Tama Starr thrives on seeing 300,000 people swarm New York's Times Square to brave the cold, watch an illuminated apple descend a pole and mark a new year.

"Every single year people gather in the crossroads of the world, because the sacred is intersecting the mundane," says Starr, vice president of Artkraft Strauss Sign Corp., the company that annually choreographs the apple's descent.

But as this year's crowd waits for the apple to hit bottom, they'll have more time to celebrate the sacred and the mundane on New Year's Eve. The Naval Observatory has announced the addition of a leap second at year's end.

Starr plans to make use of that spare second, filling the gap with a one-second light show. To make it appear sparkling, she'll put a strobe inside the apple.

Leap seconds become necessary when the Earth's spin fluctuates. Dennis McCarthy, an astronomer at the Naval Observatory, says the leap second will be in place at midnight Greenwich Mean Time (now called Universal Time). In other words, the second will be inserted at 11:59:59 p.m. GMT, just as Washington adds it at 6:59:59 p.m. EST.

So things don't get too confused, Tama Starr plans to add it as the apple lowers over Times Square.

Beside's New Year's Eve, December is full of celestial happenings:

Comet Bradfield remains a binocular object through the month, though it's not as spectacular as it was in the middle of November. Look for the comet just south of due west, high in the early evening sky. Bradfield will be competing with the full moon at the end of this week, but as the moon wanes next week, the comet will become more visible.

The planet Jupiter could qualify as this year's Christmas Star. It's that bright object high in the east. Jupiter will swing around the southern sky, setting in the west. Staying low in the west, Venus will grow more confident in the coming months.

Mir, the Soviet space station, swings briefly into Washington's view on the evening of Saturday, Dec. 12. Although it looks like a swift airplane, it won't have the blinking lights.

Viewers may want to face the southwest at 5:28 p.m., says Dr. William Howard of the Naval Space Command. Mir will reach it's maximum height at 5:33 p.m., when it's in the southeast. By 5:40, the space station will have "set" in the east-northeast.

Winter arrives Dec. 22. From Earth, it appears as if the sun is reaching the lowest point in the sky. The Winter Solstice at 4:46 a.m. EST ushers in three months of winter and from then on the days start getting longer.

If you're looking to stuff the stocking of a sky buff, the gift shop at the National Air & Space Museum has a few ideas. The Stargazer's Bible by W. S. Kals ($6.95) offers novice astronomers an introduction to the night sky and a primer on gadgets for watching cosmic phenomena. Colin Ronan's The Skywatcher's Handbook ($13.95) is designed for a more sophisticated amateur, showing what celestial mechanics are all about.

Sky wheels (planispheres) show all the major constellations of the night sky, and sell for $5.50-$10 at the museum's upper-level gift shop. These are handy for peeking around the sky and picking out the stars.

Bounce the universe off a friend with an Inflatable Celestial Globe ($13.50). Or build a galactic monopoly with Solarquest, the space-age real estate game ($18).

Events for the Mind

Dec. 5 -- Last February's supernova keeps astronomers talking. David Devorkin discusses the astronomical event of the year. Einstein Planetarium, Air & Space Museum. 9:30 a.m. Free.

Dec. 5 -- Dr. Thomas Matthews, an astronomer from the University of Maryland, explains galaxies and why they run in packs, when he talks about "Galaxies and Clusters." At the university's observatory lecture hall at 8 p.m. View the sky after the lecture. Free. For further information, 454-3001.

Dec. 10 -- Carl Sagan provides a first-hand account on the historic Mariner mission in his lecture, "The Voyage to Venus." Tickets are free, but limited to four per person. They are available at the Langley Theater, Air & Space Museum, beginning at 5 p.m. The lecture starts at 8 p.m.

Dec. 11 -- Meet a panel of the space scientists and administrators who assembled the Mariner 2 mission to Venus. 2-4 p.m. Einstein Planetarium. Free.

Dec. 12 -- Dr. Joseph Boyce, a NASA scientist, says Mars most likely will be the next planet visited by us. Join him at 9:30 a.m. for his lecture, "Exploring the Planet Mars." Einstein Planetarium. Free.

Dec. 20 -- Dr. Patrick Harrington of the University of Maryland explains how ancient cultures treated the winter solstice in his lecture, "Sun Gods and Prehistoric Europe." Sky viewing after the 8 p.m. lecture. The lecture hall at the university's observatory. Free. For further information, call 454-3001.

Dec. 27. For those fortunate enough to get new telescopes as gifts, the Goddard Visitor's Center in Greenbelt is offering a free workshop on telescopes starting at 1 p.m. 286-8981.