A planetarium is a theater built for presenting shows about astronomy and the night sky. The plural of planetarium is planetariums or planetaria.

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A typical Planetarium building
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McDonnell Planetarium In St. Louis, Missouri
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Planetarium dome, close up
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Cruise liner Queen Mary 2 Planetarium


Planetariums typically use a large dome shape for the projection screen, with inclined chairs for comfortable viewing "straight up". A large projector in the center of the dome creates the scene, using a number of movable projectors projecting the images of stars or planets onto the screen. The various projectors are geared to provide an accurate relative motion of the sky, and the entire system can be set to display the sky at any point in time.


Archimedes is attributed with possessing a primitive planetarium device that could predict the movements of the Sun, the Moon and the planets. The discovery of the Antikythera mechanism proved that such devices already existed during antiquity.

The first modern planetarium projectors were designed and built by Carl Zeiss in 1924, and have grown more complex. Smaller projectors include a set of fixed stars, Sun, Moon, and planets, and various nebulae. Larger machines also include comets and a far greater selection of stars. Additional projectors can be added to show twilight around the outside of the screen (complete with city or country scenes) as well as the Milky Way. Still others add coordinate lines and constellations, photographic slides, laser displays, and other images. The OmniMax movie system (now known as IMAX Dome) was originally designed to operate on planetarium screens.

In recent years, planetariums — or dome theaters — have broadened their offerings to include wide-screen or "wraparound" films, all-sky video, and laser shows that combine music with laser-drawn patterns. The newest generation of planetariums has moved to a fully digital projection system, in which a single large projector with a fish eye lens, or a system of digital video projectors around the edge of the dome, are used to create any scene provided to it from a computer. This gives the operator tremendous flexibility in showing not only the modern night sky as visible from Earth, but any other image they wish (including the night sky as visible from points far distant in space and time).

A portable class of planetariums can be set up for programs at schools, for example, on a temporary basis. Easily transported and quickly erected inflatable structures have been used for this purpose.

The term "planetarium" can also be used to describe the projector itself, or other devices to illustrate the solar system, like a computer simulation or an orrery.

Notable planetariums

Planetarium computer software

See also

External links

de:Planetarium eo:Planetario fr:Plantarium it:Planetario he:פלנטריום nl:Planetarium ja:プラネタリウム pt:Planetrio sv:Planetarium


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