Planetarium (Greek-Latin planetary machine) originally referred to a device to illustrate the course of the planet. Until the 19th century it was understood to be a small mechanical device that is now known as an " orrery ". The modern planetarium is a building with a hemispherical dome, on the inner surface of which images of the starry sky are generated by a special projector . This type of planetarium is called a projection planetarium. One of the essential features is that the projector can display the daily and annual movements at any time and for any geographical location. The inventor of the modern projection planetarium is considered to be the physicist Walther Bauersfeld , who developed and built it in 1919 on behalf of Carl Zeiss Jena . The projection planetarium is not to be confused with an observatory . The former creates a simulated starry sky, while real celestial objects can be observed in an observatory.
Another instrument for observing real celestial objects and for finding them is the handheld planetarium, a small, hand-held computer with GPS receiver, position sensors and sighting device. With the handheld planetarium celestial objects such as stars and planets in the real starry sky are aimed at, the handheld planetarium identifies the objects and provides further audio-visual information via headphones and display.
There are over 3,200 projection planetariums worldwide, but this number is probably too low as many school planetariums are mainly used internally and little information is available about them. At least 1500 planetariums are known in the USA. The largest and most modern houses are in Japan and Australia. The Zeiss Planetarium in Jena (D) is the longest-serving, but still one of the most modern planetariums in the world, which has been in operation since June 18, 1926 until today. More than 100 million visitors visit a planetarium every year.
Over 450 planetariums are listed in Europe, including an unknown number of tented planetariums. The largest European buildings with a dome diameter of more than 23 m are located in: Brussels (BE), Prague (CZ), Jena (DE), Copenhagen (DK), Valencia (ES), Athens (GR), Budapest (HU), Chorzów (PL), Częstochowa (PL), Lisbon (PT), Moscow (RU), Saint Petersburg (RU), Stockholm (SE) and Kiev (UA).
Germany, Austria, Switzerland
There are around 100 planetariums in Germany (as of June 30, 2007). There are also two concrete new construction projects: the Galileum Solingen and the replacement building for the space flight planetarium “Sigmund Jähn” in Halle (Saale) .
In Austria there is a large planetarium in Vienna ( Wiener Planetarium ), a medium planetarium in Klagenfurt and three small planetariums (Judenburg, Schwaz and Vienna). On September 11, 2006 , the Zeiss Planetarium Schwaz was the first planetarium in the world to receive a Spacegate Quinto full-dome video system . On November 8, 2006, another full-dome planetarium was opened in Judenburg , the “ Star Tower ”. The newest planetarium in Austria is the digital planetarium in the Natural History Museum in Vienna. It was opened in September 2014 on the occasion of the museum's 125th anniversary and is a full-dome planetarium of the latest generation. The small planetarium in Königsleiten, the highest planetarium in Europe, was finally closed in spring 2016. In December 2017, the astronomer and science mediator Ruth Grützbauch started the mobile, inflatable pop-up planetarium Public Space with a 5 m diameter for up to 30 children in Vienna with a cargo bike and visited schools, kindergartens and events.
In Switzerland, the Verkehrshaus in Lucerne has an 18 m large planetarium, the city of Kreuzlingen has a planetarium with a 10 m dome. There are also five small planetariums. A new small planetarium was opened in Sion in autumn 2018.
In 2011 the Gesellschaft Deutschsprachiger Planetariums e. V. founded as the successor organization of the Council of German Planetariums , which previously only existed informally, and the Working Group of German-speaking Planetariums . The GDP conference, which takes place annually in April / May, is a kind of industry meeting of the planetariums and the companies active in this area. Within the GDP there are several working groups that deal with specific topics, e.g. B. Planetarium didactics and planetarium management. The next GDP conferences will take place in Kiel (2019) and Solingen (2020).
Mobile planetariums and home planetariums
In addition to the stationary planetariums with their large devices and correspondingly large and massive domes, there are also a number of small and mobile solutions. A mobile planetarium consists i. d. Usually a more or less handy projector and a mostly inflatable dome. Dome sizes of around 2.5 to 7 meters in diameter are used. There are many different approaches to the projection apparatus. With purely optical devices, mostly only the starry sky is shown, here sometimes only for one hemisphere. But there are also quite complex devices with sun, moon and planet projectors. What all these devices lack is the automatic control of these additional projectors. Supported by the rapid development of computers and digital projectors (so-called projectors), the digital planetarium has also recently become established. The image quality is not comparable to the impression of optically projected stars, but absolutely all aspects of the starry sky can be explained, i.e. planetary movements, eclipses, passages, etc.
A new generation of portable planetariums is being developed by the Japanese planetarium builder Takayuki Ohira. Its planetariums are used at events such as B. the Aichi World Expo 2006 their application. In addition to the professional Astroliner and Megastar lines, Takayuki Ohira launched the first home planetarium under the name Sega Homestar in August 2006 in collaboration with the Sega Toys company. In handbag format, it projects a realistic starry sky of up to 60,000 stars onto the ceiling or wall for the hobby area. The accuracy and programmability of a professional projection planetarium cannot be achieved with such a significantly cheaper home device.
Larger projectors are used in mobile “inflatable” planetariums. These consist of a round dome tent in which a compressor generates a slight overpressure that keeps it upright. Inside there is space for up to 55 people, who are sitting on cushions throughout the tent. The projector is in the middle of the small dome, where the presenter also sits. Such planetariums are mostly operated by individuals who book themselves and their planetarium for events of all kinds.
One example of a mobile planetarium that does not depend on a hall with a dome-shaped ceiling is the Zurich Planetarium . The view of the starry sky is projected onto a screen by computer-controlled projectors .
Equipment and technology
Auditorium and dome
Many cities have public planetariums with presentations for all ages. Similar to the cinema , the viewer takes a seat in the interior of the dome. To ensure a good and ergonomic all-round view of the artificial starry sky on the dome , the seats underneath are often rotatable. The classic seating arrangement consists of concentric rows of seats around the central star projector. In newer buildings, a unidirectional seating arrangement similar to that of a cinema is increasingly being installed. The dome is often inclined by up to 30 °, which means that parts of the floor can also be seen during film presentations without the image having to be distorted or tilted. The dome itself is usually made of bent sheet metal. Like a cinema screen, it can be perforated to allow the sound from speakers behind it to pass through .
Today's image of a planetarium projector is shaped by opto-mechanical devices in the shape of a ball or dumbbell in the center of the dome. The star field projectors are the core of the system. Older devices show the stars through pinholes, while newer generations from Carl Zeiss work with fiber optic technology. Changeable objects like the sun , moon and planets are generated by additional projectors. This allows the shape of the starry sky and the apparent movement of the stars and planets to one another, over the day, over years or centuries. By rotating around the main axis, the time of day or the geographical longitude of the location can be changed; by tilting it around a horizontal axis, the geographical latitude can be determined. Other projectors can display the constellations and their names, the Milky Way and other nebula-like objects .
The model IX "Universarium" from Carl Zeiss Jena is considered to be the most modern star projector in the world . The first model of this kind in Europe was installed in the Bochum planetarium in 2000 . After Stuttgart in 2001, the Universarium was also set up in the Vienna Planetarium and Mannheim in 2002 , followed by the Hamburg Planetarium in 2003 and Berlin in 2016. The Zeiss Planetarium Jena was equipped in October 2006 with an all-dome laser image projection system ("All Dome Laser Image Projection"), as is also used in the Beijing planetarium. This projects a seamless dome image with a significantly improved color and contrast representation.
In Hamburg Planetarium and Mediendom Kiel for the first time in Germany, a 360 ° -Video projection with the system Digistar 3 of the company Evans & Sutherland used. For the first time, this simulator enables the free visualization of complex content beyond astronomy.
Often the star projection is supplemented by slide projectors . These are usually housed in the side walls below the dome. In addition to simple projectors for lecture purposes, systems with several coupled slide projectors are used; a distinction is made between two variants:
With the slide projectors u. a. the silhouette of a city and the twilight are represented. In order to be able to cross-fade between panoramas and full-dome images, several projection sets are often installed. Therefore, 20 or more slide projectors installed in planetariums are not uncommon.
Video projectors are used to be able to display moving images . In order to offer all viewers a good view, these are often carried out several times. Tube projectors are mostly used because of the better black value . Only the newer generations of LCD and DLP devices meet this requirement satisfactorily.
Lasers offer high light intensity, brilliant colors and maximum sharpness. In large houses, they are therefore used as image or video projectors (e.g. Zeiss ZULIP ). The latest generations of laser projectors ( Zeiss ADLIP , E&S Digistar Laser ) are able to completely display the dome and display stars in a quality comparable to that of an optomechanical star projector.
Show lasers, like those found in discos, are also used and - combined with fog machines - are used for music and entertainment programs. The system is often supplemented by headlights, scanners , stroboscopes, etc.
Full dome video
Due to digitization and the ever increasing memory and computing power, it has been possible for some years to display moving images that fill the dome . With such a system, virtually any content can be projected onto the dome; making the planetarium a real multimedia theater. In this way it is z. B. possible to simulate flights between the stars, roller coaster rides or dives in the deep sea.
The image does not come from the film as in a dome cinema, but is usually displayed by several synchronously running video projectors. Two operating modes are possible, some of which can be combined:
- Full dome video
- Real-time images generated by high-performance graphics processors - this variant even enables objects to be controlled interactively using the keyboard, mouse or joystick.
Even if most houses are still equipped with classic stereo systems, the larger planetariums in particular have reacted to the trend towards multi-channel sound and installed corresponding 5.1 or 7.1-channel systems. In the meantime the first approaches to real 3-dimensional sound systems can even be found, e.g. B. in the Adler Planetarium in Chicago. In Germany, 3D audio systems can be found in the domes of the planetariums in Jena, Hamburg and Bochum and in the media dome of the Kiel University of Applied Sciences. The latter four systems are based on developments by the Fraunhofer Institute for Digital Media Technology (IDMT) in Ilmenau.
With armillary spheres , the orbits are depicted with metal rings.
In the giant globe of Gottorf there is a model of the old, geocentric worldview according to Ptolemy . It was built between 1650 and 1664 and is considered the oldest accessible planetarium. There are four such hollow globes around the world .
An old mechanical planetarium is located in Franeker ( Friesland , Netherlands ). This precisely moving model of the planetary system is located in the living room of a beautiful Frisian canal house in Franeker. It was made between 1774 and 1781 by the wool comb Eise Eisinga : On May 8th 1774 there was a confluence of planets. It was claimed that these planets would collide. This should throw the earth out of its orbit and burn it in the sun. Eise Eisinga wanted to use the device to show that there was no need to panic.
The world's first projection planetarium was presented to the public on October 21, 1923 in the Deutsches Museum in Munich. Two months earlier, it was tested on a 16-meter dome at the Zeiss plant in Jena. Before the final installation, it was first sent again from Munich to Jena for completion and then officially put into operation in Munich on May 7, 1925.
The Barmen Planetarium was a planetarium opened in 1926 in the Barmen facilities in Barmen, a current district of Wuppertal. When it opened, it was, apart from a test installation by the projector manufacturer in Munich, the first planetarium in the world and one of the largest of its kind.
Projector technology was later decisively further developed in Jena and the technical equipment of planetariums all over the world developed into an important export product for VEB Carl Zeiss Jena .
Astronomy computer programs
There are now various astronomy programs that offer similar display options on the computer monitor as a planetarium.
Often you can move and navigate virtually in space between the stars. For this purpose, speed and distances are given so that you can explore the spatial arrangement of the most important stars yourself.
The latest development are so-called hand planetariums. These are small independent computers with GPS receivers for determining the position and time, magnetic sensors for determining the azimuth , accelerometers for determining the elevation , direction finding device in the form of a simple tube or a rear sight and a small screen . They are intended for use under the real starry sky. With the help of the built-in sensors it is determined which celestial object the hand planetarium is aimed at. Hand planetariums have different operating modes depending on the model. For all of them, celestial objects can be aimed at, they are identified at the push of a button and for all objects further information is output on the screen and for the most important objects audio information is output via headphones . In another mode, celestial objects can be entered and searched for with the help of directional information on the monitor or on the sights. One of the models is able to align telescopes with goto mounts on the targeted object. Another model can be mounted on special telescopes made of non-magnetic materials such as a finderscope .
In principle, hand-held planetariums offer, depending on the audiovisual information and databases available on the small computer, similar possibilities to explore space as projection planetariums with one important restriction: Only the currently visible starry sky is available. New information and new training programs can be transferred to the handheld planetarium at any time using a software update. Hand planetariums are ideal for self-study of the starry sky. They offer, so to speak, guided tours through the visible celestial objects. The most important operating mode is the help for finding the objects and the information then displayed.
- Yann Rocher (Ed.), Globes. Architecture et sciences explorers le monde . Norma / Cité de l'architecture, Paris, 2017.
- Boris Goesl, Hans-Christian von Herrmann, Kohei Suzuki (eds.): To the planetarium. Studies in the history of knowledge . Paderborn 2018, ISBN 978-3-7705-5971-8 .
- List of planetariums in Germany
- Hollow globe
- Astronomy program
- Star map (There are rotatable star maps in which the sky section currently appearing in the course of the year and day, typical for a fixed mean geographical latitude, e.g. 45 ° north, can be displayed, and those with luminescent star points - after exposure with a hand lamp. )
- Cartes du Ciel - Freeware PC planetarium software with extensive catalogs and plug-in for, for example, Meade Autostar controls
- Celestia - 3d cosmos simulator with thousands of objects, expandable with various plugins - open source
- Stellarium - Realistic representation of the starry sky with free choice of location and time as well as numerous photos of celestial objects - Open Source
- Planetariums Worldwide list APLF-IPS (English)
- Society of German-speaking planetariums
- International Planetarium Society (English)
- Planetariums in Switzerland
- Articles about planetariums and FE dome projection
- Society of Austrian Planetariums
- In its original use; see planetarium . In: Gabriel Christoph Benjamin Busch : Handbook of inventions: Tenth partly Zweyte division, the letters P and Q containing . Wittekindt, 1820, p. 366.
- Status: end of 2006; Source: LochNessProductions
- The world machine . ISBN 978-3-9811120-2-3 , pp. 145-146
- List of planetariums in Germany ( Memento of December 30, 2011 in the Internet Archive ) and Europe ( Memento of December 14, 2009 in the Internet Archive ), the original retrieved on July 5, 2008
- www.planetarium.at ( Memento from May 24, 2007 in the Internet Archive ) (originally accessed on September 13, 2009)
- Susanne M. Hoffmann: Planetarium-Observatory Königsleiten finally closed . Article in the blog portal SciLogs from May 11, 2016. Retrieved on December 9, 2017.
- Inflatable planetarium on tour orf.at, February 12, 2018, accessed February 19, 2018.
- Starry sky for everyone: The Pop-up Planetarium "Public Space" scienceblogs.de/astrodicticum-simplex, December 14, 2017, accessed February 19, 2018.
- Museum of Transport in Lucerne
- Kreuzlingen planetarium and observatory
- Planétarium Sion - Valais . Site of the Sion planetarium in Valais (French).
- Starsight , No. 3/2008, p. 10. Manufacturer's website Celesstron SkyScout ( Memento from September 29, 2009 in the Internet Archive ), Meade mySKY ( Memento from September 6, 2011 in the Internet Archive )