Star projector returns to the spotlight at Pittsburgh's science center


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In the old days, the Zeiss Model II Star Projector elicited oohs and ahs from the kid-dominated crowds as it rose up from the basement of Buhl Planetarium on a special elevator into the domed Theater of the Stars.

Weighing some 6,000 pounds, it looked like some giant ant from outer space as it moved slowly on the lift designed to protect its delicate lenses.

To the folks from Buhl, however, it was just "Jake" -- a mechanical friend that wore balloons on its birthdays and the workhorse of the sky shows viewed by millions of people at the planetarium from 1939 through 1991. It then was reserved for special programming until it was retired officially in 1994.

Now the Zeiss is back in an interesting look-back exhibit at the Carnegie Science Center.

It doesn't travel by elevator; rather it's got a stationary home in the center's atrium. Nor does it have the room to project sky shows as it did within the Buhl's 65-foot-diameter dome.

But there's still plenty of history -- and astronomy -- to be learned from the 71-year-old artifact constructed in Germany by Zeiss Optical Works.

The Zeiss used what the Carnegie said was called a "star ball," or a sort of high-tech flashlight, at each end. One end projected the stars of the Northern Hemisphere and one the stars of the Southern. Complex clockwork mechanisms then enabled it to project accurately the stars at any time from any point on Earth.

At its new display, the projector still "spins" through a speeded-up north-to-south cycle, allowing visitors to see how "baby-doll lids" opened and closed on smaller Northern and Southern hemisphere lenses.

Signage that fronts the Zeiss tells viewers that it was used to teach Army Air Corps pilots celestial navigation during World War II. And on that display is one of the huge 1,000-watt incandescent bulbs used in the projector. The filament's position and shape were critical to ensuring the light projection that created the stars was accurate.

But beside the Zeiss, the heart of the new astronomy exhibit is a sort of "time machine" that allows visitors to select any year from 1939 through today and see what was happening in science, particularly space science, at that time.

In 1940, visitors learn, carbon-14 was discovered while here at home the first Pittsburgh Regional School Science and Engineering Fair was held.

For 1947, the "time machine" tells visitors that ace pilot Chuck Yeager of "The Right Stuff" movie fame broke the sound barrier while Buhl hosted an annual show of more than 100 aquariums.

In 1952, the Viking Rocket Program was in progress. There were 12 Viking rockets flown between 1949 and 1955.

To the side of the Zeiss and the "time machine" is a small zoetrope, a device that produces an illusion of action from a spinning succession of pictures. This particular, cylindrical zoetrope shows "Jake" coming into the Theater of the Stars on his elevator.

On the ramp leading up to the second floor, Carnegie Science has put up a mural showing the solar system in all of its vivid colors. Portrayed to scale, it particularly brings home Earth's relatively small size compared to Jupiter, which has a diameter 10 times as great.

The exhibit was financed by a $100,000 gift from the Buhl Foundation.


Pohla Smith: psmith@post-gazette.com or 412-263-1228. First Published July 14, 2010 4:00 AM


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