HOT TIPS : COUNTDOWN TO MILLENNIUM, ONE FACT-FILLED DAY AT A TIME.

Byline: Daily News Wire Services

The end is coming!

As of today, in fact, it is only 539 days away, or 905, depending upon whether you think the 20th century ends on Dec. 31, 1999, or Dec. 31, 2000.

If you don't want to work out the calculations yourself, they're all done for you in the 21st-Century Countdown Calendar ($11.95, Countdown Enterprises, P.O. Box 1946, La Jolla, Calif. 92038-1946).

The 1998 calendar not only offers a day-by-day countdown to the millennium, but also a series of 365 daily ``brief reflections on the beginnings of things,'' each color-coded (purple for cosmology, red for literature, green for biology).

Part II, which will continue the countdown through 1999, covers human history, and Part III, for the year 2000, will summarize events in the 20th century.

In this year's Countdown Calendar, for example, the June 1 entry informs us that 255 million years ago, some kind of worldwide cataclysm wiped out 95 percent of all species of marine life, ``the worst extinction in history ...''

A sobering thought while waiting for the end.

Royal revival: In ancient Greece, purple dye was so precious that mere mortals weren't allowed to set foot on purple carpets rolled out for the gods. In the Roman Empire, purple togas worn by the Caesars signaled that they personified the divine.

Today, purple is back on the scene, but it's not reserved strictly for those holier than thou. Expressions, a major custom-upholstery company, has seen purple take off since it first dabbled in it three years ago.

``As Generation X hits 30, they're interested in having more color than their parents did,'' Expressions spokesman Cecil Adams said. ``Not everyone wants to be at Grandma's house.''

Dan River, a leading maker of bed linens, uses a wide range of purple in its Colours by Alexander Julian collection.

Lisa Newsom of Veranda magazine put a large bouquet of purple pansies, anemones and delphiniums on the cover of a recent issue. ``I chose purple,'' she says, ``because it is a bellwether color that is gaining major acceptance in design.''

Pest patrol: Protect your plants from animals and birds with the Scarecrow With a Brain.

Just attach it to a regular garden hose. When a bird or animal approaches, a motion-activated sensor is set off triggering the sprinkler mechanism powered by two 9-volt batteries. A spray of water is activated for three seconds, then abates for seven seconds. If the animal or bird returns, it activates again.

The device comes with an 18-inch stake but may be mounted also. The Scarecrow has a suggested retail price of $129. For more information or to find stores that sell it, call [phone].

Who wears short shorts? Sixty years ago, when Alice Marble stepped onto the court at Wimbledon wearing shorts, it was a scandalous thing to do. It took nerve and a sense of the dramatic.

Today, the Spice Girls are headline news in their short shorts. And it still takes some nerve and a good figure to wiggle into a pair.

This year's crop includes tight shorts threaded with spandex to hug well-toned bodies perfectly. Looser styles, in cottons, have drawstring waists.

Best tops are tubes, tanks and camisoles. For a leggier look, try platform sandals or thick-soled sneakers. Or go flat with ballet styles or slides.