If you want to precisely count down to the year 2000, visit the U.S. Naval Observatory's Web site. The observatory uses its Master Clock, an atomic clock, to calibrate the countdown. The site also features a countdown to the "official" millennium -- Jan. 1, 2001. To reach both, go to the homepage, www.usno.navy.mil, then link to the countdowns via the site's millennium pages.

Public response to the official date has been supportive, says astronomer Alan Fey, who developed the Web pages along with others at the observatory. "Generally, the public is happy that we're pointing out that the millennium really starts on Jan. 1, 2001, because it's right," he says.

On the Countdown to the Year 2000 page, which features a clock superimposed on a photograph of the observatory's main building, you will see the time displayed in Universal Time, once known as Greenwich Mean Time. Since we will be in Eastern Daylight Time until 2 a.m. on Oct. 31, the time currently on the Web site is four hours ahead. After the change to standard time, the countdown clock will be five hours ahead.

After enjoying leaves of crayon yellow and blazing red during these autumnal days, scout the night skies for colorful planets:

Just before the sun rises -- and resting near the front leg of the constellation Leo -- the planet Venus will be high in the east-southeast. It's too bright to miss, as the ever-effervescent Venus appears to glow at a strong negative fourth magnitude.

Find the dim Mars skimming through the middle of the Milky Way stream, low in the south-southwest, after sunset.

Very bright, Jupiter rises about an hour after sunset now, traveling with the constellation Pisces. Saturn follows about 40 minutes later as they cruise across the southern sky. Jupiter now crosses the meridian a little after 2 a.m., crossing it progressively earlier as the month continues.

Down-to-Earth Events

Oct. 5 (Tonight) -- Astronomer Patrick Harrington discusses "Observing Planetary Nebulae With HST" at the University of Maryland astronomy department's open house. After the lecture, gaze at the sky through the telescope at the university's observatory. On Metzerott Road, across from the System Administration building. 9 p.m. Information, 301-405-3001; Web, www.astro.umd.edu/openhouse.

Oct. 9 -- The wonders of the real universe present themselves at "Star Watch" at the Goddard Space Flight Visitor Center in Greenbelt. You may bring your own telescopes and binoculars, or use equipment at the visitor center, 7-9 p.m. Information, 301-286-8981.

Oct. 9 -- Join the National Park Service and the National Capital Astronomers as they explore the night sky at the field across from the Rock Creek Nature Center, at Military and Glover roads NW. 7:30 p.m. Information, 202-426-6829; Web, www.nps.gov/ rocr/planetarium.

Oct. 10 -- The Northern Virginia Astronomy Club presents a talk on ancient astronomy. The group meets at Lecture Hall 1 on the campus of George Mason University in Fairfax. 6 p.m. Free parking in lots F and G; Web, astro.gmu.edu/%7Enovac/index.html.

Oct. 16 -- Star Party and Telescope Meet 1999, sponsored by the Northern Virginia Astronomy Club at C.M. Crockett Park, near Warrenton. 3 p.m.-11 p.m. In the afternoon learn to recognize constellations, buy or make telescopes and take pictures of the night heavens. In the evening, tour the cosmos with club members. Free, though there is a $5/car park entry fee. The club expects to have a sign-language interpreter for the afternoon talks and evening sky tours.

Directions: West on I-66 to Exit 43-A at Gainesville to Route 29 South toward Warrenton. After 11.8 miles on Route 29, stay left (toward Culpeper), to bypass Warrenton. (You will still be on Route 29 South.) Go 1 mile to the Route 643 exit, Meetze Road. At top of exit ramp, turn left on Route 643 East. Go 7.5 miles on Route 643. Watch for small C.M. Crockett Park sign on your left. Turn onto the park entrance road, proceed a half-mile to park entrance.

Oct. 16 -- The Montgomery College Planetarium presents the lecture, "How Stars Are Born." The planetarium is located on Fenton Street, Takoma Park. Parking is available in the faculty lot. 7 p.m. Information, 301-650-1463; Web, myhouse.com/ mc/planet.htm.

Oct. 20 -- Astronomer Patrick Leventhal discusses "Discovery of Anti-Particles at the Center of our Milky Way Galaxy" at the University of Maryland astronomy department's open house. Sky-gazing after the lecture.

Oct. 27 -- Find out about the renowned Saturn V launch vehicle that propelled astronauts to the moon. Gather with curator Mike Neufield at the Gold Seal, Milestones of Flight Gallery, National Air and Space Museum. Noon. Information, 202-357-2700.

Oct. 30 -- Does extraterrestrial life exist? Join Stephen J. Dick of the U.S. Naval Observatory for a colorful, galactic tour of the controversy. 6 p.m. at the Albert Einstein Planetarium in the National Air and Space Museum.