Planetariums Around the World

Planetariums Around the World

Twelve Zeiss planetariums were established in Germany and Austria between 1925 and 1928. Rome had one in 1928, and Moscow followed suit in 1929. The Adler Planetarium, Chicago, opened in May 1930, and had such great success that similar projects opened in Philadelphia (1933), Los Angeles and New York (1935), and Pittsburgh (1939). Zeiss universal instruments also were installed during the 1930’s in planetariums in Hamburg, Stockholm (moved to Chapel Hill, Carolina, in 1949), Milan, Brussels, Osaka, Paris, Tokyo.

During World War II most planetariums were either dismantled or destroyed. Soon after the war some of the staff from Carl Zeiss Jena established a rival factory at Oberkochen in West Germany, and since the 1950`s planetarium instruments have emanated from both sources. The instrument of the MacLaughlin planetarium in Toronto, Ontario, Canada was the 14th to leave Carl Zeiss Jena, and the second of its kind to arrive in Canada, the first being the Zeiss Oberkochen instrument of the Dow Planetarium in Montreal, Quebec, Canada.

Zeiss Telescope

Modern Zeiss planetarium instruments, although similar in overall appearance to prewar models, differ from them considerably in points of design. Both Zeiss firms have appreciated the importance of development and improvement in this field. The same is also true of Spitz Laboratories Inc., of Yorklyn, Delaware, a firm which has equipped several hundred small scale planetariums for high-school, colleges, and museums, mainly in the United States. The projector assemblies, compact, relatively inexpensive, and easy to service are designed to operate under domes of the order of 20 and 30 feet in diameter.

In Spitz instruments the star globe takes the form of a hollow dodecahedron or 12-sided figure in the center of which is mounted a single high-intensity point-source of light. The fainter stars are formed by pinholes of various appropriate sizes, while the brighter stars are reproduced by auxiliary lens systems.

The same principle of star formation is used in larger Spitz instruments. The latter, dumb-bell in shape, are installed in major planetariums at Montevideo, Colorado Springs, Colorado, Flint, Michigan while others of intermediate size, capable of additional rotation about a vertical axis are at East Lansing, Michigan; Houston, Texas; Trenton, New Jersey; Salt Lake City, Utah; Bradenton, Florida.

Large planetarium instruments are also made by Goto Optical Manufacturing Company of Tokyo, Japan. Several of these are in use in major planetariums in Japan; one is at St. Louis, Missouri, and another at Armagh Observatory, Northern Ireland.

Custom-made planetariums

This brief survey would not be complete without reference to two unusual but important planetarium instruments, both custom-made and having design features different from those found in the Zeiss models. The first, completed in 1952 for the Morrison Planetarium, San Francisco, took four years to construct and called for the combined skills and efforts of many craftsmen associated with the workshops of the California Academy of Sciences. The hemispheres containing the star field projectors are close to the center of rotation and the sun, moon and planet projectors are at the two ends. The starplates were formed in a most ingenious way. Grains of carborundum selected for size and shape were placed individually on a small glass plate in such a way as to represent in position and size the positions and brightnesses of the various stars in a particular area of the real sky. The plate was then sprayed with opaque black lacquer and when this was dry the tiny grains were removed one by one. The projected stars are therefore irregular in shape and look remarkably like real stars.

The other large custom-made planetarium instrument is found in the Charles Hayden Planetarium, Boston. It was designed and built in Springfield, Massachusetts, by two brothers, Frank and John Korkosz, and departs considerably from the dumb-bell shape. Individual projectors for the 88 brightest stars are distributed over two end hemispheres, each of which contains a 1000-watt light bulb. There are also four quarter-spheres, two for each hemisphere of the sky, in which are 500-watt light bulbs for the stars of the 3d and 4th magnitudes, and 250-watt bulbs for those of the 5th and 6th magnitudes. Altogether, more than 9,600 stars are projected. The instrument has movement in precision, but the moving planetary projectors have yet to be fitted.

(Text published in 1971).