Difference between revisions of "Planetarium" - New World Encyclopedia

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[[Image:Adler fg02.jpg|thumb|300px|Adler Planetarium in Chicago, Illinois.]]
 
[[Image:Adler fg02.jpg|thumb|300px|Adler Planetarium in Chicago, Illinois.]]
 
[[Image:17 sierpnia 2006r. WPKiW 298.jpg|250px|thumb|Silesian Planetarium in Poland.]]
 
[[Image:17 sierpnia 2006r. WPKiW 298.jpg|250px|thumb|Silesian Planetarium in Poland.]]
  
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A '''planetarium''' (plural form: ''planetariums'' or ''planetaria'') is a [[theater]] built primarily for presenting educational and entertaining shows about [[astronomy]] and the night sky, or for training in [[celestial navigation]]. A dominant feature of most planetariums is the large, [[dome]]-shaped projection screen onto which scenes of [[star]]s, [[planet]]s, and other [[celestial object]]s can be made to appear and move realistically to simulate the complex 'motions of the heavens'.
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A '''planetarium''' (plural form: ''planetariums'' or ''planetaria'') is a [[theater]] built primarily for presenting educational and entertaining shows about [[astronomy]] and the night sky, or for training in [[celestial navigation]].<ref>Celestial navigation refers to navigation (particularly by sailors) using the positions of the [[Sun]], [[Moon]], [[planet]]s, or any of 57 "navigational stars" whose coordinates are tabulated in [[nautical almanac]]s.</ref> A dominant feature of most planetariums is the large, [[dome]]-shaped projection screen onto which scenes of [[star]]s, [[planet]]s, and other [[celestial object]]s can be made to appear and move realistically to simulate the complex 'motions of the heavens'.
  
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The celestial scenes can be created using a wide variety of technologies, such precision-engineered 'star balls' that combine optical and electro-mechanical technology, [[slide projector]], [[video]] and [[fulldome]] projector systems, and lasers. Whatever technologies are used, the objective is normally to link them together to provide an accurate relative motion of the sky. Typical systems can be set to display the sky at any point in time, past or present, and often to show the night sky as it would appear from any point of [[latitude]] on Earth.
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The celestial scenes can be created using a wide variety of technologies, such as precision-engineered 'star balls' that combine optical and electro-mechanical technology, [[slide projector]], [[video]] and [[fulldome]] projector systems, and lasers. Whatever the technologies used, they are combined to provide a display of relative motions of objects in the sky. Typical systems can be set to display the sky at any point in time, past or present, and often to show the night sky as it would appear from any point of [[latitude]] on Earth.
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Planetariums have become well-nigh ubiquitous, with some privately owned. A rough estimate is that in the United States there is one planetarium per 100,000 population, ranging in size from the [[Hayden Planetarium]]'s 20-meter dome seating 430 people, to three-meter inflatable portable domes where children sit on the floor. Such portable planetariums serve education programs outside of the permanent installations of [[museums]] and [[science center]]s.
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Planetariums have become nearly ubiquitous, and some are privately owned. According to a rough estimate, the United States has one planetarium per 100,000 population, ranging in size from the [[Hayden Planetarium]]'s 20-meter dome seating 430 people, to three-meter inflatable portable domes in which children sit on the floor. Such portable planetariums serve educational programs outside of the permanent installations of [[museums]] and [[science center]]s.
  
 
== Terminology ==
 
== Terminology ==
  
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* The term ''planetarium'' is sometimes used generically to describe other devices that illustrate the [[Solar System]], such as a computer simulation or an [[orrery]].
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* The term ''planetarium'' is sometimes used generically to describe other devices that illustrate the [[Solar System]], such as a computer simulation or an [[orrery]].<ref>An orrery is a mechanical device that illustrates the relative positions and motions of [[planet]]s and [[natural satellite|moon]]s in the [[Solar System]]. It is typically driven by a large [[clockwork]] mechanism, with a globe representing the [[Sun]] at the center.</ref>
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* The term ''planetarian'' is used to describe a member of the professional staff of a planetarium.
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* The term "planetarian" is used to describe a member of the professional staff of a planetarium.
 
* ''Planetarium software'' refers to a software application that renders a three-dimensional image of the sky onto a two-dimensional computer screen.
 
* ''Planetarium software'' refers to a software application that renders a three-dimensional image of the sky onto a two-dimensional computer screen.
  
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===Early===
 
===Early===
  
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[[Archimedes]] is attributed with possessing a primitive planetarium device that could predict the movements of the [[Sun]] and the [[Moon]] and the planets. The discovery of the [[Antikythera mechanism]] proved that such devices already existed during [[Ancient history|antiquity]]. [[Johannes Campanus]] (1220-1296) described a planetarium in his ''Theorica Planetarum'', and included instructions on how to build one. These devices would today usually be referred to as [[Orrery|orreries]] (named for the Earl of Orrery, a place in Ireland: an 18th century Earl of Orrery had one built). In fact, many planetariums today have what are called projection orreries, which project onto the dome a Sun with planets (usually limited to Mercury up to Saturn) going around it in something close to their correct relative periods.  
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[[Archimedes]] is attributed with possessing a primitive planetarium device that could predict the movements of the [[Sun]], [[Moon]], and [[planet]]s. The discovery of the [[Antikythera mechanism]] proved that such devices already existed during [[Ancient history|antiquity]]. [[Johannes Campanus]] (1220-1296) described a planetarium in his ''Theorica Planetarum,'' and included instructions on how to build one. These devices would today usually be referred to as [[Orrery|orreries]] (named for the Earl of Orrery, a place in Ireland: an eighteenth-century Earl of Orrery had one built). In fact, many planetariums today have what are called projection orreries, which project onto the dome a Sun with planets (usually limited to Mercury up to Saturn) going around it in something close to their correct relative periods.
  
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The small size of typical 18th century orreries limited their impact, and towards the end of that century a number of educators attempted some larger scale simulations of the heavens. The efforts of Adam Walker (1730-1821) and his sons are noteworthy in their attempts to fuse theatrical illusions with educational aspirations. Walker's Eidouranion was the heart of his public lectures or theatrical presentations. Walker's son describes this "Elaborate Machine" as "twenty feet high, and twenty-seven in diameter: it stands vertically before the spectators, and its globes are so large, that they are distinctly seen in the most distant parts of the Theatre. Every Planet and Satellite seems suspended in space, without any support; performing their annual and diurnal revolutions without any apparent cause." Other lecturers promoted their own devices: R E Lloyd advertised his Dioastrodoxon, or Grand Transparent Orrery, and by 1825 William Kitchener was offering his Ouranologia, which was 42 feet in diameter. These devices most probably sacrificed astronomical accuracy for crowd-pleasing spectacle and sensational and awe-provoking imagery.
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The small size of typical eighteenth-century orreries limited their impact, and toward the end of that century, a number of educators attempted some larger-scale simulations of the heavens. The efforts of Adam Walker (1730-1821) and his sons are noteworthy in their attempts to fuse theatrical illusions with educational aspirations. Walker's Eidouranion was the heart of his public lectures or theatrical presentations. Walker's son describes this "Elaborate Machine" as "twenty feet high, and twenty-seven in diameter: it stands vertically before the spectators, and its globes are so large, that they are distinctly seen in the most distant parts of the Theatre. Every Planet and Satellite seems suspended in space, without any support; performing their annual and diurnal revolutions without any apparent cause." Other lecturers promoted their own devices: R. E. Lloyd advertised his Dioastrodoxon, or Grand Transparent Orrery, and by 1825 William Kitchener was offering his Ouranologia, which was 42 feet in diameter. These devices most probably sacrificed astronomical accuracy for crowd-pleasing spectacle and sensational and awe-provoking imagery.
  
 
The oldest, still working planetarium can be found in the Dutch town [[Franeker]]. It was built by [[Eise Eisinga]] (1744-1828) in the livingroom of his house. It took Eisinga seven years to build his planetarium, which was completed in 1781.
 
The oldest, still working planetarium can be found in the Dutch town [[Franeker]]. It was built by [[Eise Eisinga]] (1744-1828) in the livingroom of his house. It took Eisinga seven years to build his planetarium, which was completed in 1781.
  
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In 1905 Oskar von Miller (1855-1934) of the Deutsches Museum in Munich commissioned updated versions of a geared orrery and planetarium from M Sendtner, and later worked with Franz Meyer, chief engineer at the Carl [[Zeiss]] optical works in Jena, on the largest mechanical planetarium ever constructed, capable of displaying both [[heliocentric]] and [[geocentric]] motion. This was displayed at the Deutsches Museum in 1924, construction work having been interrupted by the war. The planets travelled along overhead rails, powered by electric motors: the orbit of Saturn was 11.25 m in diameter. 180 stars were projected onto the wall by electric bulbs.
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In 1905, Oskar von Miller (1855-1934) of the Deutsches Museum in Munich commissioned updated versions of a geared orrery and planetarium from M Sendtner. He later worked with Franz Meyer, chief engineer at the Carl [[Zeiss]] optical works in Jena, on the largest mechanical planetarium ever constructed, capable of displaying both [[heliocentric]] and [[geocentric]] motion. It was displayed at the Deutsches Museum in 1924, construction work having been interrupted by the war. The planets traveled along overhead rails, powered by electric motors: the orbit of Saturn was 11.25 m in diameter. 180 stars were projected onto the wall by electric bulbs.
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While this was being constructed, von Miller was also working at the Zeiss factory with German astronomer Max Wolf, former director of the Baden Observatory in Heidelberg, on a new and novel design. The design was inspired by Wallace W. Atwood's work at the Chicago Academy of Sciences and by the ideas of Walther Bauersfeld at Zeiss. The result was a planetarium design that could generate all the necessary movements of the stars and planets inside the optical projector, and would be mounted centrally in a room, projecting images onto the white surface of a hemisphere. In August 1923, the first Zeiss planetarium projected images of the night sky onto the white plaster lining of a 16-m hemispherical concrete dome, erected on the roof of the Zeiss works.
  
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While this was being constructed, von Miller was also working at the Zeiss factory with German astronomer Max Wolf, former director of the Baden Observatory in Heidelberg, on a new and novel design, inspired by Wallace W Atwood's work at the Chicago Academy of Sciences and by the ideas of Walther Bauersfeld at Zeiss. The result was a planetarium design which would generate all the necessary movements of the stars and planets inside the optical projector, and would be mounted centrally in a room, projecting images onto the white surface of a hemisphere. In August 1923, the first Zeiss planetarium projected images of the night sky onto the white plaster lining of a 16 m hemispherical concrete dome, erected on the roof of the Zeiss works.
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Before [[World War II]], nearly all planetariums were built by [[Zeiss]]. The notable exceptions included one built by two brothers named Korkosz in [[Springfield, Massachusetts]], and another for the Rosicrucian AMORC order in [[San Jose, California]].
  
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Before [[World War II]] nearly all planetariums were built by [[Zeiss]], the only notable exceptions being one built by two brothers named Korkosz in [[Springfield, Massachusetts]], and another for the Rosicrucian AMORC order in [[San Jose, California]].
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===After World War II===
  
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===After WWII===
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When Germany was divided into East and West Germany after the war, the Zeiss firm was also split. Part remained in its traditional headquarters at [[Jena]], in [[East Germany]], and part migrated to [[West Germany]]. The designer of the first planetariums for Zeiss, [[Walther Bauersfeld]], remained in Jena until his death in 1959.
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When Germany was divided into East and West Germany after the war, the Zeiss firm was also split. Part remained in its traditional headquarters at [[Jena]], in [[East Germany]], and part migrated to [[West Germany]]. The designer of the first planetariums for Zeiss, [[Walther Bauersfeld]], remained in Jena until his death in 1959.
 
  
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The West German firm resumed making large planetariums in 1954, and the East German firm started making small planetariums a few years later. Meanwhile, the lack of planetarium manufacturers had led to several attempts at construction of unique models, such as one built by the [[California Academy of Sciences]] in [[Golden Gate Park]], [[San Francisco]], which operated 1952-2003. The Korkosz brothers built a large projector for the [[Boston Museum of Science]], which was unique in being the first (and for a very long time only) planetarium to project the planet [[Uranus]]. Most planetariums ignore Uranus as being at best marginally visible to the naked eye.
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The West German firm resumed making large planetariums in 1954, and the East German firm started making small planetariums a few years later. Meanwhile, the lack of planetarium manufacturers had led to several attempts at construction of unique models, such as one built by the [[California Academy of Sciences]] in [[Golden Gate Park]], [[San Francisco]], which operated from 1952 to 2003. The Korkosz brothers built a large projector for the [[Boston Museum of Science]], which was unique in being the first (and for a long time only) planetarium to project the planet [[Uranus]]. Most planetariums ignore Uranus as being at best marginally visible to the naked eye.
  
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A great boost to the popularity of the planetarium worldwide was provided by the [[Space Race]] of the 1950s and 60s when fears that the United States might miss out on the opportunities of the new frontier in space stimulated a massive program to install over 1,200 planetariums in U.S. high schools.
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Planetarium popularity got a worldwide boost by the [[Space Race]] of the 1950s and 60s. In particular, fears that the United States might miss out on the opportunities of the new frontier in space stimulated a massive program to install over 1,200 planetariums in U.S. high schools.
  
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[[Armand Spitz]] recognized that there was a viable market for small inexpensive planetariums. His first model, the Spitz A, was designed to project stars from a [[dodecahedron]], thus reducing machining expenses in creating a globe. Planets were not mechanized, but could be shifted by hand. Several models followed with various upgraded capabilities, until the A3P, which projected well over a thousand stars, had motorized motions for latitude change, daily motion, and annual motion for Sun, Moon (including phases), and planets. This model was installed in hundreds of high schools, colleges, and even small museums from 1964 to the 1980s.
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[[Armand Spitz]] recognized that there was a viable market for small, inexpensive planetariums. His first model, the Spitz A, was designed to project stars from a [[dodecahedron]], thus reducing machining expenses in creating a globe. Planets were not mechanized, but could be shifted by hand. Several models followed, with various upgraded capabilities, until the A3P, which projected well over a thousand stars, had motorized motions for latitude change, daily motion, and annual motion for the Sun, Moon (including phases), and planets. This model was installed in hundreds of high schools, colleges, and even small museums from 1964 to the 1980s.
  
 
[[Japan]] entered the planetarium manufacturing business in the 1960s, with [[Goto]] and [[Minolta]] both successfully marketing a number of different models. Goto was particularly successful when the Japanese Ministry of Education put one of their smallest models, the E-3 or E-5 (the numbers refer to the metric diameter of the dome) in every [[elementary school]] in Japan.
 
[[Japan]] entered the planetarium manufacturing business in the 1960s, with [[Goto]] and [[Minolta]] both successfully marketing a number of different models. Goto was particularly successful when the Japanese Ministry of Education put one of their smallest models, the E-3 or E-5 (the numbers refer to the metric diameter of the dome) in every [[elementary school]] in Japan.
  
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Phillip Stern, as former lecturer at [[New York City]]'s [[Hayden Planetarium]], had the idea of creating a small planetarium which could be programmed. His Apollo model was introduced in 1967 with a plastic program board, recorded lecture, and film strip. Unable to pay for this himself, Stern became the head of the planetarium division of [[Viewlex]], a mid-size audio-visual firm on [[Long Island]]. About thirty canned programs were created for various grade levels and the public, while operators could create their own or run the planetarium live. Purchasers of the Apollo were given their choice of two canned shows, and could purchase more. A few hundred were sold, but in the late 1970s Viewlex went bankrupt for reasons unrelated to the planetarium business.
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Phillip Stern, as former lecturer at [[New York City]]'s [[Hayden Planetarium]], had the idea of creating a small planetarium that could be programmed. His Apollo model was introduced in 1967 with a plastic program board, recorded lecture, and film strip. Unable to pay for this himself, Stern became the head of the planetarium division of [[Viewlex]], a mid-size audio-visual firm on [[Long Island]]. About thirty programs were prepared for various grade levels and the public, but operators could also create their own or run the planetarium live. Purchasers of the Apollo were given their choice of two canned shows, and could purchase more. A few hundred were sold, but in the late 1970s Viewlex went bankrupt for reasons unrelated to the planetarium business.
  
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During the 1970s, the [[OmniMax]] [[Film|movie]] system (now known as IMAX Dome) was conceived to operate on planetarium screens. More recently, some planetariums have re-branded themselves as ''dome theaters'', with broader offerings including wide-screen or "wraparound" films, [[fulldome|fulldome video]], and laser shows that combine music with laser-drawn patterns.
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During the 1970s, the [[OmniMax]] [[Film|movie]] system (now known as IMAX Dome) was conceived to operate on planetarium screens. More recently, some planetariums have re-branded themselves as ''dome theaters,'' with broader offerings including wide-screen or "wraparound" films, [[fulldome|fulldome video]], and laser shows that combine music with laser-drawn patterns.
  
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[[StarLab]] in [[Massachusetts]] offered the first easily portable planetarium in 1977 which projected stars, [[constellation]] figures from many [[mythologies]], celestial coordinate systems, and much else, from removable cylinders (Viewlex and others followed with their own portable versions).
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[[StarLab]] in [[Massachusetts]] offered the first easily portable planetarium in 1977. It projected stars, [[constellation]] figures from many [[mythologies]], celestial coordinate systems, and much else from removable cylinders. Viewlex and others followed with their own portable versions.
  
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When [[German reunification|Germany reunified]] in 1989, the two Zeiss firms did likewise, and expanded their offerings to cover many different size domes.
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After [[German reunification]] in 1989, the two Zeiss firms did likewise and expanded their offerings to cover different-sized domes.
  
 
===Computerized planetariums===
 
===Computerized planetariums===
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In 1983, [[Evans & Sutherland]] installed the first planetarium projector displaying computer graphics&mdash;the Digistar I projector used a [[vector gaphics|vector graphics system]] to display starfields as well as [[line art]].
 
In 1983, [[Evans & Sutherland]] installed the first planetarium projector displaying computer graphics&mdash;the Digistar I projector used a [[vector gaphics|vector graphics system]] to display starfields as well as [[line art]].
  
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The newest generation of planetariums, such as [[Evans & Sutherland]]'s [[Digistar 3]], RSA Cosmos's [[InSpace System]],<ref>[http://www.rsacosmos.com/index_us.htm RSA Cosmos] Retrieved December 18, 2007.</ref> [[Konica Minolta]]'s MEDIAGLOBE,<ref>[http://konicaminolta.com/kmpl/hard/mediaglobe.html MEDIAGLOBE] ''Konica Minolta''. Retrieved December 18, 2007.</ref> or [[Sky-Skan]]'s [[DigitalSky]], offer a fully [[digital]] projection system, using [[fulldome|fulldome video]] technology. This gives operators great flexibility in showing not only the modern night sky as visible from [[Earth]], but also any other images they choose, including the night sky as visible from points far distant in space and time.
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The newest generation of planetariums, such as [[Evans & Sutherland]]'s [[Digistar 3]], RSA Cosmos's [[InSpace System]],<ref>[http://www.rsacosmos.com/index_us.htm RSA Cosmos] Retrieved December 18, 2007.</ref> [[Konica Minolta]]'s MEDIAGLOBE,<ref>[http://konicaminolta.com/kmpl/hard/mediaglobe.html MEDIAGLOBE]. Konica Minolta. Retrieved December 18, 2007.</ref> or [[Sky-Skan]]'s [[DigitalSky]], offer a fully [[digital]] projection system, using [[fulldome|fulldome video]] technology. This gives operators great flexibility in showing not only the modern night sky as visible from [[Earth]], but also any other images they choose, including the night sky as visible from points far distant in space and time.
  
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A new generation of home planetariums was released in Japan by [[Takayuki Ohira]] in cooperation with [[Sega]]. Ohira has an international reputation for building portable planetariums used at exhibitions and events such as the Aichi World Expo in 2005. The Homestar Planetarium can be carried in a bag and is intended for home use; however, by projecting 10,000 stars on the ceiling, it is classified as semi-professional.<ref>[http://www.kilian-nakamura.com/blog-english/?p=115 Home Planetarium Trend: Sega Toys Homestar Planetarium Pro] ''CScout Japan''. Retrieved December 18, 2007.</ref>
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A new generation of home planetariums was released in Japan by [[Takayuki Ohira]] in cooperation with [[Sega]]. Ohira has an international reputation for building portable planetariums used at exhibitions and events such as the Aichi World Expo in 2005. The Homestar Planetarium can be carried in a bag and is intended for home use; however, by projecting 10,000 stars on the ceiling, it is classified as semi-professional.<ref>[http://www.kilian-nakamura.com/blog-english/?p=115 Home Planetarium Trend: Sega Toys Homestar Planetarium Pro] CScout Japan. Retrieved December 18, 2007.</ref>
  
 
== Planetarium technology ==
 
== Planetarium technology ==
 
=== Domes ===
 
=== Domes ===
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Planetarium domes range in size from 3 to 30 m in [[diameter]], accommodating from 1 to 500 people. They can be permanent or portable, depending on the application.  
 
Planetarium domes range in size from 3 to 30 m in [[diameter]], accommodating from 1 to 500 people. They can be permanent or portable, depending on the application.  
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* Portable [[inflatable]] domes can be inflated in minutes. Such domes are often used for touring planetariums visiting, for example, schools and community centres.
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* Portable [[inflatable]] domes can be inflated in minutes. Such domes are often used for touring planetariums visiting, for example, schools and community centers.
 
* Temporary structures using [[Glass-reinforced plastic]] (GRP) segments bolted together and mounted on a frame are possible. As they may take some hours to construct, they are more suitable for applications such as exhibition stands, where a dome will stay up for a period of at least several days.
 
* Temporary structures using [[Glass-reinforced plastic]] (GRP) segments bolted together and mounted on a frame are possible. As they may take some hours to construct, they are more suitable for applications such as exhibition stands, where a dome will stay up for a period of at least several days.
 
* Negative-pressure inflated domes are suitable in some semi-permanent situations. They use a fan to extract air from behind the dome surface, allowing [[atmospheric pressure]] to push it into the correct shape.
 
* Negative-pressure inflated domes are suitable in some semi-permanent situations. They use a fan to extract air from behind the dome surface, allowing [[atmospheric pressure]] to push it into the correct shape.
 
* Smaller permanent domes are frequently constructed from glass reinforced plastic. This is inexpensive but, as the projection surface reflects sound as well as light, the [[acoustics]] inside this type of dome can detract from its utility. Such a solid dome also presents issues connected with heating and ventilation in a large-audience planetarium, as air cannot pass through it.  
 
* Smaller permanent domes are frequently constructed from glass reinforced plastic. This is inexpensive but, as the projection surface reflects sound as well as light, the [[acoustics]] inside this type of dome can detract from its utility. Such a solid dome also presents issues connected with heating and ventilation in a large-audience planetarium, as air cannot pass through it.  
 
* Older planetarium domes were built using traditional construction materials and surfaced with [[plaster]]. This method is relatively expensive and suffers the same [[Acoustics|acoustic]] and [[Ventilation (architecture)|ventilation]] issues as GRP.
 
* Older planetarium domes were built using traditional construction materials and surfaced with [[plaster]]. This method is relatively expensive and suffers the same [[Acoustics|acoustic]] and [[Ventilation (architecture)|ventilation]] issues as GRP.
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* Most modern domes are built from thin [[aluminium]] sections with ribs providing a supporting structure behind. The use of aluminium makes it easy to perforate the dome with thousands of tiny holes. This reduces the reflectivity of sound back to the audience (providing better acoustic characteristics), lets a sound system project through the dome from behind (offering sound that seems to come from appropriate directions related to a show), and allows air circulation through the projection surface for climate control.
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* Most modern domes are built from thin [[aluminum]] sections with ribs providing a supporting structure behind. The use of aluminum makes it easy to perforate the dome with thousands of tiny holes. This reduces the reflectivity of sound back to the audience (providing better acoustic characteristics), lets a sound system project through the dome from behind (offering sound that seems to come from appropriate directions related to a show), and allows air circulation through the projection surface for climate control.
  
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The realism of the viewing experience in a planetarium depends significantly on the [[dynamic range]] of the image, i.e., the contrast between dark and light. This can be a challenge in any domed projection environment, because a bright image projected on one side of the dome will tend to reflect light across to the opposite side, "lifting" the [[black level]] there and so making the whole image look less realistic. Since traditional planetarium shows consisted mainly of small points of light (i.e., stars) on a black background, this was not a significant issue, but it became an issue as digital projection systems started to fill large portions of the dome with bright objects (e.g., large images of the sun in context). For this reason, modern planetarium domes are often not painted white but rather a mid grey colour, reducing reflection to perhaps 35-50%. This increases the perceived level of contrast.
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The realism of the viewing experience in a planetarium depends significantly on the [[dynamic range]] of the image, that is, the contrast between dark and light. This can be a challenge in any domed projection environment, because a bright image projected on one side of the dome will tend to reflect light across to the opposite side, "lifting" the [[black level]] there and so making the whole image look less realistic. Since traditional planetarium shows consisted mainly of small points of light (i.e., stars) on a black background, this was not a significant issue, but it became an issue as digital projection systems started to fill large portions of the dome with bright objects (e.g., large images of the sun in context). For this reason, modern planetarium domes are often not painted white but rather a mid gray color, reducing reflection to perhaps 35-50%. This increases the perceived level of contrast.
  
 
A major challenge in dome construction is to make seams as invisible as possible. Painting a dome after installation is a major task and, if done properly, the seams can be made almost to disappear.
 
A major challenge in dome construction is to make seams as invisible as possible. Painting a dome after installation is a major task and, if done properly, the seams can be made almost to disappear.
  
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Traditionally, planetarium domes were mounted horizontally, matching the natural horizon of the real night sky. However, because that configuration requires highly inclined chairs for comfortable viewing "straight up," increasingly domes are being built tilted from the horizontal by between 5 and 30 degrees to provide greater comfort. Tilted domes tend to create a favoured 'sweet spot' for optimum viewing, centrally about a third of the way up the dome from the lowest point. Tilted domes generally have seating arranged 'stadium-style' in straight, tiered rows; horizontal domes usually have seats in circular rows, arranged in concentric (facing center) or epicentric (facing front) arrays.
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Traditionally, planetarium domes were mounted horizontally, matching the natural horizon of the real night sky. However, because that configuration requires highly inclined chairs for comfortable viewing "straight up," increasingly domes are being built tilted from the horizontal by between 5 and 30 degrees to provide greater comfort. Tilted domes tend to create a favored 'sweet spot' for optimum viewing, centrally about a third of the way up the dome from the lowest point. Tilted domes generally have seating arranged 'stadium-style' in straight, tiered rows; horizontal domes usually have seats in circular rows, arranged in concentric (facing center) or epicentric (facing front) arrays.
  
 
Planetariums occasionally include controls such as buttons or [[joystick]]s in the arm-rests of seats to allow audience feedback that influences the show in [[Real-time computing|real time]].
 
Planetariums occasionally include controls such as buttons or [[joystick]]s in the arm-rests of seats to allow audience feedback that influences the show in [[Real-time computing|real time]].
  
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Often around the edge of the dome (the 'cove') are:-
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The edge of the dome (the 'cove') may have lighting to simulate the effect of twilight or urban [[light pollution]], or [[silhouette]] models of structures in the area round the planetarium building.
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* [[Silhouette]] models of geography or buildings like those in the area round the planetarium building.
 
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* Lighting to simulate the effect of twilight or urban [[light pollution]].
 
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* In one planetarium the horizon decor included a small model of a [[UFO]] flying.
 
  
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Traditionally, planetariums needed many [[Incandescent light bulb|incandescent lamps]] around the cove of the dome to help audience entry and exit, to simulate [[sunrise]] and [[sunset]], and to provide working light for dome cleaning. More recently, solid-state [[LED]] lighting has become available that significantly decreases power consumption and reduces the maintenance requirement as lamps no longer have to be changed on a regular basis.
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Traditionally, planetariums needed many [[Incandescent light bulb|incandescent lamps]] around the cove of the dome to help audience entry and exit, to simulate [[sunrise]] and [[sunset]], and to provide working light for dome cleaning. More recently, solid-state [[LED]] lighting has become available that significantly decreases power consumption and reduces the maintenance requirement, as the lamps no longer have to be changed on a regular basis.
  
 
===Traditional electromechanical/optical projectors===
 
===Traditional electromechanical/optical projectors===
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Traditional planetarium projection apparatus uses a hollow ball with a light inside, and a pinhole for each star, hence the name "star ball." With some of the brightest stars (e.g. [[Sirius]], [[Canopus]], [[Vega]]), the hole must be so big to let enough light through that there must be a small lens in the hole to focus the light to a sharp point on the dome.
 
  
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The star ball is usually mounted so it can rotate as a whole to simulate the Earth's daily rotation, and to change the simulated latitude on Earth. There is also usually a means of rotating to produce the effect of [[precession of the equinoxes]]. Often, one such ball is attached at its south [[ecliptic]] pole. In that case, the view cannot go so far south that any of the resulting blank area at the south is projected on the dome. Some star projectors have two balls at opposite ends of the projector like a [[dumbbell]]. In that case all stars can be shown and the view can go to either pole or anywhere between. But care must be taken that the projection fields of the two balls match where they meet or overlap.
+
Traditional planetarium projection apparatus uses a hollow ball with a light inside, and a pinhole for each star, hence the name "star ball." To show some of the brightest stars (such as [[Sirius]], [[Canopus]], [[Vega]]), the hole must be so big to let enough light through that there must be a small lens in the hole to focus the light to a sharp point on the dome.
 +
 
 +
The star ball is usually mounted such that it can rotate as a whole to simulate the Earth's daily rotation, and to change the simulated latitude on Earth. There is also usually a means of rotating to produce the effect of [[precession of the equinoxes]]. Often, one such ball is attached at its south [[ecliptic]] pole. In that case, the view cannot go so far south that any of the resulting blank area at the south is projected on the dome. Some star projectors have two balls at opposite ends of the projector, like a [[dumbbell]]. In that case, all stars can be shown and the view can go to either pole or anywhere between. But care must be taken that the projection fields of the two balls match where they meet or overlap.
  
 
Smaller planetarium projectors include a set of fixed stars, Sun, Moon, and planets, and various [[nebula]]e. Larger projectors also include [[comet]]s and a far greater selection of stars. Additional projectors can be added to show twilight around the outside of the screen (complete with city or country scenes) as well as the [[Milky Way]]. Others add coordinate lines and [[constellation]]s, photographic slides, [[laser]] displays, and other images.
 
Smaller planetarium projectors include a set of fixed stars, Sun, Moon, and planets, and various [[nebula]]e. Larger projectors also include [[comet]]s and a far greater selection of stars. Additional projectors can be added to show twilight around the outside of the screen (complete with city or country scenes) as well as the [[Milky Way]]. Others add coordinate lines and [[constellation]]s, photographic slides, [[laser]] displays, and other images.
  
−
Each planet is projected by a sharply focused [[spotlight]] that makes a spot of light on the dome. Planet projectors must have gearing to move their positioning and thereby simulate the planets' movements. These can be of these types:-
+
Each planet is projected by a sharply focused [[spotlight]] that makes a spot of light on the dome. Planet projectors must have gearing to move their positioning and thereby simulate the planets' movements. These can be of the following types:
−
*[[Copernican]]. The axis represents the Sun. The rotating piece that represents each planet carries a light that must be arranged and guided to swivel so it always faces towards the rotating piece that represents the Earth. This presents mechanical problems including:-
+
*[[Copernican]]. The axis represents the Sun. The rotating piece that represents each planet carries a light that must be arranged and guided to swivel so it always faces towards the rotating piece that represents the Earth. This presents mechanical problems, including:
 
::The planet lights must be powered by wires, which have to bend about as the planets rotate, and repeatedly bending copper wire tends to cause [[metal fatigue]].
 
::The planet lights must be powered by wires, which have to bend about as the planets rotate, and repeatedly bending copper wire tends to cause [[metal fatigue]].
 
::When a planet is at [[Opposition (astronomy)|opposition]] to the Earth, its light is liable to be blocked by the mechanism's central axle.
 
::When a planet is at [[Opposition (astronomy)|opposition]] to the Earth, its light is liable to be blocked by the mechanism's central axle.
−
:::(If the planet mechanism is set 180° rotated from reality, the lights are carried by the Earth and shines towards each planet, and the blocking risk happens at [[conjunction (astronomy)|conjunction]] with Earth.)
+
*[[Geocentric model|Ptolemaic]]. Here the central axis represents the Earth. Each planet light is on a mount that rotates only about the central axis, and is aimed by a guide steered by a deferent and an epicycle (or whatever the planetarium maker calls them). Here Ptolemy's number values must be revised to remove the daily rotation, which in a planetarium is catered for otherwise.
−
*[[Geocentric model|Ptolemaic]]. Here the central axis represents the Earth. Each planet light is on a mount which rotates only about the central axis, and is aimed by a guide which is steered by a deferent and an epicycle (or whatever the planetarium maker calls them). Here Ptolemy's number values must be revised to remove the daily rotation, which in a planetarium is catered for otherwise.
+
*Computer-controlled. Here all the planet lights are on mounts that rotate only about the central axis and are aimed by a [[computer]].
−
*Computer-controlled. Here all the planet lights are on mounts which rotate only about the central axis, and are aimed by a [[computer]].
 
  
−
Despite offering a good viewer experience, traditional star ball projectors suffer several inherent limitations. From a practical point of view, the low light levels require several minutes for the audience to [[Adaptation (eye)|"dark adapt"]] its eyesight. "Star ball" projection is limited in education terms by its inability to move beyond an earth-bound view of the night sky. Finally, a challenge for most traditional projectors is that the various overlaid projection systems are incapable of proper [[occultation]]. This means that a planet image projected on top of a star field (for example) will still show the stars shining through the planet image, degrading the quality of the viewing experience. For related reasons, some planetariums show stars below the horizon projecting on the walls below the dome or on the floor, or (with a bright star or a planet) shining in the eyes of someone in the audience.
+
Despite offering a good viewer experience, traditional star ball projectors have several inherent limitations. From a practical point of view, the low light levels require several minutes for members of the audience to [[Adaptation (eye)|"dark adapt"]] their eyesight. "Star ball" projection is limited in education terms by its inability to move beyond an earth-bound view of the night sky. Finally, a challenge for most traditional projectors is that the various overlaid projection systems are incapable of proper [[occultation]]. This means that a planet image projected on top of a star field (for example) will still show the stars shining through the planet image, degrading the quality of the viewing experience. For related reasons, some planetariums show stars below the horizon projecting on the walls below the dome or on the floor, or (with a bright star or a planet) shining in the eyes of someone in the audience.
  
−
However, the new breed of Optical-Mechanical projectors using fiber-optic technology to display the stars, show a much more realistic view of the sky, and are far superior to any digital star projector.
+
However, the new breed of Optical-Mechanical projectors, using fiber-optic technology to display the stars, show a much more realistic view of the sky.
  
 
===Digital projectors===
 
===Digital projectors===
−
[[Image:Zeiss_Universarium_MK_IX_at_gulbenkian_planetarium.JPG|thumb|200px|Zeiss Universarium IX, one of the most sophisticated projectors, circa 2005.]]
+
[[Image:Zeiss_Universarium_MK_IX_at_gulbenkian_planetarium.JPG|thumb|250px|Zeiss Universarium IX, one of the most sophisticated projectors, circa 2005.]]
  
−
An increasing number of planetariums are using [[digital]] technology to replace the entire system of interlinked projectors traditionally employed around a star ball to address some of their limitations. Digital planetarium manufacturers claim reduced maintenance costs and increased reliability from such systems compared with traditional "star balls" on the grounds that they employ few moving parts and do not generally require synchronization of movement across the dome between several separate systems. Some planetariums mix both traditional opto-mechanical projection and digital technologies on the same dome.
+
An increasing number of planetariums are using [[digital]] technology to replace the entire system of interlinked projectors traditionally employed around a star ball to address some of their limitations. Digital planetarium manufacturers claim reduced maintenance costs and increased reliability for such systems compared with traditional "star balls," noting that they employ few moving parts and do not generally require synchronization of movement across the dome between several separate systems. Some planetariums mix both traditional opto-mechanical projection and digital technologies on the same dome.
  
−
In a fully digital planetarium, the dome image is generated by a [[computer]] and then projected onto the dome using a variety of technologies including [[cathode ray tube]], [[LCD]], [[DLP]] or [[laser]] projectors. Sometimes a single projector mounted near the center of the dome is employed with a "fish eye lens" to spread the light over the whole dome surface, while in other configurations several projectors around the horizon of the dome are arranged to blend together seamlessly.
+
In a fully digital planetarium, the dome image is generated by a [[computer]] and then projected onto the dome using a variety of technologies, including [[cathode ray tube]], [[liquid crystal display]] (LCD), digital light processing ([[DLP]]), or [[laser]] projectors. Sometimes, a single projector mounted near the center of the dome is employed with a "fish eye lens" to spread the light over the whole dome surface. In other configurations, several projectors around the horizon of the dome are arranged to blend together seamlessly.
  
−
Digital projection systems all work by creating the image of the night sky as a large array of [[pixels]]. Generally speaking, the more pixels a system can display, the better the viewing experience. While the first generation of digital projectors were unable to generate enough pixels to match the image quality of the best traditional "star ball" projectors, high-end systems now offer a resolution that approaches the limit of human [[visual acuity]], making their images subjectively indistinguishable from the very best "star balls" to most eyes.
+
Digital projection systems all work by creating the image of the night sky as a large array of [[pixel]]s. Generally speaking, the more pixels a system can display, the better the viewing experience. Although the first generation of digital projectors were unable to generate enough pixels to match the image quality of the best traditional "star ball" projectors, high-end systems now offer a resolution that approaches the limit of human [[visual acuity]], making their images subjectively indistinguishable from the very best "star balls" to most eyes.
  
−
However, these digital star projectors do not show "pin-point" stars like one would actually see in the real sky. The colors of the stars are also not correct. Although the digital projectors are good for "traveling" through space, their ability to show a realistic star field is decades away. And although the digital manufacturers may say that the costs of maintenance are reduced, in reality, the maintenance costs of the digital and video units are significantly more than those of their optical-mechanical counterparts.
+
However, these digital star projectors do not show "pinpoint" stars as one would observe in the real sky. Also, the colors of the stars are not always correct. Although digital projectors are good for "traveling" through space, their ability to show a realistic star field is years away. Also, some say that maintenance costs of the digital and video units are significantly higher than those of their optical-mechanical counterparts.
  
−
LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetariums. [[LCOS]] and modified LCOS projectors have improved on LCD [[contrast ratio]]s while also eliminating the “screen door” effect of small gaps between LCD pixels. “Dark chip” DLP projectors improve on the standard DLP design and can offer relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors. As the technology matures and reduces in price, laser projection looks promising for dome projection as it offers bright images, large dynamic range and a very wide [[color space]].
+
LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetariums. [[LCOS]] (liquid crystal on silicon) and modified LCOS projectors have improved on LCD [[contrast ratio]]s, while also eliminating the “screen door” effect of small gaps between LCD pixels. “Dark chip” DLP projectors improve on the standard DLP design and can offer a relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors. As the technology matures and prices drop, laser projection seems promising for dome projection because it offers bright images, large dynamic range and a very wide [[color space]].
  
 
==Planetarium show content==
 
==Planetarium show content==
−
Worldwide, most planetariums provide shows to the general public. Traditionally, shows for these audiences with themes such as "What's in the sky tonight?," or shows which pick up on topical issues such as a religious festival (often the [[Christmas star]]) linked to the night sky, have been popular. Pre-recorded and live presentation formats are possible. Live format are preferred by many venues (despite the increased expense) because a live expert presenter can answer on the spot questions raised by the audience.
 
  
−
Since the early 1990s, fully featured [[3-D computer graphics|3-D]] digital planetariums have added an extra degree of freedom to a presenter giving a show because they allow simulation of the view from any point in space, not only the earth-bound view which we are most familiar with. This new [[virtual reality]] capability to travel through the universe provides important [[education]]al benefits because it vividly conveys that space has depth, helping audiences to leave behind the ancient misconception that the stars are stuck on the inside of a giant [[celestial sphere]] and instead to understand the true layout of the [[solar system]] and beyond. For example, a planetarium can now 'fly' the audience towards one of the familiar constellations such as [[Orion (constellation)|Orion]], revealing that the stars which appear to make up a co-ordinated shape from our earth-bound viewpoint are at vastly different distances from Earth and so not connected, except in human imagination and [[mythology]]. For especially visual or [[kinesthetic|spatially-aware]] people, this experience can be more educationally beneficial than other demonstrations.
+
Worldwide, most planetariums provide shows to the general public. Traditionally, shows for these audiences with themes such as "What's in the sky tonight?," or shows that pick up on topical issues such as a religious festival (often the [[Christmas star]]) linked to the night sky, have been popular. Pre-recorded and live presentation formats are possible. Live formats are preferred by many venues (despite the increased expense) because members of the audience can get immediate answers from an expert presenter.
  
−
Music is an important element to fill out the experience of a good planetarium show, often featuring forms of [[space-themed music]], or music from the genres of [[space music]], [[space rock]], or [[classical music]].
+
Since the early 1990s, fully featured [[3-D computer graphics|3-D]] digital planetariums have added an extra degree of freedom to a presenter because they allow simulation of the view from any point in space, not just the earth-bound view that we are most familiar with. This new [[virtual reality]] capability to travel through the universe provides important [[education]]al benefits: It vividly conveys that space has depth, helping audiences leave behind the ancient misconception that the stars are stuck on the inside of a giant [[celestial sphere]], and to understand the true layout of the [[Solar System]] and beyond.
 +
 
 +
For example, a planetarium can now 'fly' the audience toward one of the familiar constellations such as [[Orion (constellation)|Orion]], revealing that the stars that appear to make up a coordinated shape from our earth-bound viewpoint are at vastly different distances from Earth and so not connected, except in human imagination and [[mythology]]. For especially visual or [[kinesthetic|spatially aware]] people, this experience can be more educationally beneficial than other demonstrations.
 +
 
 +
Music is an important element to fill out the experience of a good planetarium show, often featuring forms of [[space-themed music]], or music from the genres of [[space music]], [[space rock]], or [[classical music]].
  
 
==Images of planetariums==
 
==Images of planetariums==
Line 134: Line 136:
 
==Images of planetarium projectors==
 
==Images of planetarium projectors==
 
<gallery>
 
<gallery>
−
Image:Zeiss_Universarium_MK_IX_at_gulbenkian_planetarium.JPG|Zeiss Universarium IX, one of the most sophisticated projectors circa 2005
 
 
Image:Planetarium_awi_hg.jpg|Smallest Zeiss projector ever built
 
Image:Planetarium_awi_hg.jpg|Smallest Zeiss projector ever built
 
Image:Zeiss_Modell_VI_1968_fg01.jpg|Zeiss Model VI, 1968
 
Image:Zeiss_Modell_VI_1968_fg01.jpg|Zeiss Model VI, 1968
−
Image:ZeissPlanetariumProjector_MontrealPlanetarium.jpg|A 1960's era electromechanical East German-made Zeiss projector
+
Image:ZeissPlanetariumProjector_MontrealPlanetarium.jpg|A 1960s era electromechanical projector made by Zeiss of East Germany.
 
</gallery>
 
</gallery>
−
 
−
== Notable planetariums ==
 
−
 
−
*[[Australia]]:
 
−
** [http://www.brisbane.qld.gov.au/planetarium/ Sir Thomas Brisbane Planetarium] [[Brisbane]], [[Australia]]
 
−
 
−
*[[Burma]]: [[Planetarium (Myanmar)]]
 
−
*[[Canada]]:
 
−
**[[Manitoba Museum]], [[Winnipeg]], [[Manitoba]], [[Canada]]
 
−
**[[Montreal Planetarium]], [[Montreal]], [[Quebec]], [[Canada]]
 
−
**[[H.R. MacMillan Space Centre]], [[Vancouver]], [[Canada]]
 
−
**[[McLaughlin Planetarium]], [[Toronto]], [[Ontario]], [[Canada]]. Closed 1995, building still extant.
 
−
 
−
*[[Brazil]]:
 
−
**[http://www.rio.rj.gov.br/planetario The Rio de Janeiro Planetarium Foundation], [[Rio de Janeiro]]
 
−
**[[Ibirapuera]] Planetarium, [[São Paulo]]
 
−
**[[Carmo]] Planetarium, [[São Paulo]]
 
−
**[http://www.asterdomus.com.br/principal_5_4.htm The AsterDomus Planetarium site list of Brasilians planetaria]
 
−
 
−
*[[European Union]]:
 
−
**[http://www.tycho.dk/in_english Tycho Brahe Planetarium], [[Copenhagen]], [[Denmark]]
 
−
**[[Heureka]] Planetarium, [[Vantaa]], [[Finland]]
 
−
**[[Särkänniemi]] Planetarium, [[Tampere]], [[Finland]]
 
−
**[http://www.cite-espace.com Cite de l'espace],[[Toulouse]], [[France]]
 
−
**[http://www.planetarium-galilee.com/ Planetarium Galilee], [[Montpellier]], France
 
−
**[http://www.planetarium-nuernberg.de Nicolaus Copernicus Planetarium], [[Nuremberg]], [[Germany]]
 
−
**[http://www.s-planetarium.de Sparkassen-Planetarium Augsburg], [[Augsburg]], [[Germany]]
 
−
**[http://www.planetarium-hamburg.de Hamburg Planetarium], [[Hamburg]], [[Germany]]
 
−
**[http://www.planetarium-bochum.info Bochum Planetarium], [[Bochum]], Germany
 
−
**[http://www.planetarium-stuttgart.de Carl-Zeiss-Planetarium], [[Stuttgart]], Germany
 
−
**[http://www.eugenfound.edu.gr Athens Planetarium], [[Athens]], [[Greece]]
 
−
**[http://www.planetarium.hu/ TIT Budapesti Planetárium], [[Budapest]], [[Hungary]]
 
−
**[http://www.planetariodanti.pg.it "Ignazio Danti" Planetarium], [[Perugia]], [[Italy]]
 
−
**[http://www.to.astro.it Osservatorio Astronomico Di Torino], [[Turin]], [[Italy]]
 
−
**[http://www.artis.nl/international/cultural/4.html Artis Planetarium], [[Amsterdam]]
 
−
**[[Silesian Planetarium]], [[Katowice]], [[Poland]]
 
−
**[http://planetario.online.pt/entrada.asp Lisbon Gulbenkian Planetarium], [[Lisbon]], [[Portugal]]
 
−
**[[Armagh Planetarium]], [http://www.armaghplanet.com], [[Armagh]], [[Northern Ireland]]
 
−
**[[London Planetarium]], [[Marylebone Road]], [[London]] (part of [[Madame Tussaud's]]), closed in 2006.
 
−
**[http://www.glasgowsciencecentre.org/ Glasgow Science Centre], [[Glasgow]], [[Scotland]]
 
−
**[[Jodrell Bank]], closed in 2003
 
−
**[[National Space Centre]] in [[Leicester]], only used as a [[movie theatre|cinema]]
 
−
**[[Peter Harrison Planetarium]], [[National Maritime Museum]], [[London]], [[England]]; Opened in 2007
 
−
**[http://www.thinktank.ac/explore/futures/planetarium.htm Thinktank Museum], [[Birmingham]], [[England]]
 
−
**[[Yorkshire Planetarium ]], [[Harewood House]], [[Leeds]], [[England]]; Opened in 2007
 
−
**[http://www.multimeios.pt/ Espinho Planetarium, Navegar Foundation], [[Espinho]], [[Portugal]]
 
−
 
−
*[[USA]]:
 
−
**[[Abrams Planetarium]], [[Michigan State University]], [[East Lansing, Michigan]], [[Michigan]]
 
−
**[[Adler Planetarium]], [[Chicago]], [[Illinois]]
 
−
**[[Alden Planetarium]], [[EcoTarium]], [[Worcester]], [[Massachusetts]]
 
−
**Albert Einstein Planetarium, [[National Air and Space Museum]], [[Smithsonian Institution]], [[Washington, DC]]
 
−
**[[Alexander Brest Planetarium]], [[Museum of Science & History]], [[Jacksonville, Florida]]
 
−
**[[Arthur Storer]] Planetarium, [[Prince Frederick, Maryland]], named after the first astronomer in the American Colonies and the original namesake of [[Halleys Comet]].
 
−
**[[Buhl Digital Dome]], [[Carnegie Science Center]], [[Pittsburgh, Pennsylvania]], [http://www.carnegiesciencecenter.org/explore/buhl_history.html]
 
−
**[[BCC Planetarium & Observatory]], [[Cocoa, Florida|Cocoa]], [[Florida]] | [http://www.brevard.cc.fl.us/planet/ web]
 
−
**[[Cernan Earth and Space Center]], [[Triton College]], [[River Grove]], [[Illinois]]
 
−
**[[Clark Planetarium]], [[Salt Lake City]], [[Utah]]
 
−
**[[CyberSphere Digital Theater]], [[Dickson, TN]], [http://www.rcenter.org/ The Renaissance Center]
 
−
**[http://www.detroitsciencecenter.org Dassault Systemes Planetarium] at the [[New Detroit Science Center]]
 
−
**[http://www.mdsci.org/shows/planetarium.html Davis Planetarium] at the [[Maryland Science Center]]
 
−
**[http://www.delta.edu/planet Delta College Planetarium & Learning Center] Bay City, MI
 
−
**[http://www.newarkmuseum.org/planetarium Dreyfuss Planetarium] at [[The Newark Museum]], Newark, NJ
 
−
**EpiSphere at the Aerospace Education Center, [[Little Rock, Arkansas]] - first single-projector digital planetarium; one of only three so far
 
−
**[[Fels]] Planetarium at the [[Franklin Institute]] ([[Philadelphia, Pennsylvania|Philadelphia]], [[Pennsylvania]])
 
−
**[[Gheen's Science Hall & Rauch Planetarium]], [[University of Louisville]], [[Louisville, Kentucky]], [http://www.louisville.edu/planetarium/]
 
−
**[[George Alden Planetarium]] at the [[Ecotarium]] (Worcester, Massachusetts)
 
−
**[[Griffith Observatory]], [[Los Angeles, California]]
 
−
**Charles Hayden Planetarium at the [[Museum of Science, Boston|Museum of Science]], ([[Boston, Massachusetts|Boston]], [[Massachusetts]])
 
−
**Framingham State College Planetarium Framingham, Massachusetts
 
−
**[[Hayden Planetarium]], [[American Museum of Natural History]], [[New York, NY]]
 
−
**Burke Baker Planetarium at the [[Houston Museum of Natural Science]], [[Houston, TX]]
 
−
**[http://www.lasm.org Irene W. Pennington Planetarium], [[Baton Rouge]], [[Louisiana]]
 
−
**Kirkpatrick Planetarium at the [[Omniplex Science Museum]], [[Oklahoma City]], [[Oklahoma]]
 
−
**[http://www.lodestar.unm.edu Lodestar Astronomy Center], [[Albuquerque]], [[New Mexico]]
 
−
**[http://www.longwayplanetarium.com/ Longway Planetarium], [[Flint]], [[Michigan]]
 
−
**[[Miami Museum of Science & Planetarium]], [[Miami, Florida]], opened in 1966.
 
−
**[[Minneapolis Planetarium]], [[Minneapolis Public Library]], [[Minneapolis, Minnesota]]. Until the  MPL's central branch was closed and demolished in 2002, the Minneapolis Planetarium had the oldest extant projector (installed in 1954); the fate of that projector is unknown. A new public library opened in its place in 2006, and a new planetarium with modern digital projection capabilities is planned to be added to the building in 2009.
 
−
**[http://www.moreheadplanetarium.org Morehead Planetarium and Science Center] at the [[University of North Carolina at Chapel Hill]] is the first planetarium that was built on a U.S. college campus.
 
−
**[[Ott Planetarium]] at [[Weber State University]] in [[Ogden, Utah]].  Produces original content for small planetaria with an all-undergraduate production team.
 
−
**Omnisphere Theater, [[Coca-Cola Space Science Center]], [[Columbus State University]], [[Columbus, Georgia]]
 
−
**[[Strasenburgh Planetarium]], in Rochester, NY, which is part of the Rochester Museum and Science Center
 
−
**[http://www.yhc.edu/1764.aspx Rollins Planetarium], [[Young Harris College]], [[Young Harris, Georgia]]
 
−
**[[Rosicrucian Egyptian Museum]], in [[San Jose, California]], which has a purpose-built planetarium rendered in an Ancient Egyptian architectural style
 
−
**[http://www.cmnh.org/site/AtTheMuseum_PlanetariumandObservatory_ShafranPlanetarium.aspx Shafan Planetarium] at the [http://www.cmnh.org Cleveland Museum of Natural History], Cleveland, Ohio
 
−
**[[W.A. Gayle Planetarium]], [[Montgomery, Alabama]]
 
−
 
−
To give some idea of the number of planetariums and the difficulty in trying to list all, over fifty have been documented as having been sold to various locations in the five boroughs of New York City, ranging from one in Manhattan with a 76-foot dome that is used as a light effect in a disco to a two elementary schools in the Bronx with 12-foot domes. There are also many portable planetariums, including two on Staten Island that are privately owned, plus one in an Intermediate School. A little known model, the Aquarian, was made in the 1970s. Only about twenty are believed to have been sold, but only one of these has been tracked down, stored under the auditorium floor of an elementary school in [[Queens]].
 
−
 
−
*Other parts of the world:
 
−
**[http://planetarium-kharkov.org "Kharkov planetarium" Planetarium], [[Ukraine]]
 
−
**[[Nehru Planetarium]]s, one each at [[Mumbai]], [[New Delhi]], and [[Bangalore]], [[Leo Planetaria]][http://www.leoplanetaria.com] at New Delhi,  [[India]]
 
−
**[[M. P. Birla Planetarium Leo Planetaria]] at [[Kolkata]], [[INDIA]]
 
−
**[http://www.planetarioalfa.org.mx/ Planetario Alfa] [[Monterrey]], [[México]]
 
−
**[[Ehime Prefectural Science Museum]], [[Ehime Prefecture|Ehime]], [[Japan]] has one of largest domes in the world (30m in diameter)
 
−
**[http://www.ksm.or.jp Kobe Science Museum], [[Kobe]], [[Japan]]
 
−
**[http://www.tam.gov.tw/ Taipei Astronomical Museum], [[Taipei]], [[Taiwan]]
 
−
**[[Hong Kong Space Museum]], [[Kowloon]], [[Hong Kong]], [[China]]
 
−
**[http://www.planetarium-sarawak.org Kuching Planetarium], Sarawak, Malaysia
 
−
**Planetarium Sultan Iskandar Malaysia[http://www.planetarium-sarawak.org]
 
−
**PIA planetarium, [[Karachi]] and [[Lahore]]
 
−
**Johannesburg Planetarium[http://www.wits.ac.za/www/PlacesOfInterest/Planetarium]
 
−
**[http://www.planetariochile.cl/ Planetario USACH [[University of Santiago, Chile|University of Santiago]]], [[Santiago, Chile|Santiago]], [[Chile]]
 
−
**[http://www.planetario.gov.ar Planetario Galileo Galilei], [[Buenos Aires]], [[Argentina]]
 
−
**[Planetario "Simón Bolívar], [[Maracaibo]], [[Venezuela]]
 
−
**[Planetario Humtbold], [[Caracas]], [[Venezuela]]
 
−
**[http://www.planetario.ucr.ac.cr/ Planetario Ciudad de San José] [[San José, Costa Rica|San José]], [[Costa Rica]]
 
−
**[http://www.planetario.ipn.mx/ Planetario Instituto Politecnico Nacional] [[Mexico D.F., Mexico|Mexico D.F.]], [[Mexico]]
 
−
{{listdev}}
 
  
 
== See also ==
 
== See also ==
Line 272: Line 164:
  
 
== External links ==
 
== External links ==
 +
All links retrieved November 24, 2022.
  
−
* [http://www.seds.org/billa/astrosoftware.html List of Planetarium Software]
+
* [http://www.ips-planetarium.org International Planetarium Society].  
−
* [http://www.ips-planetarium.org International Planetarium Society]
+
* [http://www.skyskan.com Sky-Skan, Inc. - Digital planetarium system manufacturer].
−
* [http://www.astromedia.de/ Orrery and planetarium cardboard kits (Germany)]
+
* [http://www.rsacosmos.com/index_us.htm RSA Cosmos manufacturer of Digital and Optical Planetarium].  
−
* [http://www.asterdomus.com.br AsterDomus Planetarium site (portuguese) - planetarium manufacturer]
 
−
* [http://lochnessproductions.com/lpco/lpco.html Loch Ness Productions list of planetariums worldwide]
 
−
* [http://www.planetariumsclub.de/ PlanetariumsClub - German site for various topics on planetaria]
 
−
* [http://www.skyskan.com Sky-Skan, Inc. - Digital planetarium system manufacturer]
 
−
* [http://www.platial.com/hundredflowers/map/3555#Planetaria_and_Observatories Map: Planetaria and Observatories]
 
−
* [http://www.rsacosmos.com/index_us.htm RSA Cosmos manufacturer of Digital and Optical Planetarium]
 
−
* [http://www.kilian-nakamura.com/blog-english/?p=115 Article about Sega Homestar Planetarium]
 
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]

Latest revision as of 07:49, 24 November 2022

Adler Planetarium in Chicago, Illinois.
Silesian Planetarium in Poland.

A planetarium (plural form: planetariums or planetaria) is a theater built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation.[1] A dominant feature of most planetariums is the large, dome-shaped projection screen onto which scenes of stars, planets, and other celestial objects can be made to appear and move realistically to simulate the complex 'motions of the heavens'.

The celestial scenes can be created using a wide variety of technologies, such as precision-engineered 'star balls' that combine optical and electro-mechanical technology, slide projector, video and fulldome projector systems, and lasers. Whatever the technologies used, they are combined to provide a display of relative motions of objects in the sky. Typical systems can be set to display the sky at any point in time, past or present, and often to show the night sky as it would appear from any point of latitude on Earth.

Planetariums have become nearly ubiquitous, and some are privately owned. According to a rough estimate, the United States has one planetarium per 100,000 population, ranging in size from the Hayden Planetarium's 20-meter dome seating 430 people, to three-meter inflatable portable domes in which children sit on the floor. Such portable planetariums serve educational programs outside of the permanent installations of museums and science centers.

Terminology

  • The term planetarium is sometimes used generically to describe other devices that illustrate the Solar System, such as a computer simulation or an orrery.[2]
  • The term "planetarian" is used to describe a member of the professional staff of a planetarium.
  • Planetarium software refers to a software application that renders a three-dimensional image of the sky onto a two-dimensional computer screen.

History

Early

Archimedes is attributed with possessing a primitive planetarium device that could predict the movements of the Sun, Moon, and planets. The discovery of the Antikythera mechanism proved that such devices already existed during antiquity. Johannes Campanus (1220-1296) described a planetarium in his Theorica Planetarum, and included instructions on how to build one. These devices would today usually be referred to as orreries (named for the Earl of Orrery, a place in Ireland: an eighteenth-century Earl of Orrery had one built). In fact, many planetariums today have what are called projection orreries, which project onto the dome a Sun with planets (usually limited to Mercury up to Saturn) going around it in something close to their correct relative periods.

The small size of typical eighteenth-century orreries limited their impact, and toward the end of that century, a number of educators attempted some larger-scale simulations of the heavens. The efforts of Adam Walker (1730-1821) and his sons are noteworthy in their attempts to fuse theatrical illusions with educational aspirations. Walker's Eidouranion was the heart of his public lectures or theatrical presentations. Walker's son describes this "Elaborate Machine" as "twenty feet high, and twenty-seven in diameter: it stands vertically before the spectators, and its globes are so large, that they are distinctly seen in the most distant parts of the Theatre. Every Planet and Satellite seems suspended in space, without any support; performing their annual and diurnal revolutions without any apparent cause." Other lecturers promoted their own devices: R. E. Lloyd advertised his Dioastrodoxon, or Grand Transparent Orrery, and by 1825 William Kitchener was offering his Ouranologia, which was 42 feet in diameter. These devices most probably sacrificed astronomical accuracy for crowd-pleasing spectacle and sensational and awe-provoking imagery.

The oldest, still working planetarium can be found in the Dutch town Franeker. It was built by Eise Eisinga (1744-1828) in the livingroom of his house. It took Eisinga seven years to build his planetarium, which was completed in 1781.

In 1905, Oskar von Miller (1855-1934) of the Deutsches Museum in Munich commissioned updated versions of a geared orrery and planetarium from M Sendtner. He later worked with Franz Meyer, chief engineer at the Carl Zeiss optical works in Jena, on the largest mechanical planetarium ever constructed, capable of displaying both heliocentric and geocentric motion. It was displayed at the Deutsches Museum in 1924, construction work having been interrupted by the war. The planets traveled along overhead rails, powered by electric motors: the orbit of Saturn was 11.25 m in diameter. 180 stars were projected onto the wall by electric bulbs.

While this was being constructed, von Miller was also working at the Zeiss factory with German astronomer Max Wolf, former director of the Baden Observatory in Heidelberg, on a new and novel design. The design was inspired by Wallace W. Atwood's work at the Chicago Academy of Sciences and by the ideas of Walther Bauersfeld at Zeiss. The result was a planetarium design that could generate all the necessary movements of the stars and planets inside the optical projector, and would be mounted centrally in a room, projecting images onto the white surface of a hemisphere. In August 1923, the first Zeiss planetarium projected images of the night sky onto the white plaster lining of a 16-m hemispherical concrete dome, erected on the roof of the Zeiss works.

Before World War II, nearly all planetariums were built by Zeiss. The notable exceptions included one built by two brothers named Korkosz in Springfield, Massachusetts, and another for the Rosicrucian AMORC order in San Jose, California.

After World War II

When Germany was divided into East and West Germany after the war, the Zeiss firm was also split. Part remained in its traditional headquarters at Jena, in East Germany, and part migrated to West Germany. The designer of the first planetariums for Zeiss, Walther Bauersfeld, remained in Jena until his death in 1959.

The West German firm resumed making large planetariums in 1954, and the East German firm started making small planetariums a few years later. Meanwhile, the lack of planetarium manufacturers had led to several attempts at construction of unique models, such as one built by the California Academy of Sciences in Golden Gate Park, San Francisco, which operated from 1952 to 2003. The Korkosz brothers built a large projector for the Boston Museum of Science, which was unique in being the first (and for a long time only) planetarium to project the planet Uranus. Most planetariums ignore Uranus as being at best marginally visible to the naked eye.

Planetarium popularity got a worldwide boost by the Space Race of the 1950s and 60s. In particular, fears that the United States might miss out on the opportunities of the new frontier in space stimulated a massive program to install over 1,200 planetariums in U.S. high schools.

Armand Spitz recognized that there was a viable market for small, inexpensive planetariums. His first model, the Spitz A, was designed to project stars from a dodecahedron, thus reducing machining expenses in creating a globe. Planets were not mechanized, but could be shifted by hand. Several models followed, with various upgraded capabilities, until the A3P, which projected well over a thousand stars, had motorized motions for latitude change, daily motion, and annual motion for the Sun, Moon (including phases), and planets. This model was installed in hundreds of high schools, colleges, and even small museums from 1964 to the 1980s.

Japan entered the planetarium manufacturing business in the 1960s, with Goto and Minolta both successfully marketing a number of different models. Goto was particularly successful when the Japanese Ministry of Education put one of their smallest models, the E-3 or E-5 (the numbers refer to the metric diameter of the dome) in every elementary school in Japan.

Phillip Stern, as former lecturer at New York City's Hayden Planetarium, had the idea of creating a small planetarium that could be programmed. His Apollo model was introduced in 1967 with a plastic program board, recorded lecture, and film strip. Unable to pay for this himself, Stern became the head of the planetarium division of Viewlex, a mid-size audio-visual firm on Long Island. About thirty programs were prepared for various grade levels and the public, but operators could also create their own or run the planetarium live. Purchasers of the Apollo were given their choice of two canned shows, and could purchase more. A few hundred were sold, but in the late 1970s Viewlex went bankrupt for reasons unrelated to the planetarium business.

During the 1970s, the OmniMax movie system (now known as IMAX Dome) was conceived to operate on planetarium screens. More recently, some planetariums have re-branded themselves as dome theaters, with broader offerings including wide-screen or "wraparound" films, fulldome video, and laser shows that combine music with laser-drawn patterns.

StarLab in Massachusetts offered the first easily portable planetarium in 1977. It projected stars, constellation figures from many mythologies, celestial coordinate systems, and much else from removable cylinders. Viewlex and others followed with their own portable versions.

After German reunification in 1989, the two Zeiss firms did likewise and expanded their offerings to cover different-sized domes.

Computerized planetariums

In 1983, Evans & Sutherland installed the first planetarium projector displaying computer graphics—the Digistar I projector used a vector graphics system to display starfields as well as line art.

The newest generation of planetariums, such as Evans & Sutherland's Digistar 3, RSA Cosmos's InSpace System,[3] Konica Minolta's MEDIAGLOBE,[4] or Sky-Skan's DigitalSky, offer a fully digital projection system, using fulldome video technology. This gives operators great flexibility in showing not only the modern night sky as visible from Earth, but also any other images they choose, including the night sky as visible from points far distant in space and time.

A new generation of home planetariums was released in Japan by Takayuki Ohira in cooperation with Sega. Ohira has an international reputation for building portable planetariums used at exhibitions and events such as the Aichi World Expo in 2005. The Homestar Planetarium can be carried in a bag and is intended for home use; however, by projecting 10,000 stars on the ceiling, it is classified as semi-professional.[5]

Planetarium technology

Domes

Planetarium domes range in size from 3 to 30 m in diameter, accommodating from 1 to 500 people. They can be permanent or portable, depending on the application.

  • Portable inflatable domes can be inflated in minutes. Such domes are often used for touring planetariums visiting, for example, schools and community centers.
  • Temporary structures using Glass-reinforced plastic (GRP) segments bolted together and mounted on a frame are possible. As they may take some hours to construct, they are more suitable for applications such as exhibition stands, where a dome will stay up for a period of at least several days.
  • Negative-pressure inflated domes are suitable in some semi-permanent situations. They use a fan to extract air from behind the dome surface, allowing atmospheric pressure to push it into the correct shape.
  • Smaller permanent domes are frequently constructed from glass reinforced plastic. This is inexpensive but, as the projection surface reflects sound as well as light, the acoustics inside this type of dome can detract from its utility. Such a solid dome also presents issues connected with heating and ventilation in a large-audience planetarium, as air cannot pass through it.
  • Older planetarium domes were built using traditional construction materials and surfaced with plaster. This method is relatively expensive and suffers the same acoustic and ventilation issues as GRP.
  • Most modern domes are built from thin aluminum sections with ribs providing a supporting structure behind. The use of aluminum makes it easy to perforate the dome with thousands of tiny holes. This reduces the reflectivity of sound back to the audience (providing better acoustic characteristics), lets a sound system project through the dome from behind (offering sound that seems to come from appropriate directions related to a show), and allows air circulation through the projection surface for climate control.

The realism of the viewing experience in a planetarium depends significantly on the dynamic range of the image, that is, the contrast between dark and light. This can be a challenge in any domed projection environment, because a bright image projected on one side of the dome will tend to reflect light across to the opposite side, "lifting" the black level there and so making the whole image look less realistic. Since traditional planetarium shows consisted mainly of small points of light (i.e., stars) on a black background, this was not a significant issue, but it became an issue as digital projection systems started to fill large portions of the dome with bright objects (e.g., large images of the sun in context). For this reason, modern planetarium domes are often not painted white but rather a mid gray color, reducing reflection to perhaps 35-50%. This increases the perceived level of contrast.

A major challenge in dome construction is to make seams as invisible as possible. Painting a dome after installation is a major task and, if done properly, the seams can be made almost to disappear.

Traditionally, planetarium domes were mounted horizontally, matching the natural horizon of the real night sky. However, because that configuration requires highly inclined chairs for comfortable viewing "straight up," increasingly domes are being built tilted from the horizontal by between 5 and 30 degrees to provide greater comfort. Tilted domes tend to create a favored 'sweet spot' for optimum viewing, centrally about a third of the way up the dome from the lowest point. Tilted domes generally have seating arranged 'stadium-style' in straight, tiered rows; horizontal domes usually have seats in circular rows, arranged in concentric (facing center) or epicentric (facing front) arrays.

Planetariums occasionally include controls such as buttons or joysticks in the arm-rests of seats to allow audience feedback that influences the show in real time.

The edge of the dome (the 'cove') may have lighting to simulate the effect of twilight or urban light pollution, or silhouette models of structures in the area round the planetarium building.

Traditionally, planetariums needed many incandescent lamps around the cove of the dome to help audience entry and exit, to simulate sunrise and sunset, and to provide working light for dome cleaning. More recently, solid-state LED lighting has become available that significantly decreases power consumption and reduces the maintenance requirement, as the lamps no longer have to be changed on a regular basis.

Traditional electromechanical/optical projectors

Traditional planetarium projection apparatus uses a hollow ball with a light inside, and a pinhole for each star, hence the name "star ball." To show some of the brightest stars (such as Sirius, Canopus, Vega), the hole must be so big to let enough light through that there must be a small lens in the hole to focus the light to a sharp point on the dome.

The star ball is usually mounted such that it can rotate as a whole to simulate the Earth's daily rotation, and to change the simulated latitude on Earth. There is also usually a means of rotating to produce the effect of precession of the equinoxes. Often, one such ball is attached at its south ecliptic pole. In that case, the view cannot go so far south that any of the resulting blank area at the south is projected on the dome. Some star projectors have two balls at opposite ends of the projector, like a dumbbell. In that case, all stars can be shown and the view can go to either pole or anywhere between. But care must be taken that the projection fields of the two balls match where they meet or overlap.

Smaller planetarium projectors include a set of fixed stars, Sun, Moon, and planets, and various nebulae. Larger projectors also include comets and a far greater selection of stars. Additional projectors can be added to show twilight around the outside of the screen (complete with city or country scenes) as well as the Milky Way. Others add coordinate lines and constellations, photographic slides, laser displays, and other images.

Each planet is projected by a sharply focused spotlight that makes a spot of light on the dome. Planet projectors must have gearing to move their positioning and thereby simulate the planets' movements. These can be of the following types:

  • Copernican. The axis represents the Sun. The rotating piece that represents each planet carries a light that must be arranged and guided to swivel so it always faces towards the rotating piece that represents the Earth. This presents mechanical problems, including:
The planet lights must be powered by wires, which have to bend about as the planets rotate, and repeatedly bending copper wire tends to cause metal fatigue.
When a planet is at opposition to the Earth, its light is liable to be blocked by the mechanism's central axle.
  • Ptolemaic. Here the central axis represents the Earth. Each planet light is on a mount that rotates only about the central axis, and is aimed by a guide steered by a deferent and an epicycle (or whatever the planetarium maker calls them). Here Ptolemy's number values must be revised to remove the daily rotation, which in a planetarium is catered for otherwise.
  • Computer-controlled. Here all the planet lights are on mounts that rotate only about the central axis and are aimed by a computer.

Despite offering a good viewer experience, traditional star ball projectors have several inherent limitations. From a practical point of view, the low light levels require several minutes for members of the audience to "dark adapt" their eyesight. "Star ball" projection is limited in education terms by its inability to move beyond an earth-bound view of the night sky. Finally, a challenge for most traditional projectors is that the various overlaid projection systems are incapable of proper occultation. This means that a planet image projected on top of a star field (for example) will still show the stars shining through the planet image, degrading the quality of the viewing experience. For related reasons, some planetariums show stars below the horizon projecting on the walls below the dome or on the floor, or (with a bright star or a planet) shining in the eyes of someone in the audience.

However, the new breed of Optical-Mechanical projectors, using fiber-optic technology to display the stars, show a much more realistic view of the sky.

Digital projectors

Zeiss Universarium IX, one of the most sophisticated projectors, circa 2005.

An increasing number of planetariums are using digital technology to replace the entire system of interlinked projectors traditionally employed around a star ball to address some of their limitations. Digital planetarium manufacturers claim reduced maintenance costs and increased reliability for such systems compared with traditional "star balls," noting that they employ few moving parts and do not generally require synchronization of movement across the dome between several separate systems. Some planetariums mix both traditional opto-mechanical projection and digital technologies on the same dome.

In a fully digital planetarium, the dome image is generated by a computer and then projected onto the dome using a variety of technologies, including cathode ray tube, liquid crystal display (LCD), digital light processing (DLP), or laser projectors. Sometimes, a single projector mounted near the center of the dome is employed with a "fish eye lens" to spread the light over the whole dome surface. In other configurations, several projectors around the horizon of the dome are arranged to blend together seamlessly.

Digital projection systems all work by creating the image of the night sky as a large array of pixels. Generally speaking, the more pixels a system can display, the better the viewing experience. Although the first generation of digital projectors were unable to generate enough pixels to match the image quality of the best traditional "star ball" projectors, high-end systems now offer a resolution that approaches the limit of human visual acuity, making their images subjectively indistinguishable from the very best "star balls" to most eyes.

However, these digital star projectors do not show "pinpoint" stars as one would observe in the real sky. Also, the colors of the stars are not always correct. Although digital projectors are good for "traveling" through space, their ability to show a realistic star field is years away. Also, some say that maintenance costs of the digital and video units are significantly higher than those of their optical-mechanical counterparts.

LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetariums. LCOS (liquid crystal on silicon) and modified LCOS projectors have improved on LCD contrast ratios, while also eliminating the “screen door” effect of small gaps between LCD pixels. “Dark chip” DLP projectors improve on the standard DLP design and can offer a relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors. As the technology matures and prices drop, laser projection seems promising for dome projection because it offers bright images, large dynamic range and a very wide color space.

Planetarium show content

Worldwide, most planetariums provide shows to the general public. Traditionally, shows for these audiences with themes such as "What's in the sky tonight?," or shows that pick up on topical issues such as a religious festival (often the Christmas star) linked to the night sky, have been popular. Pre-recorded and live presentation formats are possible. Live formats are preferred by many venues (despite the increased expense) because members of the audience can get immediate answers from an expert presenter.

Since the early 1990s, fully featured 3-D digital planetariums have added an extra degree of freedom to a presenter because they allow simulation of the view from any point in space, not just the earth-bound view that we are most familiar with. This new virtual reality capability to travel through the universe provides important educational benefits: It vividly conveys that space has depth, helping audiences leave behind the ancient misconception that the stars are stuck on the inside of a giant celestial sphere, and to understand the true layout of the Solar System and beyond.

For example, a planetarium can now 'fly' the audience toward one of the familiar constellations such as Orion, revealing that the stars that appear to make up a coordinated shape from our earth-bound viewpoint are at vastly different distances from Earth and so not connected, except in human imagination and mythology. For especially visual or spatially aware people, this experience can be more educationally beneficial than other demonstrations.

Music is an important element to fill out the experience of a good planetarium show, often featuring forms of space-themed music, or music from the genres of space music, space rock, or classical music.

Images of planetariums

  • James S. McDonnell Planetarium in St. Louis, Missouri

  • Planetarium dome, close up Lisbon, Portugal

  • Planetarium in the cruise liner Queen Mary 2.

  • Kuching Planetarium in Sarawak, Malaysia

  • An ancient Egyptian-style planetarium dome in San Jose, California.

  • Alfa Planetarium, Monterrey N.L.Mexico

  • Griffith Obsevatory's central dome contains a planetarium, in Los Angeles, California

Images of planetarium projectors

  • Smallest Zeiss projector ever built

  • Zeiss Model VI, 1968

  • A 1960s era electromechanical projector made by Zeiss of East Germany.

See also

Notes

  1. ↑ Celestial navigation refers to navigation (particularly by sailors) using the positions of the Sun, Moon, planets, or any of 57 "navigational stars" whose coordinates are tabulated in nautical almanacs.
  2. ↑ An orrery is a mechanical device that illustrates the relative positions and motions of planets and moons in the Solar System. It is typically driven by a large clockwork mechanism, with a globe representing the Sun at the center.
  3. ↑ RSA Cosmos Retrieved December 18, 2007.
  4. ↑ MEDIAGLOBE. Konica Minolta. Retrieved December 18, 2007.
  5. ↑ Home Planetarium Trend: Sega Toys Homestar Planetarium Pro CScout Japan. Retrieved December 18, 2007.

References
ISBN links support NWE through referral fees

  • Beck, R. L. 1991. America's Planetariums and Observatories: A Sampling. St. Petersburg, FL: Sunwest Space Systems. ISBN 0963056506.
  • Brenner, Barbara. 1993. Planetarium. A Bank Street Museum Book. New York: Bantam Books. ISBN 0553076191.
  • International Planetarium Society. 2003. The IPS Directory: Including the IPS Directory of the World's Planetariums & the IPS Resource Directory. [United States]: International Planetarium Society. OCLC 54979210.
  • King, Henry C. 1978. Geared to the Stars: The Evolution of Planetariums, Orreries, and Astronomical Clocks. Toronto: University of Toronto Press. ISBN 0802023126.

External links

All links retrieved November 24, 2022.

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