A planetarium ( pl. : planetariums or planetaria ) is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky , or for training in celestial navigation .
118-407: 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 their motion. The projection can be created in various ways, such as a star ball , slide projector , video , fulldome projector systems, and lasers. Typical systems can be set to simulate
236-400: A " whispering gallery " at its base that at certain places transmits distinct sound to other distant places in the gallery. The half-domes over the apses of Byzantine churches helped to project the chants of the clergy. Although this can complement music, it may make speech less intelligible, leading Francesco Giorgi in 1535 to recommend vaulted ceilings for the choir areas of a church, but
354-425: 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
472-480: A central point. The validity of this is unclear, as domes built underground with corbelled stone layers are in compression from the surrounding earth. The precise definition of "pendentive" has also been a source of academic contention, such as whether or not corbelling is permitted under the definition and whether or not the lower portions of a sail vault should be considered pendentives. Domes with pendentives can be divided into two kinds: simple and compound . In
590-713: A circle . Because they reduce the portion of the dome in tension, these domes are strong but have increased radial thrust. Many of the largest existing domes are of this shape. Masonry saucer domes, because they exist entirely in compression, can be built much thinner than other dome shapes without becoming unstable. The trade-off between the proportionately increased horizontal thrust at their abutments and their decreased weight and quantity of materials may make them more economical, but they are more vulnerable to damage from movement in their supports. Also called gadrooned , fluted , organ-piped , pumpkin , melon , ribbed , parachute , scalloped , or lobed domes, these are
708-554: A circular base alone, circular or polygonal base, circular, elliptical, or polygonal base, or an undefined area. Definitions specifying vertical sections include: semicircular, pointed, or bulbous; semicircular, segmental or pointed; semicircular, segmental, pointed, or bulbous; semicircular, segmental, elliptical, or bulbous; and high profile, hemispherical, or flattened. Sometimes called "false" domes, corbel domes achieve their shape by extending each horizontal layer of stones inward slightly farther than
826-516: A circular base for a drum or compound dome, smoothly continue their curvature to form the dome itself. The dome gives the impression of a square sail pinned down at each corner and billowing upward. These can also be thought of as saucer domes upon pendentives. Sail domes are based upon the shape of a hemisphere and are not to be confused with elliptic parabolic vaults, which appear similar but have different characteristics. In addition to semicircular sail vaults there are variations in geometry such as
944-429: A dome. The top of a dome is the "crown". The inner side of a dome is called the "intrados" and the outer side is called the "extrados". As with arches, the "springing" of a dome is the base level from which the dome rises and the "haunch" is the part that lies roughly halfway between the base and the top. Domes can be supported by an elliptical or circular wall called a "drum". If this structure extends to ground level,
1062-531: 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
1180-406: 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
1298-546: A flat ceiling filled with as many coffers as possible for where preaching would occur. Cavities in the form of jars built into the inner surface of a dome may serve to compensate for this interference by diffusing sound in all directions, eliminating echoes while creating a "divine effect in the atmosphere of worship." This technique was written about by Vitruvius in his Ten Books on Architecture , which describes bronze and earthenware resonators. The material, shape, contents, and placement of these cavity resonators determine
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#17327721017571416-402: A hemispherical dome can be 2.5 times thinner than a semicircular arch, and a dome with the profile of an equilateral arch can be thinner still. The optimal shape for a masonry dome of equal thickness provides for perfect compression, with none of the tension or bending forces against which masonry is weak. For a particular material, the optimal dome geometry is called the funicular surface ,
1534-523: 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
1652-516: A limited number of simple elements and joints and efficiently resolve a dome's internal forces. Their efficiency is said to increase with size. Although not first invented by Buckminster Fuller , they are associated with him because he designed many geodesic domes and patented them in the United States. The hemispherical dome is a surface formed by the rotation around a vertical axis of a semicircle . Like other "rotational domes" formed by
1770-805: A lot of attention. Next Zeiss planetariums were opened in Rome (1928, in Aula Ottagona , part of the Baths of Diocletian ), Chicago (1930), Osaka (1937, in the Osaka City Electricity Science Museum ). 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
1888-517: A low rise to span ratio or covering a rectangular plan. Sail vaults of all types have a variety of thrust conditions along their borders, which can cause problems, but have been widely used from at least the sixteenth century. The second floor of the Llotja de la Seda is covered by a series of nine meter wide sail vaults. Also called segmental domes (a term sometimes also used for cloister vaults), or calottes , these have profiles of less than half
2006-476: 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
2124-521: A pointed and bulbous tradition inherited by some early Islamic mosques. Modern academic study of the topic has been controversial and confused by inconsistent definitions, such as those for cloister vaults and domical vaults. Dictionary definitions of the term "dome" are often general and imprecise. Generally-speaking, it "is non-specific, a blanket-word to describe an hemispherical or similar spanning element." Published definitions include: hemispherical roofs alone; revolved arches ; and vaults on
2242-553: A powerful mortar. The aggregate transitioned over the centuries to pieces of fired clay, then to Roman bricks. By the sixth century, bricks with large amounts of mortar were the principle vaulting materials. Pozzolana appears to have only been used in central Italy. Brick domes were the favored choice for large-space monumental coverings until the Industrial Age , due to their convenience and dependability. Ties and chains of iron or wood could be used to resist stresses. In
2360-408: 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
2478-527: 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. Zeiss Planetarium became popular, and attracted
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#17327721017572596-511: 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
2714-450: A single arch or a set of multiple projecting nested arches placed diagonally over an internal corner. Squinch forms also include trumpet arches, niche heads (or half-domes), trumpet arches with "anteposed" arches, and muqarnas arches. Squinches transfer the weight of a dome across the gaps created by the corners and into the walls. Pendentives are triangular sections of a sphere, like concave spandrels between arches, and transition from
2832-564: A single point of origin. Their appearance in northern Russian architecture predates the Tatar occupation of Russia and so is not easily explained as the result of that influence. They became popular in the second half of the 15th century in the Low Countries of Northern Europe, possibly inspired by the finials of minarets in Egypt and Syria, and developed in the 16th and 17th centuries in
2950-588: A smaller diameter dome immediately above them, as in the Hagia Sophia, or a drum and dome, as in many Renaissance and post-Renaissance domes, with both forms resulting in greater height. One of the earliest types of ribbed vault, the first known examples are found in the Great Mosque of Córdoba in the 10th century. Rather than meeting in the center of the dome, the ribs characteristically intersect one another off-center, forming an empty polygonal space in
3068-448: 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 planetariums mix both traditional opto-mechanical projection and digital technologies on
3186-567: A system of squinches or pendentives used to accommodate the transition in shape from a rectangular or square space to the round or polygonal base of the dome. The dome's apex may be closed or may be open in the form of an oculus , which may itself be covered with a roof lantern and cupola. Domes have a long architectural lineage that extends back into prehistory . Domes were built in ancient Mesopotamia , and they have been found in Persian , Hellenistic , Roman , and Chinese architecture in
3304-497: A three-dimensional image of the sky onto a two-dimensional computer screen, or in a virtual reality headset for a 3D representation. 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
3422-543: A type of dome divided at the base into curved segments, which follow the curve of the elevation . "Fluted" may refer specifically to this pattern as an external feature, such as was common in Mamluk Egypt . The "ribs" of a dome are the radial lines of masonry that extend from the crown down to the springing. The central dome of the Hagia Sophia uses the ribbed method, which accommodates a ring of windows between
3540-542: A vertical axis of a semi-ellipse . Like other "rotational domes" formed by the rotation of a curve around a vertical axis, ellipsoidal domes have circular bases and horizontal sections and are a type of "circular dome" for that reason. Geodesic domes are the upper portion of geodesic spheres. They are composed of a framework of triangles in a polyhedron pattern. The structures are named for geodesics and are based upon geometric shapes such as icosahedrons , octahedrons or tetrahedrons . Such domes can be created using
3658-399: Is an architectural element similar to the hollow upper half of a sphere . There is significant overlap with the term cupola , which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a matter of controversy and there are a wide variety of forms and specialized terms to describe them. A dome can rest directly upon a rotunda wall, a drum , or
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3776-776: Is called a Melon dome. A paraboloid dome is a surface formed by the rotation around a vertical axis of a sector of a parabola. Like other "rotational domes" formed by the rotation of a curve around a vertical axis, paraboloid domes have circular bases and horizontal sections and are a type of "circular dome" for that reason. Because of their shape, paraboloid domes experience only compression, both radially and horizontally. Also called sail vaults , handkerchief vaults , domical vaults (a term sometimes also applied to cloister vaults), pendentive domes (a term that has also been applied to compound domes), Bohemian vaults , or Byzantine domes , this type can be thought of as pendentives that, rather than merely touching each other to form
3894-401: Is made a complete and self-supporting ring. The upper portion of a masonry dome is always in compression and is supported laterally, so it does not collapse except as a whole unit and a range of deviations from the ideal in this shallow upper cap are equally stable. Because voussoir domes have lateral support, they can be made much thinner than corresponding arches of the same span. For example,
4012-481: Is not well documented. That the dome was known to early Mesopotamia may explain the existence of domes in both China and the West in the first millennium BC. Another explanation, however, is that the use of the dome shape in construction did not have a single point of origin and was common in virtually all cultures long before domes were constructed with enduring materials. Corbelled stone domes have been found from
4130-546: Is the igloo , a shelter built from blocks of compact snow and used by the Inuit , among others. The Himba people of Namibia construct "desert igloos" of wattle and daub for use as temporary shelters at seasonal cattle camps, and as permanent homes by the poor. Extraordinarily thin domes of sun-baked clay 20 feet in diameter, 30 feet high, and nearly parabolic in curve, are known from Cameroon . The historical development from structures like these to more sophisticated domes
4248-517: Is the first to have squinches create a regular octagon as a base for the dome, which then became the standard practice. Cylindrical or polygonal plan tower tombs with conical roofs over domes also exist beginning in the 11th century. The Seljuk Empire 's notables built tomb-towers, called "Turkish Triangles", as well as cube mausoleums covered with a variety of dome forms. Seljuk domes included conical, semi-circular, and pointed shapes in one or two shells. Shallow semi-circular domes are mainly found from
4366-689: Is the largest by seating capacity, having 630 seats. In North America, the Hayden Planetarium at the American Museum of Natural History in New York City has the greatest number of seats, at 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
4484-597: 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. A great boost to
4602-522: The Earl of Orrery ). In fact, many planetariums today have projection orreries, which project onto the dome the Solar System (including the Sun and planets up to Saturn ) in their regular orbital paths. In 1229, following the conclusion of the Fifth Crusade , Holy Roman Emperor Frederick II of Hohenstaufen brought back a tent with scattered holes representing stars or planets . The device
4720-660: 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 Straubel 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
4838-490: The Middle East and Central Asia , domes and drums constructed from mud brick and baked brick were sometimes covered with brittle ceramic tiles on the exterior to protect against rain and snow. The new building materials of the 19th century and a better understanding of the forces within structures from the 20th century opened up new possibilities. Iron and steel beams, steel cables, and pre-stressed concrete eliminated
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4956-647: The Neolithic period in the ancient Near East , and in the Middle East to Western Europe from antiquity. The kings of Achaemenid Persia held audiences and festivals in domical tents derived from the nomadic traditions of central Asia. Simple domical mausoleums existed in the Hellenistic period. The remains of a large domed circular hall in the Parthian capital city of Nyssa has been dated to perhaps
5074-522: The Safavid dynasty (1501–1732) are characterized by a distinctive bulbous profile and are considered the last generation of Persian domes. They are generally thinner than earlier domes and are decorated with a variety of colored glazed tiles and complex vegetal patterns, and they were influential on those of other Islamic styles, such as the Mughal architecture of India. An exaggerated style of onion dome on
5192-418: The University of Kassel in 1983. A masonry dome produces thrusts downward and outward. They are thought of in terms of two kinds of forces at right angles from one another: meridional forces (like the meridians , or lines of longitude, on a globe) are compressive only, and increase towards the base, while hoop forces (like the lines of latitude on a globe) are in compression at the top and tension at
5310-565: The ancient world , as well as among a number of indigenous building traditions throughout the world. Dome structures were common in both Byzantine architecture and Sasanian architecture , which influenced that of the rest of Europe and Islam , respectively, in the Middle Ages . The domes of European Renaissance architecture spread from Italy in the early modern period , while domes were frequently employed in Ottoman architecture at
5428-515: 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. Learning Technologies Inc. in Massachusetts offered
5546-404: The 20th century have allowed for large dome-shaped structures that deviate from the traditional compressive structural behavior of masonry domes. Popular usage of the term has expanded to mean "almost any long-span roofing system". The word " cupola " is another word for "dome", and is usually used for a small dome upon a roof or turret . "Cupola" has also been used to describe the inner side of
5664-608: The Italian word duomo , the German/Icelandic/Danish word dom ("cathedral"), and the English word dome as late as 1656, when it meant a "Town-House, Guild-Hall, State-House, and Meeting-House in a city." The French word dosme came to acquire the meaning of a cupola vault, specifically, by 1660. This French definition gradually became the standard usage of the English dome in the eighteenth century as many of
5782-649: The Netherlands before spreading to Germany, becoming a popular element of the baroque architecture of Central Europe. German bulbous domes were also influenced by Russian and Eastern European domes. The examples found in various European architectural styles are typically wooden. Examples include Kazan Church in Kolomenskoye and the Brighton Pavilion by John Nash . In Islamic architecture, they are typically made of masonry, rather than timber, with
5900-587: The Seljuk era. The double-shell domes were either discontinuous or continuous. The domed enclosure of the Jameh Mosque of Isfahan , built in 1086-7 by Nizam al-Mulk , was the largest masonry dome in the Islamic world at that time, had eight ribs, and introduced a new form of corner squinch with two quarter domes supporting a short barrel vault. In 1088 Tāj-al-Molk, a rival of Nizam al-Mulk, built another dome at
6018-474: 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, 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
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#17327721017576136-424: The base, with the transition in a hemispherical dome occurring at an angle of 51.8 degrees from the top. The thrusts generated by a dome are directly proportional to the weight of its materials. Grounded hemispherical domes generate significant horizontal thrusts at their haunches. The outward thrusts in the lower portion of a hemispherical masonry dome can be counteracted with the use of chains incorporated around
6254-570: The case of the simple dome , the pendentives are part of the same sphere as the dome itself; however, such domes are rare. In the case of the more common compound dome , the pendentives are part of the surface of a larger sphere below that of the dome itself and form a circular base for either the dome or a drum section. The fields of engineering and architecture have lacked common language for domes, with engineering focused on structural behavior and architecture focused on form and symbolism. Additionally, new materials and structural systems in
6372-467: The center. Geometry is a key element of the designs, with the octagon being perhaps the most popular shape used. Whether the arches are structural or purely decorative remains a matter of debate. The type may have an eastern origin, although the issue is also unsettled. Examples are found in Spain, North Africa, Armenia, Iran, France, and Italy. The ellipsoidal dome is a surface formed by the rotation around
6490-519: The church of Santo Tomás de las Ollas in Spain has an oval dome over its oval plan. Other examples of medieval oval domes can be found covering rectangular bays in churches. Oval plan churches became a type in the Renaissance and popular in the Baroque style. The dome built for the basilica of Vicoforte by Francesco Gallo was one of the largest and most complex ever made. Although the ellipse
6608-505: The circle being considered the most perfect of forms. According to E. Baldwin Smith, from the late Stone Age the dome-shaped tomb was used as a reproduction of the ancestral, god-given shelter made permanent as a venerated home of the dead. The instinctive desire to do this resulted in widespread domical mortuary traditions across the ancient world, from the stupas of India to the tholos tombs of Iberia . By Hellenistic and Roman times,
6726-459: The circumference or with external buttressing, although cracking along the meridians is natural. For small or tall domes with less horizontal thrust, the thickness of the supporting arches or walls can be enough to resist deformation, which is why drums tend to be much thicker than the domes they support. Unlike voussoir arches, which require support for each element until the keystone is in place, domes are stable during construction as each level
6844-456: The comparable shape in three dimensions to a catenary curve for a two-dimensional arch. Adding a weight to the top of a pointed dome, such as the heavy cupola at the top of Florence Cathedral , changes the optimal shape to more closely match the actual pointed shape of the dome. The pointed profiles of many Gothic domes more closely approximate the optimal dome shape than do hemispheres, which were favored by Roman and Byzantine architects due to
6962-400: The corners of a square bay to the circular base of a dome. The curvature of the pendentives is that of a sphere with a diameter equal to the diagonal of the square bay. Pendentives concentrate the weight of a dome into the corners of the bay. The earliest domes in the Middle East were built with mud-brick and, eventually, with baked brick and stone. Domes of wood allowed for wide spans due to
7080-417: 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,
7198-443: The dome's surface of revolution, or be straight lengths with the connecting points or nodes lying upon the surface of revolution. Single-layer structures are called frame or skeleton types and double-layer structures are truss types, which are used for large spans. When the covering also forms part of the structural system, it is called a stressed skin type. The formed surface type consists of sheets joined at bent edges to form
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#17327721017577316-452: 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 ,
7434-553: The domical tholos had become the customary cemetery symbol. Domes and tent-canopies were also associated with the heavens in Ancient Persia and the Hellenistic-Roman world. A dome over a square base reflected the geometric symbolism of those shapes. The circle represented perfection, eternity, and the heavens. The square represented the earth. An octagon was intermediate between the two. The distinct symbolism of
7552-483: The effect they have: reinforcing certain frequencies or absorbing them. Also called a corbelled dome , cribbed dome , or false dome , these are different from a 'true dome' in that they consist of purely horizontal layers. As the layers get higher, each is slightly cantilevered , or corbeled , toward the center until meeting at the top. A monumental example is the Mycenaean Treasury of Atreus from
7670-576: 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 planetarium projectors, beginning with Digistar 3 , offer fulldome video technology. This allows for
7788-472: The first century AD, showing "...the existence of a monumental domical tradition in Central Asia that had hitherto been unknown and which seems to have preceded Roman Imperial monuments or at least to have grown independently from them." It likely had a wooden dome. Persian architecture likely inherited an architectural tradition of dome-building dating back to the earliest Mesopotamian domes. Due to
7906-952: The first century BC, such as the Tabularium of Rome from 78 BC. Others include the Baths of Antoninus in Carthage (145–160) and the Palatine Chapel at Aachen (13th – 14th century). The most famous example is the Renaissance octagonal dome of Filippo Brunelleschi over the Florence Cathedral. Thomas Jefferson , the third president of the United States, installed an octagonal dome above the West front of his plantation house, Monticello . Also called domes on pendentives or pendentive domes (a term also applied to sail vaults), compound domes have pendentives that support
8024-477: 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
8142-632: The first examples in Asia Minor date to around 4000 B.C. The geometry was eventually defined using combinations of circular arcs, transitioning at points of tangency. If the Romans created oval domes, it was only in exceptional circumstances. The Roman foundations of the oval plan Church of St. Gereon in Cologne point to a possible example. Domes in the Middle Ages also tended to be circular, though
8260-610: The first planetariums 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 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
8378-574: The forefront of Persian architecture as a result. Pre-Islamic domes in Persia are commonly semi-elliptical, with pointed domes and those with conical outer shells being the majority of the domes in the Islamic periods. The area of north-eastern Iran was, along with Egypt, one of two areas notable for early developments in Islamic domed mausoleums, which appear in the tenth century. The Samanid Mausoleum in Transoxiana dates to no later than 943 and
8496-655: 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
8614-451: The heavenly or cosmic tent stemming from the royal audience tents of Achaemenid and Indian rulers was adopted by Roman rulers in imitation of Alexander the Great , becoming the imperial baldachin . This probably began with Nero , whose " Golden House " also made the dome a feature of palace architecture. The dual sepulchral and heavenly symbolism was adopted by early Christians in both
8732-455: 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
8850-482: The late Bronze Age . A single or double layer space frame in the form of a dome, a braced dome is a generic term that includes ribbed , Schwedler , three-way grid , lamella or Kiewitt , lattice , and geodesic domes . The different terms reflect different arrangements in the surface members. Braced domes often have a very low weight and are usually used to cover spans of up to 150 meters. Often prefabricated, their component members can either lie on
8968-411: The lower one until they meet at the top. A "false" dome may also refer to a wooden dome. The Italian use of the term finto , meaning "false", can be traced back to the 17th century in the use of vaulting made of reed mats and gypsum mortar. "True" domes are said to be those whose structure is in a state of compression, with constituent elements of wedge-shaped voussoirs , the joints of which align with
9086-618: 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
9204-403: The modern world can be found over religious buildings, legislative chambers, sports stadiums, and a variety of functional structures. The English word "dome" ultimately derives from the ancient Greek and Latin domus ("house"), which, up through the Renaissance, labeled a revered house, such as a Domus Dei , or "House of God", regardless of the shape of its roof. This is reflected in the uses of
9322-660: The most impressive Houses of God were built with monumental domes, and in response to the scientific need for more technical terms. Across the ancient world, curved-roof structures that would today be called domes had a number of different names reflecting a variety of shapes, traditions, and symbolic associations. The shapes were derived from traditions of pre-historic shelters made from various impermanent pliable materials and were only later reproduced as vaulting in more durable materials. The hemispherical shape often associated with domes today derives from Greek geometry and Roman standardization, but other shapes persisted, including
9440-449: The need for external buttressing and enabled much thinner domes. Whereas earlier masonry domes may have had a radius to thickness ratio of 50, the ratio for modern domes can be in excess of 800. The lighter weight of these domes not only permitted far greater spans, but also allowed for the creation of large movable domes over modern sports stadiums. Experimental rammed earth domes were made as part of work on sustainable architecture at
9558-402: 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 planetariums show stars below the horizon projecting on
9676-691: The opposite end of the same mosque with interlacing ribs forming five-pointed stars and pentagons. This is considered the landmark Seljuk dome, and may have inspired subsequent patterning and the domes of the Il-Khanate period. The use of tile and of plain or painted plaster to decorate dome interiors, rather than brick, increased under the Seljuks. Beginning in the Ilkhanate , Persian domes achieved their final configuration of structural supports, zone of transition, drum, and shells, and subsequent evolution
9794-581: The place of a prince during royal ceremonies. Over time such domes became primarily focal points for decoration or the direction of prayer. The use of domes in mausoleums can likewise reflect royal patronage or be seen as representing the honor and prestige that domes symbolized, rather than having any specific funerary meaning. The wide variety of dome forms in medieval Islam reflected dynastic, religious, and social differences as much as practical building considerations. Because domes are concave from below, they can reflect sound and create echoes. A dome may have
9912-402: 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
10030-509: The planets. The discovery of the Antikythera mechanism proved that such devices already existed during antiquity , though likely after Archimedes' lifetime. Campanus of Novara 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
10148-515: 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. Armand Spitz recognized that there was a viable market for small inexpensive planetaria. His first model, the Spitz A,
10266-422: The projection of any image. 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
10384-472: The projectors from projecting below the "horizon". 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
10502-458: The relatively light and flexible nature of the material and were the normal method for domed churches by the 7th century, although most domes were built with the other less flexible materials. Wooden domes were protected from the weather by roofing, such as copper or lead sheeting. Domes of cut stone were more expensive and never as large, and timber was used for large spans where brick was unavailable. Roman concrete used an aggregate of stone with
10620-499: 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
10738-417: The ribs at the base of the dome. The central dome of St. Peter's Basilica also uses this method. Cultures from pre-history to modern times constructed domed dwellings using local materials. Although it is not known when the first dome was created, sporadic examples of early domed structures have been discovered. The earliest discovered may be four small dwellings made of Mammoth tusks and bones. The first
10856-471: The rotation of a curve around a vertical axis, hemispherical domes have circular bases and horizontal sections and are a type of "circular dome" for that reason. They experience vertical compression along their meridians, but horizontally experience compression only in the portion above 51.8 degrees from the top. Below this point, hemispherical domes experience tension horizontally, and usually require buttressing to counteract it. According to E. Baldwin Smith, it
10974-402: The round building may be called a " rotunda ". Drums are also called " tholobates " and may or may not contain windows. A " tambour " or " lantern " is the equivalent structure over a dome's oculus, supporting a cupola. When the base of the dome does not match the plan of the supporting walls beneath it (for example, a dome's circular base over a square bay ), techniques are employed to bridge
11092-428: 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
11210-456: The same time. Baroque and Neoclassical architecture took inspiration from Roman domes. Advancements in mathematics, materials, and production techniques resulted in new dome types. Domes have been constructed over the centuries from mud, snow, stone, wood, brick, concrete, metal, glass, and plastic. The symbolism associated with domes includes mortuary , celestial , and governmental traditions that have likewise altered over time. The domes of
11328-495: The scarcity of wood in many areas of the Iranian plateau and Greater Iran , domes were an important part of vernacular architecture throughout Persian history. The Persian invention of the squinch , a series of concentric arches forming a half-cone over the corner of a room, enabled the transition from the walls of a square chamber to an octagonal base for a dome in a way reliable enough for large constructions and domes moved to
11446-409: 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
11564-593: 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 use
11682-843: 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. Planetaria 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 , its dome measuring 27 meters in diameter. The Birla Planetarium in Kolkata, India
11800-460: 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. Live format is preferred by many venues as a live speaker or presenter can answer questions raised by the audience. Since the early 1990s, fully featured 3-D digital planetariums have added an extra degree of freedom to a presenter giving
11918-476: 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 planetariums provide shows to the general public. Traditionally, shows for these audiences with themes such as "What's in
12036-465: The structure. Also called domical vaults (a term sometimes also applied to sail vaults), polygonal domes , coved domes , gored domes , segmental domes (a term sometimes also used for saucer domes), paneled vaults , or pavilion vaults , these are domes that maintain a polygonal shape in their horizontal cross section. The component curved surfaces of these vaults are called severies , webs , or cells . The earliest known examples date to
12154-457: The thick and heavy bulging portion serving to buttress against the tendency of masonry domes to spread at their bases. The Taj Mahal is a famous example. An oval dome is a dome of oval shape in plan, profile, or both. The term comes from the Latin ovum , meaning "egg". The earliest oval domes were used by convenience in corbelled stone huts as rounded but geometrically undefined coverings, and
12272-564: 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 an 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. Dome A dome (from Latin domus )
12390-556: The two shells of the dome have significantly different profiles, which spread rapidly throughout the region. The development of taller drums also continued into the Timurid period. The large, bulbous, fluted domes on tall drums that are characteristic of 15th century Timurid architecture were the culmination of the Central Asian and Iranian tradition of tall domes with glazed tile coverings in blue and other colors. The domes of
12508-505: The two. One technique is to use corbelling, progressively projecting horizontal layers from the top of the supporting wall to the base of the dome, such as the corbelled triangles often used in Seljuk and Ottoman architecture. The simplest technique is to use diagonal lintels across the corners of the walls to create an octagonal base. Another is to use arches to span the corners, which can support more weight. A variety of these techniques use what are called " squinches ". A squinch can be
12626-482: The use of domes in architecture and in the ciborium , a domical canopy like the baldachin used as a ritual covering for relics or the church altar . The celestial symbolism of the dome, however, was the preeminent one by the Christian era . In the early centuries of Islam, domes were closely associated with royalty. A dome built in front of the mihrab of a mosque, for example, was at least initially meant to emphasize
12744-432: 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 planetariums are using digital technology to replace the entire system of interlinked projectors traditionally employed around
12862-525: Was a shape likely known to the Assyrians, defined by Greek theoretical mathematicians, and standardized by Roman builders. Bulbous domes bulge out beyond their base diameters, offering a profile greater than a hemisphere. An onion dome is a greater than hemispherical dome with a pointed top in an ogee profile. They are found in the Near East , Middle East , Persia, and India and may not have had
12980-634: 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
13098-467: 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
13216-407: 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
13334-584: Was found by a farmer in Mezhirich , Ukraine, in 1965 while he was digging in his cellar and archaeologists unearthed three more. They date from 19,280 – 11,700 BC. In modern times , the creation of relatively simple dome-like structures has been documented among various indigenous peoples around the world. The wigwam was made by Native Americans using arched branches or poles covered with grass or hides. The Efé people of central Africa construct similar structures , using leaves as shingles. Another example
13452-536: 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
13570-522: Was known, in practice, domes of this shape were created by combining segments of circles. Popular in the 16th and 17th centuries, oval and elliptical plan domes can vary their dimensions in three axes or two axes. A sub-type with the long axis having a semicircular section is called a Murcia dome, as in the Chapel of the Junterones at Murcia Cathedral . When the short axis has a semicircular section, it
13688-486: 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 Frisian city of 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
13806-402: Was operated internally with a spinnable table that rotated the tent. The small size of typical 18th century orreries limited their impact, and towards the end of that century a number of educators attempted to create a larger sized version. The efforts of Adam Walker (1730–1821) and his sons are noteworthy in their attempts to fuse theatrical illusions with education. Walker's Eidouranion was
13924-405: Was restricted to variations in form and shell geometry. Characteristic of these domes are the use of high drums and several types of discontinuous double-shells, and the development of triple-shells and internal stiffeners occurred at this time. The construction of tomb towers decreased. The 7.5 meter wide double dome of Soltan Bakht Agha Mausoleum (1351–1352) is the earliest known example in which
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