(FORTUNE Magazine) – What a bummer. After 28 years, 45 cities, and more than 20 million blown minds, Laserium--that light and music phantasma that brought suburban stoners flocking to the local planetarium by the vanful--has fired its last beam. Though it was never to flourish the way it did when Earth Shoes walked the land, Laserium hung in there far longer than other '70s fads.

"We were the first to do laser entertainment," boasts 62-year-old Ivan Dryer, Laserium's creator. A former astronomy major turned filmmaker, Dryer recalls how "I was bored with the blobby light shows they had in the '60s." In 1970 a Caltech professor, Elsa Garmire, introduced him to the laser, whose uncluttered light waves produce colors of previously unimaginable purity. Futzing off-hours with university equipment, Garmire created the shapes and patterns that would come to be known as laser art. When Dryer tried filming the effects to the accompaniment of music, the hues lost their visceral wallop. And that's when the idea of a live show hit him (and Laserium was almost always performed live, with a laserist creating retina-searing images for the audience in real time).

Although it took three years, he finally persuaded his former employer, L.A.'s Griffith Observatory, to turn over its 600-seat planetarium for a test run of four Monday nights. On Nov. 19, 1973, a half-filled house watched a group of dazzlingly red, yellow, blue, and green circles dance on the ceiling to the accompaniment of "The Blue Danube." A month later he had to turn away 500 people.

At first, there were glitches, but the audience didn't mind "if we made mistakes on the beat," says Dryer. Technology improved, skills advanced, and newer shows were launched--like Laserium II, Laserock (Genesis, Fleetwood Mac, the Doobie Brothers), and the Star Wars-inspired Laserium Starship. "Against all the advice we'd been given," he says, "we were able to demonstrate that there was a mass market for a largely abstract entertainment."

But the times they do a-change. Sure, Dryer tried to stay current, introducing Laser Wave (Devo, A Flock of Seagulls, etc.), Pink Floyd's The Wall, even "family-oriented" fare such as Laser Holiday 3-D. And apparently it remained necessary to open the show with the traditional wink-wink announcement: "There is to be no smoking of anything in the planetarium." But by the time the grunge-era Lollapalaser came around, the franchise had become a relic. "The peak was 1978, and it was a slow attrition from there," Dryer says. "Reagan was terrible for us." New York City's Hayden Planetarium jettisoned the show in 1982. Boston and San Diego went laser-free in the mid-1990s. And last month, in its birthplace, L.A., the laser light dimmed for good.

It's unfair to hang it all on Republicans, of course. The once radical form of art simply evolved away from the observatories and became a staple of rock concerts, theme parks, auto shows, and any tacky thing that needed to shout "extravaganza."

And like videocameras and day trading, lasers themselves were becoming more accessible to the common man. By the latter years mischief was wrought by would-be artists sneaking in handheld laser pointers. "We'd have to get the ushers to help us track them down," says ex-laserist Ron Hipschman, who worked the controls at San Francisco's Morrison Planetarium, where the show survived until last year.

So even though the nation's planetariums will confine themselves to exhibiting the known cosmos, laser light shows will live long and prosper--just elsewhere. This spring or summer, Dryer himself is launching a venture in Hollywood called the Laserium Cyberdome, an "interactive show experience," which he hopes to roll out nationwide. "Because of the Light Dancer sensors in the floor, a person who's moving around the Cyberdome will affect the image that is projected overhead, and also the sound or music," he promises. "Essentially the audience will no longer be the audience; they will be co-creating the experience." Sounds far out, but it remains to be seen whether all that 21st-century gadgetry can recapture the naive wonder first elicited by Laserium I's waltzing circles.

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