Planet Status Up For Debate Once Again

It seems that in today's troubled times, not even the planets can be counted on for stability... as over 2,500 astronomers are presently meeting in Prague to come to a universal definition of what qualifies as a planet. And that could spell trouble for the smallest "planet" in Earth's solar system, Pluto.

"So far it looks like a stalemate," one of those scientists, Pavel Suchan, told CNN. "One half wants Pluto to remain a planet, the other half says Pluto is not worth being called a planet."

At issue is Pluto's small size, relative to the other eight planets orbiting the Sun. Pluto's planetary status has been debated for years, almost from the moment it was discovered by Clyde Tombaugh in 1930 -- but the 12-day meeting of the International Astronomical Union currently underway hopes to set a universal standard to determine what can be called a planet, and what is merely an oversized asteroid.

That won't be as easy as it may sound, however... as there is no standard criteria in place among astronomers to determine what qualifies as a planet. Should planets be defined by their location, for example, or by their size? If it's the latter... what should that size be? And should that size be bigger, or smaller, than Pluto?

Which, in turn, creates yet another interesting dilemma. If scientists decide that size should determine a celestial body's planetary status -- and if such bodies smaller than Pluto meet the definition -- then we could see Earth's solar system "expand" to as many as 53 new planets. Under that standard, even Earth's moon would then be a "planet," as it is larger than Pluto.

Other classification systems under consideration would group planets by composition -- similar to how stars and galaxies are already designated.

For now, there are at least two planetary bodies that could be affected by the astronomers' findings: Pluto, and a bright, rocky object first detected in 2003 that is roughly 70 miles wider in diameter than Pluto. Like the smallest planet, this body -- called "Xena" by its discoverer, Michael Brown -- is located in the distant Kuiper Belt beyond Neptune.

Xena is currently the farthest known object in the solar system, at more than 9 billion miles from the sun.

FMI: www.iau.org