A Hawai'i telescope has photographed a new object larger than the planet Pluto at the fringe of our solar system, but astronomers can't agree on whether it's a planet.

Its discovery points out a gaping problem in astronomy — there's no widely accepted definition of a planet. And there's lots of disagreement. Here are three of the positions on the classification of the new object, known as 2003UB313:

"We think it should be a planet, because the International Astronomical Union decided to let Pluto retain its status as a planet, and this is Pluto-sized and it orbits the sun," said Chad Trujillo, a planetary astronomer at the Gemini Observatory on the Big Island, who discovered 2003UB313 with Mike Brown of Caltech and David Rabinowitz of Yale.

"It's exciting because it's big, but it doesn't really matter what you call it," said Dave Jewitt, a planetary astronomer with the University of Hawai'i's Institute for Astronomy.

"I think this is a Kuiper Belt object that happens to be very large. But we need to get a working definition (of a planet) real soon," said Institute for Astronomy planetary astronomer Karen Meech.

Meech serves on the subcommittee of the International Astronomical Union that is charged with defining a planet — the Working Group on Planetary System Nomenclature. Until the past couple of years, there wasn't any hurry because there were no new candidates for planethood.

Some folks argue that Pluto, the smallest and most distant planet in our solar system, only remains a planet out of respect for its history: It's been called one for so long and it would be confusing to suddenly change it status.

Now, that may not be enough.

Improving telescopes and improving computerized detection software are making big strides in identifying far-off objects in the solar system.

Last year, Trujillo's team announced finding the most distant known object in our solar system, an icy thing now known as Sedna. It's a little smaller than Pluto, but some folks were calling it the 10th planet, too. This year, two other distant objects a little smaller than Pluto have been located in the Kuiper Belt.

And the lack of a clear definition is becoming a problem of, well, astronomical proportions.

"The definition of a planet is remarkably fuzzy," said Fred Chaffee, director of the Keck Observatory on the Big Island.

As long as the newest objects were smaller than Pluto, it wasn't such a problem. 2003UB313 — while its exact size has not been calculated — is certainly as big as Pluto and may be considerably larger, though not as large as Mercury, Trujillo said.

Studies with the Gemini telescope indicated that its surface appears to very Pluto-like, with a lot of methane ice on its surface.

One of the things astronomers carefully study is the shape of an object's orbit. Most planets have orbits pretty near a circle. But Mercury's orbit is a little lop-sided, and Pluto's is even more so. At its nearest, Pluto is about 30 astronomical units from the sun, but at its most distant, it's nearly 50 astronomical units away. An astronomical unit is the distance from the sun to Earth.

New object 2003UB313 is even farther out, its orbit ranging from 38 to 98 astronomical units out.

Most planets also orbit within roughly the same plane, but Pluto's orbit is cocked 17 degrees, and 2003UB313 is 44 degrees out of kilter with the rest.

While some astronomers have been touting it as the new 10th planet, others say they're not even comfortable calling Pluto a planet.

Both objects are within the vast Kuiper Belt, which lies just beyond the orbit of Neptune and is believed to be the source of most comets that return every 200 years or less. Beyond even that is the theoretical Oort Cloud, which is believed to be the source of long-period comets — those that return every 200 or more years.

Jewitt said the Kuiper Belt is the hottest place for research in our solar system right now.

"It's where the leading edge is," he said.

He suggested that both Pluto and 2003UB313 are much more like Kuiper Belt objects than planets.

He is also uncomfortable with the idea of splitting objects unto tiny categories. There are three fundamental categories of bodies outside the sun, he said. The terrestrial zone includes the rocky planets of Mercury, Venus, Earth and Mars. The giant planets include the gas giants of Jupiter and Saturn and the ice giants of Uranus and Neptune. Anything beyond that, he said, is "the domain of the comets."

Jewitt said the issue of whether something in the comet zone is a planet or not is no issue at all.

"Who cares, anyway? It's completedly irrelevant. In terms of understanding the objects, it doesn't matter what you call it," he said.