was built by the Korean astronomer Song Iyeong in 1669. It is highly valued in term of clock-making technology and is the only remaining astronomical clock from the Joseon Dynasty. The Honcheonsigye is an astronomical clock created by Song I-yeong in 1669. ... // Events Samuel Pepys stopped writing his diary. ... Territory of Joseon after Jurchen conquest of King Sejong Capital Hanseong Language(s) Korean Religion Confucianism Government Monarchy Wang  - 1392 - 1398 Taejo  - 1418 - 1450 Sejong  - 1776 - 1800 Jeongjo  - 1863 - 1897 Proclaimed Emperor Gojong Yeong-uijeong  - 1431 - 1449 Hwang Hui  - 1466 - 1472 Han Myeonghoe  - 1592 - 1598 Ryu Seongryong  - 1894 Kim Hongjip...


See also

The Antikythera mechanism (main fragment) The Antikythera mechanism (Greek: O μηχανισμός των Αντικυθήρων transliterated as O mÄ“chanismós tōn AntikythÄ“rōn) is an ancient mechanical analog computer (as opposed to most computers today which are digital computers) designed to calculate astronomical positions. ... A 16th century astrolabe. ... Prague astronomical clock Astronomical clock in Lund Cathedral An astronomical clock is a clock with special mechanisms and dials to display the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets. ... A small orrery showing earth and the inner planets An orrery is a mechanical device that illustrates the relative positions and motions of the planets and moons in the solar system in heliocentric model. ... Jupiter at South Station, part of Museum of Science, Boston scale model This was also used in FETCH! with Ruff Ruffman Solar system models, especially mechanical models, called orreries, that illustrate the relative positions and motions of the planets and moons in the solar system have been built for centuries. ... // 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 astronomical clock in the Old-Town Square of Prague The Prague Astronomical Clock or Prague Orloj (Czech: Pražský orloj, pron. ... The Torquetum or Turquet is a medieval astronomical instrument designed to take and convert measurements made in three sets of coordinates: Horizon, equatorial, and ecliptic. ... The celestial sphere is divided by the celestial equator. ... Chinese constellations are different from the western constellations, due to the independent development of ancient Chinese astronomy. ... Chinese astrology (占星術 pinyin: zhan4 xing1 shu4; 星學 pinyin: xing1 xue2; 七政四餘 pinyin: qi1 zheng4 si4 yu2; and 果老星宗 pinyin: guo3 lao3 xing1 zong1) is related to the Chinese calendar, particularly its 12-year cycle of animals (aka Chinese Zodiac), and... Jang Yeong-sil was a Korean scientist and inventor during the Joseon Dynasty under King Sejong. ... De sphaera mundi (Latin meaning Of the Spheres of Worlds, sometimes rendered The Sphere of the Cosmos; the Latin title is also given as Tractatus de sphaera, or simply De sphaera) is a medieval astronomy textbook written by Johannes de Sacrobosco c. ...

References

  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition article "Armilla" by Margaret Lindsay Huggins, a publication now in the public domain.
  • Encyclopaedia Britannica (1771), "Geography".

Encyclopædia Britannica, the 11th edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... Margaret Lindsay Huggins (born in 1848 in Dublin; died in 1915) was a British astronomer. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...

External links

Wikimedia Commons has media related to:
Armillary sphere

  Results from FactBites:
 
The Armillary Sphere (375 words)
Armillary spheres can be divided into two main categories: the observational armillary, as used by Ptolemy and Tycho Brahe; and the demonstrational instrument.
The armillary sphere described by Ptolemy was a zodiacal instrument of six rings, designed to determine the locations of celestial objects according to the ecliptic co-ordinate system.
The orientation of the instrument was establishing by sighting on a celestial object (the sun or a star) whose position in the ecliptic - that is, its celestial longitude - was known.
Armillary sphere (181 words)
An armillary sphere (also known as spherical astrolabe) is a model of the celestial sphere.
Armillary spheres were developed by the Greeks and were used as teaching tools already in the III century B.C. In larger and more precise forms they were also used as observational instruments, being preferred by Ptolemy.
Armillary spheres became popular again in the late middle ages; the Danish astronomer Tycho Brahe (1546-1601) constructed several of such instruments.
  More results at FactBites »

 
 

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