Okay, okay -- so Halley's speeding comet of gas and ice won't hurtle by the earth until 1986. There's still plenty to see in the evening sky this summer, and a night tour of the U.S. Naval Observatory is just the place to begin looking.

This Friday night, and again Monday and Tuesday, it will give you views of Saturn and Jupiter, a close-up of the moon and perhaps a glimpse of starlight that started its journey to earth around 455 A.D., shortly after the Vandals sacked Rome. If you can't make it then, there'll be other night tours July 18-20 and August 15-17.

The observatory is located at Massachusetts Avenue and 34th Street NW, atop some of the highest and -- so it seems -- most poorly lit ground in Washington. But the minimal lighting makes for better telescope observation and helps prepare you for your journey across the universe -- as the noise of traffic gives way to the quiet darkness of the star-flecked sky.

The ascent to the stars includes a lift on the 24-ton observation platform, which, at the touch of a button, rises slowly toward the white dome and the 32-foot-long white- enamel telescope trained like a cannon on its distant targets.

On a recent tour, that ride on the creaking floor brought a flurry of nervous laughter and conversation among the adults and kids -- seated in an arc of folding chairs at platform's edge -- as they waited to be shown a place where stars are born: the Great Nebula in the constellation of Orion.

In anticipation, I conjured up images of what this powerful telescope would reveal: swirling, superheated gases, alternately sucking in and spewing out bits of the cosmos that would eventually become stars. My turn at the telescope came, and my eyes were filled with another world of tiny, wavering points of light, but I saw no whirling gases, no cosmic violence. Still, the drama and power were undeniable: The nebula is 1,500 light years away and I was gazing on light emitted shortly after the fall of Rome.

Much closer to home, through another of the observatory's telescopes, we peered at a satellite the Ancients believed to be a reflection of earth -- the moon. The Apollo spacemen have walked on it -- even driven a golf ball there -- but the mystery remains. People stood before the telescope, one eye squinting, a point of condensed blue light playing on a cheekbone; jaws went slack with surprise as the grainy, cratered surface was revealed.

While most adults were content with brief peeks through the telescopes, the prospect of space missions, galaxies and double stars seemed especially to capture the imagination of children. One youth in particular, an 11-year-old Fairfax boy who hopes to be an astronaut, was a fountain of questions about Jupiter's whirlpool and the Viking spaceship going around Mars.

During the night tours, you ca also browse in the Victorian-style lobby with its heavy oak doors and marble staircase, wandering among the antique astronomical instruments and display cases that lay out the 150-year history of the observatory.

For more sophisticated observers, the observatory offers day tours of a much more technical nature, with an emphasis on its mission and current programs.

The tours, in fact, are only a small portion of the observatory's work. Among other things, its scientists monitor a series of 30 atomic clocks that keep time accurate to within billionths of a second. And they determine the precise locations of stars and planets to provide the necessary groundwork for other astronomical projects in observatories across the nation. TOURING THE OBSERVATORY -- It can accommodate a total of 140 people each tour night. Groups of more than 15 are asked to make reservations at least two months in advance. The day tours are not considered appropriate for children. For information, call 653-1543. SIGHTS AT ANOTHER SITE UNIVERSITY OF MARYLAND -- Its department of astronomy stages an open house at 8 p.m. on the 5th and 20th of each month. A graduate student or professor explains the celestial phenomena for that evening. Telescope observations follow. Groups of 10 or more should make reservations. Call the university's astronomy department at 454-3001 for more information..