Planetarium
A planetarium , is a theater of the type “ Cinema ”, whose screen is a dome a few meters in diameter and dedicated to the representation of the starry sky. One can attend a spectacle representing to with it a topic directly related to the Astronomie, thanks to a projector, the simulator of stars or “ planétaire ”, conceived to represent the starry vault, the constellations, the movement of the Planet S in the sky, etc
The term of planetarium is ambiguous in the sense that it indicates at the same time the apparatus which simulates the sky and the room in which this apparatus functions. The current trend would be to hold the " term; planétarium" in the room and to use those of " simulateur" or of " planétaire" for the projector.
History
The idea to represent the sky artificially is very old. It seems that, as of Antiquity, one forged this word to indicate a kind of model representing the Sun, the Moon and planets.The first models, which one could indicate by planetary ( orrery , in English), made it possible to model the movements of planets around a fixed Sun: the stars were not present, but could be suggested by drawings placed at the periphery. This type of planetariums, still indicated by planetariums copernicians (or heliocentric) did not make it possible to emerge towards the theater whom we know today.
In addition, one also sought to represent stars via more or less large celestial spheres.
In a case as in the other the spectator was external: he saw planets turning around the Sun, or stars on a sphere in front of him (the figures of the constellations were thus reversed).
The first planetarium
On the initiative of the German astronomer max Wolf, then director of the observatory of Heidelberg, and of the founder of the technical Museum of Munich (the Deutsches Museum) Oskar von Miller, the idea of a planetarium galiléen (or ptolémaïque ) was proposed since 1913 at the company Carl Zeiss. Its director, Walter Bauersfeld, built a first planetarium, prototype of all those which we know today. The first version of this aircraft was installed in August 1923 on the roofs of the Zeiss factory to Jena, in Germany. This first version was assembled under a dome 16 m in diameter.October 21st, 1923 this apparatus was presented to the public of Munich. There there remained only a few weeks, and went back to Jena to be finished.
It is finally on May 7th, 1925 that the first planetarium was installed definitively on the roof of Deutsches Museum.
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