Planetarium (formerly Tycho Brahe Planetarium ) is located at the southern end of the lake Skt. Jørgens Sø in Copenhagen , Denmark . It was designed by MAA Knud Munk (1936–2016) and opened on November 1, 1989.
123-462: The planetarium is built where the Saltlageret theater was previously located. The foundation stone was placed on February 22, 1988, and the planetarium opened on November 1, 1989. The financial basis for building the planetarium was a 50,000,000 DKK donation by the foundation Bodil Pedersen Fonden to the foundation Uraniafonden, which administered the construction of the planetarium. Since 1989,
246-425: 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
369-476: A central subject for astronomical research since antiquity . The Sun orbits the Galactic Center at a distance of 24,000 to 28,000 light-years . From Earth, it is 1 astronomical unit ( 1.496 × 10 km ) or about 8 light-minutes away. Its diameter is about 1,391,400 km ( 864,600 mi ), 109 times that of Earth. Its mass is about 330,000 times that of Earth, making up about 99.86% of
492-561: A distance of one astronomical unit (AU) from the Sun (that is, at or near Earth's orbit). Sunlight on the surface of Earth is attenuated by Earth's atmosphere , so that less power arrives at the surface (closer to 1,000 W/m ) in clear conditions when the Sun is near the zenith . Sunlight at the top of Earth's atmosphere is composed (by total energy) of about 50% infrared light, 40% visible light, and 10% ultraviolet light. The atmosphere filters out over 70% of solar ultraviolet, especially at
615-403: A fairly small amount of power being generated per cubic metre . Theoretical models of the Sun's interior indicate a maximum power density, or energy production, of approximately 276.5 watts per cubic metre at the center of the core, which, according to Karl Kruszelnicki , is about the same power density inside a compost pile . The fusion rate in the core is in a self-correcting equilibrium:
738-526: 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
861-406: 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
984-414: A few millimeters. Re-emission happens in a random direction and usually at slightly lower energy. With this sequence of emissions and absorptions, it takes a long time for radiation to reach the Sun's surface. Estimates of the photon travel time range between 10,000 and 170,000 years. In contrast, it takes only 2.3 seconds for neutrinos , which account for about 2% of the total energy production of
1107-478: A few shows in English every day. There are also two smaller exhibitions. One about the moon and the other about Saturn's rings. 55°40′28″N 12°33′29″E / 55.67444°N 12.55806°E / 55.67444; 12.55806 Planetarium A planetarium ( pl. : planetariums or planetaria ) is a theatre built primarily for presenting educational and entertaining shows about astronomy and
1230-401: A granular appearance called the solar granulation at the smallest scale and supergranulation at larger scales. Turbulent convection in this outer part of the solar interior sustains "small-scale" dynamo action over the near-surface volume of the Sun. The Sun's thermal columns are Bénard cells and take the shape of roughly hexagonal prisms. The visible surface of the Sun, the photosphere,
1353-523: 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
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#17330857665411476-766: 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
1599-472: 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
1722-508: A period known as the Maunder minimum . This coincided in time with the era of the Little Ice Age , when Europe experienced unusually cold temperatures. Earlier extended minima have been discovered through analysis of tree rings and appear to have coincided with lower-than-average global temperatures. The temperature of the photosphere is approximately 6,000 K, whereas the temperature of
1845-485: A phenomenon described by Hale's law . During the solar cycle's declining phase, energy shifts from the internal toroidal magnetic field to the external poloidal field, and sunspots diminish in number and size. At solar-cycle minimum, the toroidal field is, correspondingly, at minimum strength, sunspots are relatively rare, and the poloidal field is at its maximum strength. With the rise of the next 11-year sunspot cycle, differential rotation shifts magnetic energy back from
1968-408: 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
2091-473: A result, the outward-flowing solar wind stretches the interplanetary magnetic field outward, forcing it into a roughly radial structure. For a simple dipolar solar magnetic field, with opposite hemispherical polarities on either side of the solar magnetic equator, a thin current sheet is formed in the solar wind. At great distances, the rotation of the Sun twists the dipolar magnetic field and corresponding current sheet into an Archimedean spiral structure called
2214-517: 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
2337-505: 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
2460-410: A slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers, reducing the density and hence the fusion rate and correcting the perturbation ; and a slightly lower rate would cause the core to cool and shrink slightly, increasing the density and increasing the fusion rate and again reverting it to its present rate. The radiative zone
2583-407: A software application that renders 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
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#17330857665412706-448: 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
2829-406: A transition layer, the tachocline . This is a region where the sharp regime change between the uniform rotation of the radiative zone and the differential rotation of the convection zone results in a large shear between the two—a condition where successive horizontal layers slide past one another. Presently, it is hypothesized that a magnetic dynamo, or solar dynamo , within this layer generates
2952-639: Is by far the brightest object in the Earth's sky , with an apparent magnitude of −26.74. This is about 13 billion times brighter than the next brightest star, Sirius , which has an apparent magnitude of −1.46. One astronomical unit (about 150 million kilometres; 93 million miles) is defined as the mean distance between the centres of the Sun and the Earth. The instantaneous distance varies by about ± 2.5 million km or 1.55 million miles as Earth moves from perihelion on ~ January 3rd to aphelion on ~ July 4th. At its average distance, light travels from
3075-436: Is defined to begin at the distance where the flow of the solar wind becomes superalfvénic —that is, where the flow becomes faster than the speed of Alfvén waves, at approximately 20 solar radii ( 0.1 AU ). Turbulence and dynamic forces in the heliosphere cannot affect the shape of the solar corona within, because the information can only travel at the speed of Alfvén waves. The solar wind travels outward continuously through
3198-402: Is facilitated by the full ionization of helium in the transition region, which significantly reduces radiative cooling of the plasma. The transition region does not occur at a well-defined altitude, but forms a kind of nimbus around chromospheric features such as spicules and filaments , and is in constant, chaotic motion. The transition region is not easily visible from Earth's surface, but
3321-409: Is only 84% of what it was in the protostellar phase (before nuclear fusion in the core started). In the future, helium will continue to accumulate in the core, and in about 5 billion years this gradual build-up will eventually cause the Sun to exit the main sequence and become a red giant . The chemical composition of the photosphere is normally considered representative of the composition of
3444-441: Is readily observable from space by instruments sensitive to extreme ultraviolet . The corona is the next layer of the Sun. The low corona, near the surface of the Sun, has a particle density around 10 m to 10 m . The average temperature of the corona and solar wind is about 1,000,000–2,000,000 K; however, in the hottest regions it is 8,000,000–20,000,000 K. Although no complete theory yet exists to account for
3567-410: Is strongly attenuated by Earth's ozone layer , so that the amount of UV varies greatly with latitude and has been partially responsible for many biological adaptations, including variations in human skin color . High-energy gamma ray photons initially released with fusion reactions in the core are almost immediately absorbed by the solar plasma of the radiative zone, usually after traveling only
3690-477: Is suggested by a high abundance of heavy elements in the Solar System, such as gold and uranium , relative to the abundances of these elements in so-called Population II , heavy-element-poor, stars. The heavy elements could most plausibly have been produced by endothermic nuclear reactions during a supernova, or by transmutation through neutron absorption within a massive second-generation star. The Sun
3813-470: Is tens to hundreds of kilometers thick, and is slightly less opaque than air on Earth. Because the upper part of the photosphere is cooler than the lower part, an image of the Sun appears brighter in the center than on the edge or limb of the solar disk, in a phenomenon known as limb darkening . The spectrum of sunlight has approximately the spectrum of a black-body radiating at 5,772 K (9,930 °F), interspersed with atomic absorption lines from
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3936-503: Is the star at the center of the Solar System . It is a massive, nearly perfect sphere of hot plasma , heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is by far the most important source of energy for life on Earth . The Sun has been an object of veneration in many cultures. It has been
4059-572: 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
4182-437: Is the layer below which the Sun becomes opaque to visible light. Photons produced in this layer escape the Sun through the transparent solar atmosphere above it and become solar radiation, sunlight. The change in opacity is due to the decreasing amount of H ions , which absorb visible light easily. Conversely, the visible light perceived is produced as electrons react with hydrogen atoms to produce H ions. The photosphere
4305-424: Is the most prominent variation in which the number and size of sunspots waxes and wanes. The solar magnetic field extends well beyond the Sun itself. The electrically conducting solar wind plasma carries the Sun's magnetic field into space, forming what is called the interplanetary magnetic field . In an approximation known as ideal magnetohydrodynamics , plasma particles only move along magnetic field lines. As
4428-531: Is the only region of the Sun that produces an appreciable amount of thermal energy through fusion; 99% of the Sun's power is generated in the innermost 24% of its radius, and almost no fusion occurs beyond 30% of the radius. The rest of the Sun is heated by this energy as it is transferred outward through many successive layers, finally to the solar photosphere where it escapes into space through radiation (photons) or advection (massive particles). The proton–proton chain occurs around 9.2 × 10 times each second in
4551-420: Is the thickest layer of the Sun, at 0.45 solar radii. From the core out to about 0.7 solar radii , thermal radiation is the primary means of energy transfer. The temperature drops from approximately 7 million to 2 million kelvins with increasing distance from the core. This temperature gradient is less than the value of the adiabatic lapse rate and hence cannot drive convection, which explains why
4674-527: Is ultimately related to the word for sun in other branches of the Indo-European language family, though in most cases a nominative stem with an l is found, rather than the genitive stem in n , as for example in Latin sōl , ancient Greek ἥλιος ( hēlios ), Welsh haul and Czech slunce , as well as (with *l > r ) Sanskrit स्वर् ( svár ) and Persian خور ( xvar ). Indeed,
4797-402: Is wave heating, in which sound, gravitational or magnetohydrodynamic waves are produced by turbulence in the convection zone. These waves travel upward and dissipate in the corona, depositing their energy in the ambient matter in the form of heat. The other is magnetic heating, in which magnetic energy is continuously built up by photospheric motion and released through magnetic reconnection in
4920-539: The Alfvén surface , the boundary separating the corona from the solar wind, defined as where the coronal plasma's Alfvén speed and the large-scale solar wind speed are equal. During the flyby, Parker Solar Probe passed into and out of the corona several times. This proved the predictions that the Alfvén critical surface is not shaped like a smooth ball, but has spikes and valleys that wrinkle its surface. The Sun emits light across
5043-611: The Bodil Pedersen Fonden has also awarded the annual Tycho Brahe Medaljen. The exhibition underwent a major renovation in 2017, and the new exhibition Cosmos (formerly Made in Space) opened in February 2018. The exhibition was made in collaboration with Tony-winning, London based designers, 59 Productions, and was made on a donation from the foundation A.P. Møller Fonden . The exhibition is an interactive and including exhibition, telling
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5166-574: 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
5289-556: 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
5412-633: 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
5535-520: The Parker spiral . Sunspots are visible as dark patches on the Sun's photosphere and correspond to concentrations of magnetic field where convective transport of heat is inhibited from the solar interior to the surface. As a result, sunspots are slightly cooler than the surrounding photosphere, so they appear dark. At a typical solar minimum , few sunspots are visible, and occasionally none can be seen at all. Those that do appear are at high solar latitudes. As
5658-580: 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 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
5781-410: The corona , and the heliosphere . The coolest layer of the Sun is a temperature minimum region extending to about 500 km above the photosphere, and has a temperature of about 4,100 K . This part of the Sun is cool enough to allow for the existence of simple molecules such as carbon monoxide and water. The chromosphere, transition region, and corona are much hotter than the surface of
5904-531: The gravitational collapse of matter within a region of a large molecular cloud . Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System . The central mass became so hot and dense that it eventually initiated nuclear fusion in its core . Every second, the Sun's core fuses about 600 billion kilograms (kg) of hydrogen into helium and converts 4 billion kg of matter into energy . About 4 to 7 billion years from now, when hydrogen fusion in
6027-552: The l -stem survived in Proto-Germanic as well, as * sōwelan , which gave rise to Gothic sauil (alongside sunnō ) and Old Norse prosaic sól (alongside poetic sunna ), and through it the words for sun in the modern Scandinavian languages: Swedish and Danish sol , Icelandic sól , etc. The principal adjectives for the Sun in English are sunny for sunlight and, in technical contexts, solar ( / ˈ s oʊ l ər / ), from Latin sol . From
6150-472: 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 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
6273-428: The photosphere . For the purpose of measurement, the Sun's radius is considered to be the distance from its center to the edge of the photosphere, the apparent visible surface of the Sun. By this measure, the Sun is a near-perfect sphere with an oblateness estimated at 9 millionths, which means that its polar diameter differs from its equatorial diameter by only 10 kilometers (6.2 mi). The tidal effect of
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#17330857665416396-444: The visible spectrum , so its color is white , with a CIE color-space index near (0.3, 0.3), when viewed from space or when the Sun is high in the sky. The Solar radiance per wavelength peaks in the green portion of the spectrum when viewed from space. When the Sun is very low in the sky, atmospheric scattering renders the Sun yellow, red, orange, or magenta, and in rare occasions even green or blue . Some cultures mentally picture
6519-503: 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
6642-461: The Greek helios comes the rare adjective heliac ( / ˈ h iː l i æ k / ). In English, the Greek and Latin words occur in poetry as personifications of the Sun, Helios ( / ˈ h iː l i ə s / ) and Sol ( / ˈ s ɒ l / ), while in science fiction Sol may be used to distinguish the Sun from other stars. The term sol with a lowercase s is used by planetary astronomers for
6765-446: The Solar System . Long-term secular change in sunspot number is thought, by some scientists, to be correlated with long-term change in solar irradiance, which, in turn, might influence Earth's long-term climate. The solar cycle influences space weather conditions, including those surrounding Earth. For example, in the 17th century, the solar cycle appeared to have stopped entirely for several decades; few sunspots were observed during
6888-443: The Sun as yellow and some even red; the cultural reasons for this are debated. The Sun is classed as a G2 star, meaning it is a G-type star , with 2 indicating its surface temperature is in the second range of the G class. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m (watts per square meter) at
7011-424: The Sun extends from the center to about 20–25% of the solar radius. It has a density of up to 150 g/cm (about 150 times the density of water) and a temperature of close to 15.7 million kelvin (K). By contrast, the Sun's surface temperature is about 5800 K . Recent analysis of SOHO mission data favors the idea that the core is rotating faster than the radiative zone outside it. Through most of
7134-688: The Sun will shed its outer layers and become a dense type of cooling star (a white dwarf ), and no longer produce energy by fusion, but will still glow and give off heat from its previous fusion for perhaps trillions of years. After that, it is theorized to become a super dense black dwarf , giving off negligible energy. The English word sun developed from Old English sunne . Cognates appear in other Germanic languages , including West Frisian sinne , Dutch zon , Low German Sünn , Standard German Sonne , Bavarian Sunna , Old Norse sunna , and Gothic sunnō . All these words stem from Proto-Germanic * sunnōn . This
7257-413: The Sun's magnetic field . The Sun's convection zone extends from 0.7 solar radii (500,000 km) to near the surface. In this layer, the solar plasma is not dense or hot enough to transfer the heat energy of the interior outward via radiation. Instead, the density of the plasma is low enough to allow convective currents to develop and move the Sun's energy outward towards its surface. Material heated at
7380-398: The Sun's core by radiation rather than by convection (see Radiative zone below), so the fusion products are not lifted outward by heat; they remain in the core, and gradually an inner core of helium has begun to form that cannot be fused because presently the Sun's core is not hot or dense enough to fuse helium. In the current photosphere, the helium fraction is reduced, and the metallicity
7503-426: The Sun's core diminishes to the point where the Sun is no longer in hydrostatic equilibrium , its core will undergo a marked increase in density and temperature which will cause its outer layers to expand, eventually transforming the Sun into a red giant . This process will make the Sun large enough to render Earth uninhabitable approximately five billion years from the present. After the red giant phase, models suggest
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#17330857665417626-403: The Sun's horizon to Earth's horizon in about 8 minutes and 20 seconds, while light from the closest points of the Sun and Earth takes about two seconds less. The energy of this sunlight supports almost all life on Earth by photosynthesis , and drives Earth's climate and weather. The Sun does not have a definite boundary, but its density decreases exponentially with increasing height above
7749-493: The Sun's life, energy has been produced by nuclear fusion in the core region through the proton–proton chain ; this process converts hydrogen into helium. Currently, 0.8% of the energy generated in the Sun comes from another sequence of fusion reactions called the CNO cycle ; the proportion coming from the CNO cycle is expected to increase as the Sun becomes older and more luminous. The core
7872-551: The Sun's life, they account for 74.9% and 23.8%, respectively, of the mass of the Sun in the photosphere. All heavier elements, called metals in astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%) being the most abundant. The Sun's original chemical composition was inherited from the interstellar medium out of which it formed. Originally it would have been about 71.1% hydrogen, 27.4% helium, and 1.5% heavier elements. The hydrogen and most of
7995-438: The Sun, to reach the surface. Because energy transport in the Sun is a process that involves photons in thermodynamic equilibrium with matter , the time scale of energy transport in the Sun is longer, on the order of 30,000,000 years. This is the time it would take the Sun to return to a stable state if the rate of energy generation in its core were suddenly changed. Electron neutrinos are released by fusion reactions in
8118-402: The Sun. The reason is not well understood, but evidence suggests that Alfvén waves may have enough energy to heat the corona. Above the temperature minimum layer is a layer about 2,000 km thick, dominated by a spectrum of emission and absorption lines. It is called the chromosphere from the Greek root chroma , meaning color, because the chromosphere is visible as a colored flash at
8241-474: 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
8364-486: The beginning and end of total solar eclipses. The temperature of the chromosphere increases gradually with altitude, ranging up to around 20,000 K near the top. In the upper part of the chromosphere helium becomes partially ionized . Above the chromosphere, in a thin (about 200 km ) transition region, the temperature rises rapidly from around 20,000 K in the upper chromosphere to coronal temperatures closer to 1,000,000 K . The temperature increase
8487-460: The core, but, unlike photons, they rarely interact with matter, so almost all are able to escape the Sun immediately. However, measurements of the number of these neutrinos produced in the Sun are lower than theories predict by a factor of 3. In 2001, the discovery of neutrino oscillation resolved the discrepancy: the Sun emits the number of electron neutrinos predicted by the theory, but neutrino detectors were missing 2 ⁄ 3 of them because
8610-495: The core, converting about 3.7 × 10 protons into alpha particles (helium nuclei) every second (out of a total of ~8.9 × 10 free protons in the Sun), or about 6.2 × 10 kg/s . However, each proton (on average) takes around 9 billion years to fuse with another using the PP chain. Fusing four free protons (hydrogen nuclei) into a single alpha particle (helium nucleus) releases around 0.7% of
8733-401: The corona reaches 1,000,000–2,000,000 K . The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere. It is thought that the energy necessary to heat the corona is provided by turbulent motion in the convection zone below the photosphere, and two main mechanisms have been proposed to explain coronal heating. The first
8856-417: 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,
8979-448: 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 ,
9102-400: The duration of a solar day on another planet such as Mars . The astronomical symbol for the Sun is a circle with a center dot, [REDACTED] . It is used for such units as M ☉ ( Solar mass ), R ☉ ( Solar radius ) and L ☉ ( Solar luminosity ). The scientific study of the Sun is called heliology . The Sun is a G-type main-sequence star that makes up about 99.86% of
9225-563: The external poloidal dipolar magnetic field is near its dynamo-cycle minimum strength; but an internal toroidal quadrupolar field, generated through differential rotation within the tachocline, is near its maximum strength. At this point in the dynamo cycle, buoyant upwelling within the convective zone forces emergence of the toroidal magnetic field through the photosphere, giving rise to pairs of sunspots, roughly aligned east–west and having footprints with opposite magnetic polarities. The magnetic polarity of sunspot pairs alternates every solar cycle,
9348-571: 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
9471-477: 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
9594-598: 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
9717-404: The fused mass as energy, so the Sun releases energy at the mass–energy conversion rate of 4.26 billion kg/s (which requires 600 billion kg of hydrogen ), for 384.6 yottawatts ( 3.846 × 10 W ), or 9.192 × 10 megatons of TNT per second. The large power output of the Sun is mainly due to the huge size and density of its core (compared to Earth and objects on Earth), with only
9840-477: The heliosphere, forming the solar magnetic field into a spiral shape, until it impacts the heliopause more than 50 AU from the Sun. In December 2004, the Voyager 1 probe passed through a shock front that is thought to be part of the heliopause. In late 2012, Voyager 1 recorded a marked increase in cosmic ray collisions and a sharp drop in lower energy particles from the solar wind, which suggested that
9963-432: The helium in the Sun would have been produced by Big Bang nucleosynthesis in the first 20 minutes of the universe, and the heavier elements were produced by previous generations of stars before the Sun was formed, and spread into the interstellar medium during the final stages of stellar life and by events such as supernovae . Since the Sun formed, the main fusion process has involved fusing hydrogen into helium. Over
10086-455: 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
10209-603: 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
10332-449: The mass of the Solar System. It has an absolute magnitude of +4.83, estimated to be brighter than about 85% of the stars in the Milky Way , most of which are red dwarfs . It is more massive than 95% of the stars within 7 pc (23 ly). The Sun is a Population I , or heavy-element-rich, star. Its formation approximately 4.6 billion years ago may have been triggered by shockwaves from one or more nearby supernovae . This
10455-444: The neutrinos had changed flavor by the time they were detected. The Sun has a stellar magnetic field that varies across its surface. Its polar field is 1–2 gauss (0.0001–0.0002 T ), whereas the field is typically 3,000 gauss (0.3 T) in features on the Sun called sunspots and 10–100 gauss (0.001–0.01 T) in solar prominences . The magnetic field varies in time and location. The quasi-periodic 11-year solar cycle
10578-402: 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
10701-419: The past 4.6 billion years, the amount of helium and its location within the Sun has gradually changed. The proportion of helium within the core has increased from about 24% to about 60% due to fusion, and some of the helium and heavy elements have settled from the photosphere toward the center of the Sun because of gravity . The proportions of heavier elements are unchanged. Heat is transferred outward from
10824-414: The photospheric surface. Both coronal mass ejections and high-speed streams of solar wind carry plasma and the interplanetary magnetic field outward into the Solar System. The effects of solar activity on Earth include auroras at moderate to high latitudes and the disruption of radio communications and electric power . Solar activity is thought to have played a large role in the formation and evolution of
10947-450: The planets is weak and does not significantly affect the shape of the Sun. The Sun rotates faster at its equator than at its poles . This differential rotation is caused by convective motion due to heat transport and the Coriolis force due to the Sun's rotation. In a frame of reference defined by the stars, the rotational period is approximately 25.6 days at the equator and 33.5 days at
11070-402: 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
11193-473: The poles. Viewed from Earth as it orbits the Sun, the apparent rotational period of the Sun at its equator is about 28 days. Viewed from a vantage point above its north pole, the Sun rotates counterclockwise around its axis of spin. A survey of solar analogs suggest the early Sun was rotating up to ten times faster than it does today. This would have made the surface much more active, with greater X-ray and UV emission. Sun spots would have covered 5–30% of
11316-557: The poloidal to the toroidal field, but with a polarity that is opposite to the previous cycle. The process carries on continuously, and in an idealized, simplified scenario, each 11-year sunspot cycle corresponds to a change, then, in the overall polarity of the Sun's large-scale magnetic field. The Sun's magnetic field leads to many effects that are collectively called solar activity . Solar flares and coronal mass ejections tend to occur at sunspot groups. Slowly changing high-speed streams of solar wind are emitted from coronal holes at
11439-561: 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,
11562-448: The primordial Solar System. Typically, the solar heavy-element abundances described above are measured both by using spectroscopy of the Sun's photosphere and by measuring abundances in meteorites that have never been heated to melting temperatures. These meteorites are thought to retain the composition of the protostellar Sun and are thus not affected by the settling of heavy elements. The two methods generally agree well. The core of
11685-470: The probe had passed through the heliopause and entered the interstellar medium , and indeed did so on August 25, 2012, at approximately 122 astronomical units (18 Tm) from the Sun. The heliosphere has a heliotail which stretches out behind it due to the Sun's peculiar motion through the galaxy. On April 28, 2021, NASA's Parker Solar Probe encountered the specific magnetic and particle conditions at 18.8 solar radii that indicated that it penetrated
11808-423: 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
11931-421: 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
12054-499: 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
12177-428: 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
12300-409: 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
12423-437: The shorter wavelengths. Solar ultraviolet radiation ionizes Earth's dayside upper atmosphere, creating the electrically conducting ionosphere . Ultraviolet light from the Sun has antiseptic properties and can be used to sanitize tools and water. This radiation causes sunburn , and has other biological effects such as the production of vitamin D and sun tanning . It is the main cause of skin cancer . Ultraviolet light
12546-586: 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
12669-809: 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
12792-456: 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
12915-425: The solar cycle progresses toward its maximum , sunspots tend to form closer to the solar equator, a phenomenon known as Spörer's law . The largest sunspots can be tens of thousands of kilometers across. An 11-year sunspot cycle is half of a 22-year Babcock –Leighton dynamo cycle, which corresponds to an oscillatory exchange of energy between toroidal and poloidal solar magnetic fields. At solar-cycle maximum,
13038-476: 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
13161-577: The story of how all of the elements that make up a human originally came from space. Planetarium is home to the largest lunar rock that can be seen outside the US. Weighing more than 200 grams, it was brought back to Earth by the crew on the Apollo 17 mission in 1972. In the Dome Theatre there are shows every day. The centre also screens films. Most are narrated to Danish, but it is possible to have English narration in headphones. During summertime there are normally
13284-417: The surface. The rotation rate was gradually slowed by magnetic braking , as the Sun's magnetic field interacted with the outflowing solar wind. A vestige of this rapid primordial rotation still survives at the Sun's core, which has been found to be rotating at a rate of once per week; four times the mean surface rotation rate. The Sun consists mainly of the elements hydrogen and helium . At this time in
13407-431: The tachocline picks up heat and expands, thereby reducing its density and allowing it to rise. As a result, an orderly motion of the mass develops into thermal cells that carry most of the heat outward to the Sun's photosphere above. Once the material diffusively and radiatively cools just beneath the photospheric surface, its density increases, and it sinks to the base of the convection zone, where it again picks up heat from
13530-424: The temperature of the corona, at least some of its heat is known to be from magnetic reconnection . The corona is the extended atmosphere of the Sun, which has a volume much larger than the volume enclosed by the Sun's photosphere. A flow of plasma outward from the Sun into interplanetary space is the solar wind . The heliosphere, the tenuous outermost atmosphere of the Sun, is filled with solar wind plasma and
13653-422: The tenuous layers above the photosphere. The photosphere has a particle density of ~10 m (about 0.37% of the particle number per volume of Earth's atmosphere at sea level). The photosphere is not fully ionized—the extent of ionization is about 3%, leaving almost all of the hydrogen in atomic form. The Sun's atmosphere is composed of five layers: the photosphere, the chromosphere , the transition region ,
13776-404: The top of the radiative zone and the convective cycle continues. At the photosphere, the temperature has dropped 350-fold to 5,700 K (9,800 °F) and the density to only 0.2 g/m (about 1/10,000 the density of air at sea level, and 1 millionth that of the inner layer of the convective zone). The thermal columns of the convection zone form an imprint on the surface of the Sun giving it
13899-424: The total mass of the Solar System. Roughly three-quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen , carbon , neon , and iron . The Sun is a G-type main-sequence star (G2V), informally called a yellow dwarf , though its light is actually white. It formed approximately 4.6 billion years ago from
14022-418: The transfer of energy through this zone is by radiation instead of thermal convection. Ions of hydrogen and helium emit photons, which travel only a brief distance before being reabsorbed by other ions. The density drops a hundredfold (from 20 000 kg/m to 200 kg/m ) between 0.25 solar radii and 0.7 radii, the top of the radiative zone. The radiative zone and the convective zone are separated by
14145-533: 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. Sun The Sun
14268-432: 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
14391-613: 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
14514-465: 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
14637-407: 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
14760-525: 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
14883-481: 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
15006-398: 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
15129-654: 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
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