By Dan Engber

IN THE MOMENTS before the artificial sun sets over a cutout San Francisco skyline, the enormous Star Projector at the center of the California Academy of Sciences' Morrison Planetarium starts moving along its axes. Perched atop two strutted legs like a robotic insect, its black, matte star globes like compound eyes, the projector comes to life, and the star show begins. Half an hour later, during a segment titled "The Future," a video image of the Star Projector appears on the dome against the backdrop of its 3,800 twinkling stars. And then another image appears on top: a red circle with a line through it.

When the California Academy of Sciences closes for renovation Dec. 31, the projector will be retired, after more than 50 years of entertaining almost 10 million visitors. The planetarium is scheduled to reopen in 2008 with a new, multimillion-dollar commercial star projector.

The story of the projector goes back to the early 1940s, when the War Department drafted local amateur astronomers and telescope makers into working at a small optics shop in the academy that was secretly used to repair military equipment. When the academy decided to build a planetarium at the end of WWII, the primary manufacturer of star projectors was in inaccessible, Soviet-controlled territory. So the veterans of the optics shop set about building one themselves, using military-issue lenses and spare parts from Sherman tanks and B-24 bombers. It was completed in 1951 – a 13-foot-long, 5,000-pound device built in-house according to a unique and untested design.

By 1968 astronomy education in San Francisco took to the streets under the direction of John Dobson. An iconoclastic engineer and former monk, he invented the "Dobsonian" telescope – a cheap, easily constructed instrument made of port glass salvaged from naval vessels. Now 88 years old (and still on the lecture circuit), he acknowledges a strong affinity between his guerrilla amateur astronomy movement and the education shows at the Morrison. "It's our planetarium," he says, even though he is no longer permitted to teach there because of his unorthodox views on cosmology. "We made it ourselves. We're recycling the military to educate the public about the universe."

Bing Quock, the planetarium's show producer and assistant chair, who will take over as chair in 2008, is an amateur astronomer with a Dobsonian telescope of his own. Almost all of his star shows for the Morrison have been designed and produced in-house. "These days," Quock says, "the common wisdom seems to be that you bring up a Zeiss projector for two minutes, then go to prerecorded video. Even with a new projector we'll be producing our own shows, with our own content, and live presentations."

Live shows have been a part of the planetarium since it opened. Lew Epstein attended every lecture at the Morrison during its first year and was eventually hired to operate the projector. On one occasion he threw the wrong switch to end the show, sending the sun on a long, slow rise from the west. "It was torture," he said. "The sun was coming up, and I was sweating blood." Even today, visitors can hear coughs over the P.A. system or see the quivering arrow of a hand-held laser pointer. Epstein worries that renovations and upgrades might turn what was once an intimate show into the equivalent of a movie. "I have nothing against movie theaters, but there are enough of those already."

The mission and philosophy of the Morrison will remain unchanged, Quock insists, even with new technologies that allow for preprogrammed, virtual trips through the galaxy. "We don't want to be a joyride," he says. "I get motion sick myself. Why would I put the audience through that?" Quock doesn't question the need for a new projector. "The current projector is showing some signs of age." (During a recent show one of the lids wasn't functioning properly and several stars were projected onto my shirt.) "We're talking about a 50-year-old planetarium without a manual."

So what's going to happen to the Star Projector after New Year's Eve? An e-mail circulating around Bay Area amateur astronomy associations has urged members to contact the academy and make sure it is preserved. "Scientists are very bad at taking care of their historical equipment," says Epstein, a member of the San Francisco Amateur Astronomers since its first meeting. "The old Cyclotron at Berkley was torn apart and thrown away. Old paintings are saved, but old telescopes are taken apart and discarded." The Morrison staff would like to see the projector in use at another planetarium, but any institution with a dome big enough to accommodate it would probably opt for newer technology. The projector has even been offered without success to planetariums in Eastern Europe and Southeast Asia. Epstein and many other Bay Area amateur astronomers would like to see the projector on permanent display at the academy, but no space has been allocated for it in the new building.

Another plan for the old projector would send it to the Smithsonian Institution in Washington, D.C. According to Steven Craig, the Morrison's current chair and the curator of the academy's instrument collection, discussions are under way but no commitment has been made. In the meantime, Craig has contacted an engineer to design and build a frame capable of being stored indefinitely or shipped anywhere in the world. As a Morrison technician and administrator since 1960, Craig has more of a direct, personal connection to the Star Projector than anyone else at the planetarium. He hopes people will come out to see it one last time but "not to lament its passing. They should celebrate its closing and be ready for something new and interesting in its place." Craig, for his part, will retire when the Star Projector is decommissioned. After 19 years as chair, he's decided to step aside. I asked him how he's going to spend his retirement. "I'm a hot-rodder," he says. "In January I'll be riding around in my '32 Ford Coupe."