GISBORNE CITY, New Zealand— The first sunrise of the new millennium will be a cold and lonely moment as the midnight sun dips below the horizon near Dibble Glacier in Antarctica and then, a few minutes later, creeps up again.

At the edge of the international date line, the silent Antarctic dawn will take place close to 14 hours before the big ball descends to mark the New Year in Times Square -- and about 21 hours before the sun rises in New York at 7:20 a.m. on Jan. 1, 2000.

But no one is likely to be there on that distant glacier to see the century's first dawn.

This has touched off a rough-and-tumble competition among the islands of the South Pacific for the claim of being the first inhabited place to witness the first fresh sunbeams of the future.

Fiji, Tonga, Kiribati and New Zealand's Pitt Island, near here (the astronomers' favorite), are the main contenders. In another part of the world, Katchall Island in the Indian Ocean is using a different theory of time to claim the first island sunrise. It has its scientific backers too.

Like the millennium itself, which purists point out does not begin for another year, the competition is a matter of definitions and technicalities. First midnight or first dawn? First permanently or temporarily inhabited place? Local time or Greenwich Mean Time?

And, particularly in the case of the often foggy Pitt Island, is there a sunrise if the weather is bad and nobody sees it?

''It's all just a matter of convention, but of course the whole business of the millennium is a matter of convention,'' said Dennis McCarthy, director of the Directorate of Time at the United States Naval Observatory in Washington. (''We are concerned with keeping the time for the country here,'' he said, explaining his job title. ''So as far as time is concerned, that is what we take care of.'')

''Why is the year 2000 the year 2000? It's just a convention established in the sixth century by Dionysius Exiguus,'' he went on, referring to the Christian theologian who is believed to have introduced the current system of numbering years. ''And I think it's pretty much assumed now that he got it wrong, if he actually was referencing the birth of Jesus.''

Right or wrong, things have gotten heated in this part of the world as New Year's Eve approaches -- a wild shifting of date lines, time zones and daylight saving times that has produced some strange geographical and temporal contortions.

Here in this easternmost city of New Zealand, yet another claim dominates: first city to greet the new century. Or to put it another way, first land mass to see the sunrise.

Looking more like a small town than a city, this quiet settlement of 30,000 seems a pleasant enough representative for the rest of us to greet the future. It is described repeatedly by residents as ''a nice place to raise children.''

''Many people in the outside world think we're isolated,'' said Mike Coyle, a member of the Gisborne District Council. ''We're glad. The younger people, they like to move away, have their excitement, then move back and enjoy their retirement. Or like me you can hop in the car any time, drive seven hours to Auckland, have a whale of a time and be back again on Monday.''

But like the designation of Jan. 1, 2000, as the start of the new millennium, all these South Pacific claims, by one key definition, are wrong.

They are based on local time rather than on Greenwich Mean Time -- or Coordinated Universal Time, as the scientists, if not the theologians, call it.

When the sun rises over the Pacific, it will still be about 3 p.m. on Dec. 31 in Greenwich, England, ground zero for the world's clocks. The new year, and the new century, will not yet have officially arrived.

''The only international standard for time across the world is Universal Time,'' said Robert Massey, an astronomer at the Royal Observatory at Greenwich. ''So our argument has always been that the new millennium will begin on Jan. 1 at the stroke of midnight along the Greenwich meridian.

''So the easiest way to measure who is first is to set your clocks to midnight G.M.T. and find out where the sun is rising. That in a sense is the first sunrise.''

At that moment, he said, the sun will be rising along a great arc running from eastern Russia through China, down along the border between Myanmar -- formerly Burma -- and Thailand, out into the Indian Ocean and on down to the Antarctic Circle.

Of all the spots on that particular arc, it is Katchall Island, India, part of the Andaman and Nicobar archipelago in the Bay of Bengal, that has decided to raise the cry of ''first.''

But by the time that happens, it will already be midday on Jan. 1 in the middle of the Pacific Ocean. Why wait?

Several places in the Pacific are making their own claims.

Pitt Island

The strongest claim appears to belong to Pitt Island, home to fewer than 60 farmers and their sheep. It is a part of New Zealand, but it lies in the blustery seas 500 miles off the coast -- and not much farther than that to the north of Antarctica.

Pitt, the more easterly of the two Chatham Islands, will greet the sunrise at 4:49 a.m. on Jan. 1, or 4:04 p.m. Greenwich Mean Time on Dec. 31. It will be 11:04 a.m. in New York.