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Encyclopedia > Orrery
A small orrery showing earth and the inner 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. They are typically driven by a large clockwork mechanism with a globe representing the Sun at the centre, and with a planet at the end of each of the arms. Image File history File links Orrery_small. ... Image File history File links Orrery_small. ... The eight planets and three dwarf planets of the Solar System. ... Moons of the Solar System scaled to Earths Moon A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt containing the dwarf planet Ceres, outermost there is the dwarf planet Pluto (the dwarf planet Eris not shown), and a comet. ... In astronomy, heliocentrism is the theory that the Sun is at the center of the Universe and/or the Solar System. ... Gear with escapment mechanism In mechanical engineering, a clockwork is either a lightweight mechanical linkage, especially one involving multiple axles, or a complete mechanical device whose functioning relies on internal clockwork (in the preceding sense), especially where muscular effort is the sole source of operating power. ... The Sun is the star of our solar system. ...

Contents

History

According to Cicero, the Greek Stoic Philosopher Posidonius constructed an orrery, possibly similar or identical to the Antikythera mechanism, which exhibited the diurnal motions} of the sun, moon, and the five known planets. Cicero's account was written in the first century BC. 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. ... Stoicism is a school of philosophy commonly associated with such Greek philosophers as Zeno of Citium, Cleanthes, or Chrysippus and with such later Romans as Cicero, Seneca, Marcus Aurelius, and Epictetus. ... A philosopher is a person who thinks deeply regarding people, society, the world, and/or the universe. ... The bust of Posidonius as an older man depects his character as a Stoic philosopher. ... 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 digital computer) designed to calculate astronomical positions. ... Diurnal motion is an astronomical term referring to the apparent daily motion of stars in orbit around the Earth, caused by the Earths rotation around its axis. ... (2nd century BC - 1st century BC - 1st century - other centuries) The 1st century BC starts on January 1, 100 BC and ends on December 31, 1 BC. An alternative name for this century is the last century BC. (2nd millennium BC - 1st millennium BC - 1st millennium AD) Events The Roman...


The first modern orrery was built circa 1704 by George Graham. Graham gave the first model (or its design) to the celebrated instrument maker John Rowley of London to make a copy for Prince Eugene of Savoy. Rowley was commissioned to make another copy for his patron Charles Boyle, 4th Earl of Orrery, from which the device took its name. This model was presented to Charles' son John, later the 5th Earl. Events Building of the Students Monument in Aiud, Romania. ... George Graham (1674?-1751) was an English clockmaker and inventor and a member of the Royal Society. ... Prince Eugen von Savoyen in a contemporary painting François-Eugène, Prince of Savoy-Carignan, known as Prinz Eugen von Savoyen in German and Eugenio, Principe di Savoia in Italian (October 18, 1663 – April 24, 1736) was arguable the greatest general to serve the Habsburgs. ... Charles Boyle, 4th Earl of Orrery (July 28, 1674 - August 28, 1731), the second son of Roger, 2nd earl, was born at Chelsea. ...


Joseph Wright's picture "The Orrery" (c. 1766) [1] which hangs in Derby Museum and Art Gallery, features a group (three men, three children, and a lone woman) listening to a lecture by a 'natural philosopher'—the only light in the otherwise darkened room is apparently from the centre of the brass orrery, which, in the case, has rings that cause it to appear to be similar to an armillary sphere. Shoemaker John Fulton of Fenwick Ayrshire built three between 1823 and 1833 - the last is in Glasgow's Kelvingrove Art Gallery and Museum. An Experiment on a Bird in an Air Pump (1768). ... Categories: Stub | Derbyshire ... Natural philosophy is a term applied to the objective study of nature and the physical universe before the development of modern science. ... Armillary sphere An armillary sphere (also known as spherical astrolabe) is a model of the celestial sphere, invented by 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...


Explanation

Orreries are sometimes referred to as planetariums, although generally, planetariums are hemispherical theatres in which images of the night sky are projected onto an overhead surface. Orreries can range widely in size from hand-held to room-sized. // A planetarium is a theater built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. ...

A Philosopher Giving a Lecture on the Orrery by Joseph Wright of Derby

Orreries are usually not built to scale. Some fixed Solar system scale models have been built and are often many kilometres in size. An innovative concept is to have people play the role of the moving planets and other Solar system objects. Such a model, called a Human Orrery, has been laid out with precision at the Armagh Observatory. Image File history File links Wright_of_Derby,_The_Orrery. ... Image File history File links Wright_of_Derby,_The_Orrery. ... An Experiment on a Bird in an Air Pump (1768). ... Model ships and castle Freedom Plaza is a scale model depicting the layout of the Federal Triangle and part of the National Mall, Washington, DC; the diagonal slash across the layout depicts Pennsylvania Avenue A 1:5000 model of the entire Singapore City is found in the URA Gallery Museum... 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. ... Armagh Observatory is a modern astronomical research institute with a rich heritage, based in Armagh, Northern Ireland. ...


A normal mechanical clock could be used to produce an extremely simple orrery with the Sun in the centre, Earth on the minute hand and Jupiter on the hour hand; Earth would make 12 revolutions around the Sun for every 1 revolution of Jupiter. Note however that Jupiter's actual year is 11.86 Earth years long, so this particular example would lose accuracy rapidly. A real orrery would be more accurate and include more planets, and would perhaps make the planets rotate as well. 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. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ...


Many planetariums have a projection orrery, which projects onto the dome of the planetarium a Sun with either dots or small images of the planets. These usually are limited to the planets from Mercury to Saturn, although some include Uranus. The light sources for the planets are projected onto mirrors which are geared to a motor which drives the images on the dome. Typically the Earth will circle the Sun in one minute, while the other planets will complete an orbit in time periods proportional to their actual motion. Thus Venus, which takes 224.7 days to orbit the Sun, will take 0.7 minute to complete an orbit on an orrery, and Jupiter will take 11.86 minutes.


Some planetariums have taken advantage of this to use orreries to simulate planets and their moons. Thus Mercury orbits the Sun in 0.24 of an Earth year, while Phobos and Deimos orbit Mars in a similar 4:1 time ratio. Planetarium operators wishing to show this have placed a red cap on the Sun (to make it resemble Mars) and turned off all the planets but Mercury and Earth. Similar tricks can be used to show Pluto and its three moons. In Greek mythology, Phobos is one of the sons of Ares (Mars) and Aphrodite (Venus). ... Deimos, a Greek word for fear or terror, may refer to: Deimos (mythology), one of the sons of Ares and Aphrodite in Greek mythology. ...


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 digital computer) designed to calculate astronomical positions. ... Armillary sphere An armillary sphere (also known as spherical astrolabe) is a model of the celestial sphere, invented by 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... 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 planetarium is a theater 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. ... An ephemeris (plural: ephemerides) (from the Greek word ephemeros = daily) was, traditionally, a table providing the positions (given in a Cartesian coordinate system, or in right ascension and declination or, for astrologers, in longitude along the zodiacal ecliptic), of the Sun, the Moon, the planets, asteroids or comets in the... Tellurian is a variant spelling of tellurion, an instrument that depicts how day, night and the seasons are caused by the movement of the Earth on its axis and around the sun; it is similar to an orrery. ... Reess Cyclopaedia, or The New Cyclopaedia, or, Universal Dictionary of the Arts and Sciences was edited by Revd. ...

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