Initially, the planetarium name was granted to a device constructed by the factory of optical instruments and photographic of Kart Zeiss, of Jena, in Germany, although at the same time this word is used to designate the building in cupola form, and also the room in which it settles an apparatus projector. This apparatus allows that we see in the vault, just like if we were in a cinema, a reproduction of the firmament: the sun, the moon, the stars and constellations, thus like its diverse movements.
The mentioned camera or apparatus projector is placed in center of the room, that has a hemispheric form and whose armchairs are arranged in circular rows and the images are reflected in the cupola. The projector current Zeiss is resembled, in certain way, to gymnasium weights, with two iron spheres, one of each end, and each one of them contains 16 units of projection. As well, these units present/display a thin metallic plate, with opening as large as an end of pin, practiced with rigorous precision in 65 different proportions, to the object to project the images of the starred sky, on guard correct, as small discs of size and brightness corresponding to their real appearance in the firmament.
Let us see now as it is the power of this camera: the rays that it sends to his great circular screen are produced by an hourglass of about 1,000 watts in each sphere; and when shining through each opening, they focus in the superior capsule, thanks to a system of called lenses Ressar. And if we consider that 32 units of projection exist, whereas in a current cinema it exists, naturally, a single camera, then we can form an approximated idea of the complexity of its mechanism and its operation.
In its important work of revolutionibus orbium coelestium, published in 1543, Copernico it sent the concept - not thought then that the planetary system to which belongs the Earth has by center to the Sun. This thesis I almost take a forever in being accepted, and on her basaronse the Dutch Huygens and the Roemer Danish to construct, during century XVII, the first models of planetariums. With such aim they used provided globes, to relative distances, to represent planets in whatever one talks about to its natural size and its respective real positions.
When in course of the year 1913 order to Zeiss the construction of a better device, surgeries than the stars would have to imagine by means of fixed or movable electrical lamps on a rotator cupola. Of any way, this proposal quickly was discarded in favor of another one, had to optical doctor Bauersfeld, in who the images of the celestial bodies were projected by individual rays of light on a fixed cupola. The resulting apparatus I mean a remarkable success for its creator. It was deduced that if the planned vault could reach the 50 meters of diameter, the serious aspect extremely similar to the one of the true sky. And, in effect, thus it was. The planetarium fulfills its objectives of almost perfect way today.