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Zeiss Model II Star Projector

The Zeiss Model II Star Projector, originally in use from 1939 to 1991 at the Buhl Planetarium and Institute of Popular Science, is the central “star” of a new exhibition, located in the Atrium on the first floor.

Besides the projector itself, the exhibit offers interactive experiences related to this iconic artifact, including:

• a ‘time machine’ that allows visitors to select any year from 1939 to today and see what was happening in the world of astronomy during that year
• a star clock, on which visitors can pick any date and time and see some of the major constellations in the sky as they would appear in the Pittsburgh sky that night
• an exhibit demonstrating the relative sizes of the planets
• a 1000-watt bulb that was used in the Zeiss Projector
• original Buhl Planetarium seats

The Zeiss Model II Star Projector was the workhorse of the Buhl Planetarium from 1939 until Carnegie Science Center opened in 1991, after which it was reserved for special programming. Complex clockwork mechanisms allowed it to accurately project the stars as they would appear at any point in time, from any place on the Earth. Among many other notable uses, Air Corps pilots used the Buhl’s Zeiss Model II Projector to train during World War II. It was officially retired in 1994. The new Zeiss Model II Star Projector exhibition was made possible by a $100,000 gift from the Buhl Foundation.

Planetarium history

The Buhl Foundation was created in 1927 in honor of the late Henry Buhl, Jr., to lead several civic projects, including the construction of a planetarium. When it opened in October 1939, the Buhl Planetarium was the fifth major planetarium in the United States-joining those in Chicago, New York, Los Angeles, and Philadelphia. It featured a 492-seat “Theater of the Stars” and boasted a 65-foot-diameter dome. For decades it served millions of visitors spanning several generations, from the merely curious to future NASA astronauts.

The original building was named for Henry Buhl, Jr., who built his fortune in retail with his partner, Russell Boggs. The Boggs and Buhl Department Store provided the finer things for the residents of (then) Allegheny City and the entire region. The store, located near present-day PNC Park, closed in 1958.

Since 1991, the Buhl legacy and mission has continued at Carnegie Science Center, thanks to the leadership support of the Buhl Foundation for the Buhl Digital Planetarium and related astronomy programming. Carnegie Science Center has established itself internationally as a leading creator of quality planetarium shows with innovative content. More than 1,000 programs have been distributed throughout the United States and across four continents. These shows have been translated into 18 languages. Buhl Planetarium productions have become so highly regarded that they have attracted the talents of futurist and science-fiction author Sir Arthur C. Clarke, actor Leonard Nimoy (who narrated the shows New Cosmos and The Search for Life in the Universe, respectively), NASA, the Space Telescope Science Institute (STScI, a branch of NASA), The Center for Light Microscope Imaging and Biotechnology, the Pittsburgh Tissue Engineering Initiative (PTEI), and Family Communications (producer of Mister Rogers’ Neighborhood).

In September 2006, the Science Center installed a full-dome digital projection system purchased with a $1 million gift from the Buhl Foundation. The visual impact and programming flexibility of this system vastly expands the nature and breadth of subject matter showcased in the planetarium. Although the new system is used most extensively for astronomy programs, it also can be used for scientific fields, particularly the biological sciences, chemistry, and engineering.

The Zeiss Model II Star Projector

The Zeiss Model II Star Projector was constructed by Germany’s Zeiss Optical Works. The iconic projector, nicknamed “Jake” by Buhl Planetarium staff, was the workhorse of the Buhl Planetarium from 1939 until Carnegie Science Center opened in 1991, after which it was reserved for special programming. By that time, Zeiss Optical Works had ceased making parts for the II models, and Buhl Planetarium staff had to custom-make replacements to keep the stars shining for visitors. It was officially retired in 1994.

The Zeiss Model II Star Projector used a star globe-a high-tech flashlight-at each end, one projecting the stars of the Northern Hemisphere, and one the stars of the Southern. Complex clockwork mechanisms allowed it to accurately project the stars at any point in time, from any place on the Earth. It would even correct for the planet’s precession-the slight wobble in its rotation that causes ‘true north’ to change over time.

The Zeiss Model II Star Projector used a 1000-watt incandescent bulb. The filament’s position and shape were critical to making sure the light projection that created the stars was accurate. Additional projection spheres were used to add other stars that were not possible with ‘blind spots’ on the larger star balls. The projector was known worldwide for its accuracy and advanced technologies.