THE STORY...

Astronomers find space for three new planets

Astronomers are proposing a galactic shift of our solar system that could raise the number of planets from nine to 12 and open the way to naming dozens more.

After two years of debate, a draft resolution will be formally presented to the International Astronomical Union at a convention in Prague on Wednesday with the aim of settling once and for all what defines a planet.

For now, it appears there will be cosmic consensus and Pluto's solar system status is safe.

But the proposal could change.

Nearly 2,500 astronomers from 75 nations meeting in the Czech Republic capital to hammer out a universal definition of a planet will hold two brainstorming sessions before they vote on the resolution next week.

Still, it's likely the resolution will pass and Pluto won't be booted out from its planetary posse.

The draft is coming from the IAU's executive committee, which only submits recommendations likely to get two-thirds approval from the group.

IAU President Ronald D. Ekers said the draft definition was an attempt to end decades of debate.

"We don't want an American version, a European version and a Japanese version" of what constitutes a planet, he said.

Besides reaffirming the solar system status of Pluto, the IAU draft resolution recognizes 2003 UB313, the farthest-known object in the solar system; Pluto's largest moon, Charon; and the asteroid Ceres, which was a planet in the 1800s before it got demoted.

The IAU panel also proposed a new category of planets called "plutons," referring to Pluto-like objects found in the Kuiper Belt, a disc-shaped zone where thousands of comets and planetary objects float beyond Neptune.

Pluto and two of the newcomers, Charon and 2003 UB313, would be defined as plutons.

If the resolution is approved, the 12 planets in our solar system listed in order of their proximity to the sun would be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon, and the temporarily named 2003 UB313.

Michael Brown of the California Institute of Technology, who discovered the celestial object UB 313, nicknamed it Xena after the saucy warrior princess in a television series.

But the panel said it would likely be renamed under another moniker. The name Persephone is said to be a leading contender.

Even if the family of planets grows when astronomers vote on Aug. 24, the universe is likely to continue expanding.

"The snag is, of course, that the moment we say there are going to be three, four, five more planets in the solar system -- how are we going to deal with the objects that might be that size, even further out?" York University astronomer Paul Delaney wondered.

"The Kuiper Belt -- which is this trans-Neptunian area in our solar system -- is populated probably by tens of thousands of objects," he said, appearing on CTV's Canada AM.

The IAU has a "watchlist" of at least a dozen other contenders that could receive planetary promotions once more is known about their sizes and orbits.

"The solar system is a middle-aged star, and like all middle-aged things, its waistline is expanding," Jack Horkheimer, director of the Miami Space Transit Planetarium in the United States and host of Public Broadcasting's Stargazer television show, told The Associated Press.

Pluto's critics, who argue the planet is too tiny, might still enter the ring for a fight.

Experts have been split over whether Pluto should remain a planet, as it is the smallest of the current nine planets and farthest from the sun.

The debate about Pluto's status as a planet has been ongoing for decades after the planet was found to be only one four-hundredths of the mass of Earth.

When it was confirmed in the 1990s that the Kuiper Belt was sprinkled with numerous bodies similar to Pluto, some scientists voiced their doubts about its status.

Under the IAU proposal, however, Pluto meets its proposed new definition of a planet -- it is a round object larger than 800 kilometres in diameter that orbits the sun and has a gravitational pull strong enough to pull itself into a spherical shape.

"People were probably wondering: If they take away Pluto, is Rhode Island next?" Binzel quipped. "There are as many opinions about Pluto as there are astronomers. But Pluto has gravity on its side. By the physics of our proposed definition, Pluto makes it by a long shot."

Intresting story? yes.
Developing story? not so much, pretty much said and done.

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