It looks like a golden martini olive impaled on a silver toothpick. As the trees lose their leaves around the vice president's place, you may catch a glimpse of it atop the U.S. Naval Observatory.

It's a brand new "time ball," and the best way to know the precise instant the year 2000 arrives will be to see it drop.

Better than watching Dick Clark count down to the new year as the ball descends in Times Square?

Absolutely.

The Naval Observatory on Massachusetts Avenue NW is where the nation's atomic chronometer quietly parses eternity down to the billionth of a second. It doesn't look like a clock, actually, but rather an amazing stereo system, with rows of switches and dials and one red light, endlessly blinking out the Official Second.

One.

Two.

Three.

So on the observatory's roof, at 12:00:00 a.m., Washington's ball will drop with peerless precision.

To make things interesting, and to symbolize global time, instead of simply running an orange extension cord from the hydrogen maser "master clock" up to the ball, one of the observatory's time technicians on the roof will determine midnight from a portable Global Positioning System receiver, then drop the ball.

It's all the same, because the 24 Air Force GPS satellites set their watches by the observatory's atomic clock.

Washington will be a link in an earth-encircling chain of time-ball drops to mark the beginning of the new year as it sweeps westward from the international date line, with balls dropping at observatories on five continents. The Naval Observatory plans to distribute 2,000 free tickets to watch from the excellent vantage point of the lawn near Vice President Gore's helipad. The vice presidential residence shares the compound with the observatory.

There will be an announcement soon on how to order tickets, and a countdown clock will be erected next week outside the observatory's main entrance on Massachusetts Avenue. But even without a ticket, people near the observatory can catch a glimpse of the big moment: A powerful spotlight will shine on the gold-painted aluminum ball, which is four feet in diameter, and more people will be able to see the accompanying fireworks.

But don't expect anything like the slowly sinking sphere of Times Square. It turns out people have been dropping time balls even longer than TV celebrities have been leading Times Square crowds in singing "Auld Lang Syne," and the observatory intends to be historically accurate.

At 10 minutes to midnight, the ball will be hoisted part-way up the 35-foot aluminum pole. With five minutes to go, it will be raised to the top. At midnight, a federal time keeper will release the gear that holds the ball in place, and it will fall fast, driven by gravity.

"The first motion of the ball," just as it begins to fall, will signal the new year, says Steven J. Dick, historian at the observatory.

In contrast, to build suspense, the Times Square ball descends gradually as the crowd counts down, and the new year rings in when the ball reaches the bottom.

The observatory's method dates to the first time-ball drop in Portsmouth, England, in 1829. Time balls fed the world's growing need for exactitude. Astronomers could tell time precisely from the stars, and dropping a ball from a poll was how they informed the public, according to Dick.

In 1844, then-Secretary of the Navy John Y. Mason instructed the observatory to devise a signal so that "time may be made known every day to the inhabitants of the City of Washington."

Starting the next year, every day at noon a ball was dropped at the observatory, then at 23rd and E streets NW. Residents could set their pocket watches, and seafarers could calibrate their chronometers, which had to be accurate to determine longitude.

The daily time-ball drop was relocated in 1885 to what is now the Old Executive Office Building next to the White House until the tradition ended in 1936.

"Ball time" became a popular synonym for "correct time."

New technologies were developed to disseminate time. A regular New York City time-ball drop was inaugurated in 1877, using a telegraph alert from the observatory--with the signal delayed 12 minutes to allow for the time difference between New York and Washington in those pre-time-zone days. For years, Western Union sold office clocks that automatically corrected themselves based on a daily signal from the observatory. In Washington, the observatory sent telegraph signals to city fire stations to ring their bells at 7 a.m., noon and 7 p.m.

Soon came radio time alerts, followed by telephone updates. Call 202-762-1401, and a mechanical voice will tell you what time the atomic clock says it is.

And finally, GPS: the mother of all time balls.

While we're on the subject, the observatory's masters of time seem equipped to settle a related question: When the ball drops, it will signal merely the year 2000, they say. The ball will be dropped again a year later. Only then will we enter a new millennium.

CAPTION: Steven J. Dick, historian at the U.S. Naval Observatory in Northwest Washington, looks up at the time ball from the observatory's roof.