Despite its celestial object, "Stars" never leaves earth orbit. It's a look at man looking skyward.

You enter the National Air and Space Museum's new exhibit through synthetic boulders modeled after an arch from Stonehenge; in the receiving line stands a massive Ming sundial: a calibrated disc on the back of a grinning dragon.

Forging on, past the sundial's modern counterpart -- the pulsing signal of an atomic clock, transmitted by Navy satellite -- you're invited to press a button that activates Dick Haymes singing "Stardust," Elton John doing "Don't Let the Sun Go Down on Me," and Perry Como crooning "Catch a Falling Star." Turn around, and you'll likely catch the star-shaped logo of the American Cafe.

Those who trek to "Stars" expecting space odysseys or returning Jedi will be cosmically disappointed. But those who want wisdom or whimsy will be generally rewarded.

For a survey of our attempts through the ages to make the infinite universe manageable -- to define the undefinable by science, art and even commerce -- laymen could hardly improve on this engaging and handsome show. Although thin on math and physics, and a near-total blank on cosmology, it's fat on buttons, lights and hardware -- and, thus, heaps of fun.

There are satellites aplenty hanging overhead, a 3-D depiction of astronauts floating outside Skylab, and two scale models of Space Telescope, the exhibition's leitmotif. A $1-billion NASA project, the telescope is scheduled to be shuttled into a 300-mile orbit in 1985, affording the best view ever of the great beyond.

The show's subtitle is "From Stonehenge to the Space Telescope," but the displays are aimed largely at the last 50 years, during which observational astronomy has all but forsaken the visible universe for the invisible realms of ultraviolet, radio, infrared and X-ray emissions.

"I'm very pleased with it," said Martin Harwit, a visiting infrared astronomer from Cornell University. He was talking about a 3-D cutaway of a Learjet, wherein a crouching mannequin labors at an infrared telescope. "I work in the Learjet, and most people don't know what it's like in there. Now everyone can see exactly what the infrared astronomer has to contend with."

There is some hard science here for the serious-minded -- what precisely are stars made of? how do they form, thrive and die? -- but also gewgaws enough for the unrepentant gadget-freak.

One of these, "Fusion Energy," is a computer game a la Space Invaders, wherein players heat speeding hydrogen atoms by bombarding them with others from an emplacement on screen. The atoms reach critical temperature when sufficient hits are scored; the hydrogen fuses into helium, there's a blinding flash of energy, and the screen proclaims: "CONGRATULATIONS! YOU HAVE ACHIEVED FUSION IGNITION."

Another computerized display, titled "Real or Apparent," shows, at intervals of 20,000 years, how stars change their relative positions as seen from earth; at still another terminal, you punch in your age, and the computer spits out the name of the star the equivalent number of light-years away -- mine was Vega -- and shows you where it is on the accompanying sky chart.

All this is neat. But the ballyhooed walk- through sun, which is supposed to give the illusion of peering through gaseous layers, looks as quaint as a high school science project. STARS -- At the National Air and Space Museum indefinitely.