A sound-and-light show doesn't inform or challenge you, it gives you a chance to get into yourself. It's and exercise in orientation, especially when there are 3-D effects as in "Astral Perceptions," on weekend evenings at the Air and Space Museum this month.

It's also an opportunity to make friends with swirly blobs of light in hopes that, as they come smushing in on you, you can hold them back by sheer mental strength. After about 10 minutes you are reassured that the images will stay put on the planetarium dome, and you can relax. Sparkles turn into a swirling galaxy that turns into the planet Saturn, disappearing into vapor.

Now in stage two, you find you may have relaxed too much. If you are prone to temporary suspensions of disbelief or susceptible to hypnotism - in a word, gullible - you find yourself drawn into a throbbing void. Punctuated by synthesizer music, a gyrating sunburst engulfs you.

After this sensation becomes common-place, what one observer calls the Ror schach, or self-revealing stage begins. You try to name what's sweeping above you. It's scary, it's pretty, it's all fragmented. It's a man - it's a bird - it's a men-bird. It's a hand - did I see a hand? - no, it's a space station. It's a hand holding a space station. Projected on the spacearium's spinning backdrop of stars, a kaleidoscope of cattails. Skewered bananas? Kidneys?

The creators of these special effects, John Hardham and Joan Chase, used to tour with rock bands - the Jefferson Airplane, Santana - and had to project on a "postage stamp-size" screen. They find a planetarium dome their ideal visual aid.

By a method they call "media regeneration and recombination," Chase and Hardham have mixed films, slides, videotapes and music. They describe the result: "The abstract is combined with the real in order to communicate the basic underlying patterns and rhythms of the universe."

How true, some would say. Patterns and rhythms - but not much of a plot. Sit back, put on your plastic goggles and prepare to be sucked into the primordial mist.