A planetarium (plural planetaria or planetariums) is a theatre 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 planetaria 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, for example 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 simulate an accurate relative motion of the sky. Typical systems can be set to simulate the sky at any point in time, past or present, and often to depict the night sky as it would appear from any point of latitude on Earth.
Planetariums range in size from the 37 meter dome in St. Petersburg, Russia (called “Planetarium No 1”) to three-meter inflatable portable domes where attendees sit on the floor. The largest planetarium in the Western Hemisphere is the Jennifer Chalsty Planetarium at Liberty Science Center in New Jersey (27 meters in diameter). The Birla Planetarium in Kolkata, India is the largest by seating capacity (630 seats).Thereafter, the China Science and Technology Museum Planetarium in Beijing, China has the largest seating capacity (442 seats). In North America, the Hayden Planetarium at the American Museum of Natural History in New York City has the greatest number of seats (423).
The term planetarium is sometimes used generically to describe other devices which illustrate the solar system, such as a computer simulation or an orrery. Planetarium software refers to a software application that renders a three-dimensional image of the sky onto a two-dimensional computer screen. The term planetarian is used to describe a member of the professional staff of a planetarium.
The ancient Greek polymath Archimedes is attributed with creating 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 antiquity, though likely after Archimedes' lifetime. Campanus of Novara (1220–1296) described a planetary equatorium in his Theorica Planetarum, and included instructions on how to build one. The Globe of Gottorf built around 1650 had constellations painted on the inside.These devices would today usually be referred to as orreries (named for the Earl of Orrery, an Irish peer: an 18th-century Earl of Orrery had one built). In fact, many planetaria 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 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 (13 m) 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 living room 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, 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.
While this was being constructed, von Miller was also working at the Zeiss factory with German astronomer Max Wolf, director of the Landessternwarte Heidelberg-Königstuhl observatory of the University of 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 and Rudolf Straubelat 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 (Model I) 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. The first official public showing was at the Deutsches Museum in Munich on October 21, 1923.
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 planetaria for Zeiss, Walther Bauersfeld, also migrated to West Germany with the other members of the Zeiss management team. There he remained on the Zeiss West management team until his death in 1959.
The West German firm resumed making large planetaria in 1954, and the East German firm started making small planetaria 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 planetaria ignore Uranus as being at best marginally visible to the naked eye.
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 planetaria in U.S. high schools.
Armand Spitz recognized that there was a viable market for small inexpensive planetaria. 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.
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 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.
During the 1970s, the OmniMax movie system (now known as IMAX Dome) was conceived to operate on planetarium screens. More recently, some planetaria 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.
Learning Technologies Inc. in Massachusetts offered the first easily portable planetarium in 1977. Philip Sadler designed this patented system 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).
When Germany reunified in 1989, the two Zeiss firms did likewise, and expanded their offerings to cover many different size domes.
In 1983, Evans & Sutherland installed the first digital planetarium projector displaying computer graphics (Hansen planetarium, Salt Lake City, Utah)—the Digistar I projector used a vector graphics system to display starfields as well as line art. This gives the operator great flexibility in showing not only the modern night sky as visible from Earth, but as visible from points far distant in space and time. The newest generations of planetaria, beginning with Digistar 3, offer fulldome video technology. This allows projection of any image the operator wishes.
A new generation of home planetaria was released in Japan by Takayuki Ohira in cooperation with Sega. Ohira is known for building portable planetaria used at exhibitions and events such as the Aichi World Expo in 2005. Later, the Megastar star projectors released by Takayuki Ohira were installed in several science museums around the world. Meanwhile, Sega Toys continues to produce the Homestar series intended for home use; however, projecting 60,000 starson the ceiling makes it semi-professional.
In 2009 Microsoft Research and Go-Dome partnered on the WorldWide Telescope project. The goal of the project is to bring sub-$1000 planetaria to small groups of school children as well as provide technology for large public planetaria.
Planetarium domes range in size from 3 to 35 m in diameter, accommodating from 1 to 500 people. They can be permanent or portable, depending on the application.
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.
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 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.
Planetaria 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.
Often around the edge of the dome (the "cove") are:
Traditionally, planetaria 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 lamps no longer have to be changed on a regular basis.
The world's largest mechanical planetarium is located in Monico, Wisconsin. The Kovac Planetarium. It is 22 feet in diameter and weighs two tons. The globe is made of wood and is driven with a variable speed motor controller. This is the largest mechanical planetarium in the world, larger than the Atwood Globe in Chicago (15 feet in diameter) and one third the size of the Hayden.
Some new planetariums now feature a glass floor, which allows spectators to stand near the center of a sphere surrounded by projected images in all directions, giving the impression of floating in outer space. For example, a small planetarium at AHHAA in Tartu, Estonia features such an installation, with special projectors for images below the feet of the audience, as well as above their heads.
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. In later and modern planetarium star balls, the individual bright stars often have individual projectors, shaped like small hand-held torches, with focusing lenses for individual bright stars. Contact breakers prevent the projectors from projecting below the "horizon".[ citation needed ]
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.
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 these types:-
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 "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, in most traditional projectors 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 planetaria 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.
An increasing number of planetaria 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 synchronisation of movement across the dome between several separate systems. Some planetaria 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 centre of the dome is employed with a fisheye 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.
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.
LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetaria. LCOS 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 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.
Worldwide, most planetaria 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 because a live expert presenter can answer on-the-spot questions raised by the audience.
Since the early 1990s, fully featured 3-D digital planetaria 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 educational 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, 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 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.
An orrery is a mechanical model of the Solar System that illustrates or predicts the relative positions and motions of the planets and moons, usually according to the heliocentric model. It may also represent the relative sizes of these bodies; however, since accurate scaling is often not practical due to the actual large ratio differences, a subdued approximation may be used instead. Though the Greeks had working planetaria, the first orrery that was a planetarium of the modern era was produced in 1704, and one was presented to Charles Boyle, 4th Earl of Orrery – hence the name. They are typically driven by a clockwork mechanism with a globe representing the Sun at the centre, and with a planet at the end of each of the arms.
The Adler Planetarium is a public museum dedicated to the study of astronomy and astrophysics. It was founded in 1930 by Chicago business leader Max Adler. It is located on the northeast tip of Northerly Island at the shore of Lake Michigan in Chicago, Illinois. The Adler was the first planetarium in the United States and is part of Chicago's Museum Campus, which includes the John G. Shedd Aquarium and The Field Museum. The Adler's mission is to inspire exploration and understanding of the universe.
Morehead Planetarium and Science Center is located on the campus of the University of North Carolina at Chapel Hill. It is one of the oldest and largest planetariums in the United States having welcomed more than 7 million visitors by its 60th anniversary in 2009. As a unit of the university, Morehead receives about one-third of its funding through state sources, one-third through ticket and gift sales, and one-third through gifts and grants.
The building known as the London Planetarium is in Marylebone Road, London. It is adjacent to Madame Tussauds and is owned by the same company. A famous London landmark, it was once a notable tourist attraction, housing a planetarium, which offered shows relating to space and astronomy.
The William M. Staerkel Planetarium is a planetarium at Parkland College in Champaign, Illinois. It is the second largest planetarium in the state, the largest being the Adler Planetarium in Chicago, and has the first Carl Zeiss M1015 opto-mechanical star projector installed in the western hemisphere. The Staerkel Planetarium provides science education programs and light show entertainment to as many as 40,000 people each year. It has a 50-foot dome, seats 144, and private group and school show reservations can be made beyond the regular public offerings.
The Fleet Science Center is a science museum and planetarium in Balboa Park, located in San Diego, California. It is at the east end of the El Prado Drive walkway, next to the Bea Evenson Fountain and plaza in central Balboa Park.
Armagh Planetarium is a planetarium located in Armagh, Northern Ireland close to the city centre and neighbouring Armagh Observatory in approximately fourteen acres of landscaped grounds known as the Armagh Astropark.
The McLaughlin Planetarium is a former working planetarium whose building occupies a space immediately to the south of the Royal Ontario Museum in Toronto, at 100 Queen's Park. Founded by a grant from philanthropist Colonel R. Samuel McLaughlin, the facility was opened to the public on October 26, 1968. It had, for its time, a state-of-the-art electro-mechanical Zeiss planetarium projector that was used to project regular themed shows about the stars, planets, and cosmology for visitors. By the 1980s the planetarium's sound-system and domed ceiling were used to display dazzling music-themed laser-light shows. The lower levels of the planetarium contained a gallery called the "Astrocentre" that featured space-related exhibits, related artifacts on the history of astronomy and was also home of the world's first commercial Stellarium
A planetarium projector, also known as a star projector, is a device used to project images of celestial objects onto the dome in a planetarium.
Kyiv Planetarium in Kyiv, Ukraine is one of the largest planetaria in former Soviet states. Opened on January 1, 1952 by the initiative of the scientist-astronomer Serhiy Vsekhsviatskiy (1905–1984), the planetarium has a dome of 23.5 meters in diameter, and seats 320 people.
Digistar is the first computer graphics-based planetarium projection and content system. It was designed by Evans & Sutherland and released in 1983. The technology originally focused on accurate and high quality display of stars, including for the first time showing stars from points of view other than Earth's surface, travelling through the stars, and accurately showing celestial bodies from different times in the past and future. Beginning with the Digistar 3 the system now projects full-dome video.
Chabot Space and Science Center, located in Oakland, California, is a center for science learning featuring interactive exhibits, planetariums, a large screen theater, hands-on activities and three powerful telescopes.
The Rose Center for Earth and Space is a part of the American Museum of Natural History in New York City. The Center's complete name is The Frederick Phineas and Sandra Priest Rose Center for Earth and Space. The main entrance is located on the northern side of the museum on 81st Street near Central Park West in Manhattan's Upper West Side. Completed in 2000, it includes the new Hayden Planetarium, the original of which was opened in 1935 and closed in 1997. Neil deGrasse Tyson is its first and, to date, only director.
Fulldome refers to immersive dome-based video projection environments. The dome, horizontal or tilted, is filled with real-time (interactive) or pre-rendered (linear) computer animations, live capture images, or composited environments.
Centered in the Universe is a fulldome presentation that premiered the evening of October 29, 2006 at the "Galactic Gala" which marked the reopening of the renovated Griffith Observatory in Los Angeles. The 33-minute planetarium program utilizes a Zeiss Universarium star projector and an innovative laser video projection system developed by Evans & Sutherland to create an immersive environment. A live presenter narrates the script.
Armand Neustadter Spitz was an American planetarium designer.
Bryan-Gooding Planetarium in the Alexander Brest Science Theatre is a planetarium in the Museum of Science and History in Jacksonville, Florida, U.S. It was built in 1988 and featured a 60-foot-diameter (18 m) dome-shaped projection screen, JBL stereo sound system, and a Zeiss Jena Optical mechanical planetarium star projector. The facility has seating for 200, and approximately 60,000 people see a planetarium show each year.
WorldWide Telescope (WWT) is an open-source set of applications, data and cloud services, originally created by Microsoft Research but now an open source project hosted on GitHub. The .NET Foundation holds the copyright and the project is managed by the American Astronomical Society and has been supported by grants from the Moore Foundation and National Science Foundation. WWT displays astronomical, earth and planetary data allowing visual navigation through the 3-dimensional (3D) Universe. Users are able to navigate the sky by panning and zooming, or explore the 3D universe from the surface of Earth to past the Cosmic microwave background (CMB), viewing both visual imagery and scientific data about that area and the objects in it. Data is curated from hundreds of different data sources, but its open data nature allows users to explore any third party data that conforms to a WWT supported format. With the rich source of multi-spectral all-sky images it is possible to view the sky in many wavelengths of light. The software utilizes Microsoft's Visual Experience Engine technologies to function. WWT can also be used to visualize arbitrary or abstract data sets and time series data.
B. M. Birla Planetarium is a large planetarium in Chennai providing a virtual tour of the night sky and holding cosmic shows on a specially perforated hemispherical aluminium inner dome. The fifth B. M. Birla planetarium in the country, it is located at Kotturpuram in the Periyar Science and Technology Centre campus which houses eight galleries, namely, Physical Science, Electronics and Communication, Energy, Life Science, Innovation, Transport, International Dolls and Children and Materials Science, with over 500 exhibits. Built in 1988 in the memory of the great industrialist and visionary of India B. M. Birla, it is the most modern planetarium in India. Other Birla planetariums in India include the M. P. Birla Planetarium in Kolkata, the Birla Planetarium in Hyderabad, and the planetariums in Tiruchirapalli and Coimbatore.
Abrams Planetarium is the planetarium on the campus of Michigan State University, Michigan, United States.
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