"Oldest Planetarium Debate"

Zeiss II Planetarium Projector in Theater of the Stars of Buhl Planetarium in Allegheny 

On 1939 October 24, The Buhl Planetarium and Institute of Popular Science opened to the public on the Lower North Side of Pittsburgh, Pennsylvania USA. This institution included the fifth major planetarium in the Americas and the fourth major museum of the Physical Sciences.

Planetaria Opened in the Americas Prior to World War II:

Adler Planetarium and Astronomy Museum, Chicago - 1930
Fels Planetarium [in the Franklin Institute], Philadelphia - 1933
Griffith Observatory and Planetarium - 1935
Hayden Planetarium [in the American Museum of Natural History], New York City - 1935
The Buhl Planetarium and Institute of Popular Science, Pittsburgh - 1939

Oldest Major Museums of the Physical Sciences

Deutsches Museum, Munich, Germany - 1906; 1925
Museum of Science and Industry, Chicago - 1933
Franklin Institute, Philadelphia - 1933
The Buhl Planetarium and Institute of Popular Science, Pittsburgh - 1939-1991

The projection instrument of The Buhl Planetarium and Institute of Popular Science, for its entire service as a museum of the popular sciences, was the Zeiss Mark II Planetarium Projector, manufactured by the Carl Zeiss Optical Works in Jena, Germany. Beginning in the 1960s, as other planetaria retired their original machines [and, in some cases, placed them on exhibit as historic artifacts] and purchased new, more advanced planetarium equipment, Buhl Planetarium kept using their "tried and true" Zeiss II projector.

At least twice, Buhl Planetarium had the opportunity to acquire a newer projector. However, the management of Buhl Planetarium decided to keep their Mark II projector.

In one case, the Mellon family, through their philanthropic foundation, offered to completely renovate and upgrade the Theater of the Stars, including the purchase of a new planetarium projector. The name of the institution would have been changed to the Buhl-Mellon Planetarium. For reasons that are unclear, Buhl Planetarium management did not accept this offer.