Originally created 01/20/99

Pluto may be demoted



ALBUQUERQUE, N.M. -- Pluto's days as one of our solar system's nine major planets may be numbered.

Two groups within the International Astronomical Union are thinking about reclassifying the relatively puny planet -- either calling it a "minor planet" or lumping it in with an entirely new class of objects.

"For at least 20 years, it's been obvious that Pluto doesn't fit," said University of Maryland astronomer Mike A'Hearn, who heads the Planetary Systems Sciences Division of the International Astronomical Union.

With a diameter of only 1,440 miles, Pluto, the planet farthest from the sun, is smaller than the moon. And while other "major planets" have roughly circular orbits, Pluto carves out a sweeping ellipse that frequently takes it closer than Neptune, planet No. 8, to the sun.

A'Hearn wants to create a new class of objects for ice balls that orbit beyond Neptune and call them Trans-Neptunian Objects. Pluto would be Trans-Neptunian Object No. 1.

Brian Marsden of the International Astronomical Union's Minor Planet Center said he has a better idea: reclassify Pluto as a "minor planet," of which there are thousands, then make it take a number. The prized number 10,000 will probably come up next month.

"It's not a demotion," for Pluto to be referred to as the 10,000th minor planet, Marsden insisted. "It's an honor."

New Mexico astronomer Alan Hale, co-discoverer of Comet Hale-Bopp, suggested the debate is somewhat silly since there's really no clear definition of what a planet is. And, besides, "a hypothetical resident of Jupiter would probably laugh at our calling Earth a `major planet."'