Astronomers Say Pluto Is Not A Planet.

[ValleyOfDecision]

Astronomers say Pluto is not a planet

7 minutes ago

Leading astronomers declared Thursday that Pluto is no longer a planet under historic new guidelines that downsize the solar system from nine planets to eight.

After a tumultuous week of clashing over the essence of the cosmos, the International Astronomical Union stripped Pluto of the planetary status it has held since its discovery in 1930. The new definition of what is — and isn't — a planet fills a centuries-old black hole for scientists who have labored since Copernicus without one.

Although astronomers applauded after the vote, Jocelyn Bell Burnell — a specialist in neutron stars from Northern Ireland who oversaw the proceedings — urged those who might be "quite disappointed" to look on the bright side.

"It could be argued that we are creating an umbrella called 'planet' under which the dwarf planets exist," she said, drawing laughter by waving a stuffed Pluto of Walt Disney fame beneath a real umbrella.

The decision by the prestigious international group spells out the basic tests that celestial objects will have to meet before they can be considered for admission to the elite cosmic club.

For now, membership will be restricted to the eight "classical" planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Much-maligned Pluto doesn't make the grade under the new rules for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit."

Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.

Instead, it will be reclassified in a new category of "dwarf planets," similar to what long have been termed "minor planets." The definition also lays out a third class of lesser objects that orbit the sun — "small solar system bodies," a term that will apply to numerous asteroids, comets and other natural satellites.

It was unclear how Pluto's demotion might affect the mission of NASA's New Horizons spacecraft, which earlier this year began a 9 1/2-year journey to the oddball object to unearth more of its secrets.

The decision at a conference of 2,500 astronomers from 75 countries was a dramatic shift from just a week ago, when the group's leaders floated a proposal that would have reaffirmed Pluto's planetary status and made planets of its largest moon and two other objects.

That plan proved highly unpopular, splitting astronomers into factions and triggering days of sometimes combative debate that led to Pluto's undoing.

Now, two of the objects that at one point were cruising toward possible full-fledged planethood will join Pluto as dwarfs: the asteroid Ceres, which was a planet in the 1800s before it got demoted, and 2003 UB313, an icy object slightly larger than Pluto whose discoverer, Michael Brown of the California Institute of Technology, has nicknamed "Xena."

Charon, the largest of Pluto's three moons, is no longer under consideration for any special designation.

Brown was pleased by the decision. He had argued that Pluto and similar bodies didn't deserve planet status, saying that would "take the magic out of the solar system."

"UB313 is the largest dwarf planet. That's kind of cool," he said.

Copyright © 2006 The Associated Press. All rights reserved. The information contained in the AP News report may not be published, broadcast, rewritten or redistributed without the prior written authority of The Associated Press.

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[superfrogsavesdcisback]

Hmmm, I wonder what my very educated mother would say about this. There's no more pizza. :P

I know the textbook publishers might be miffed about having to change the information with school starting almost everywhere now.

[carboncopysue]

:rolleyes: that's just not right, for them to make up rules like that...

They made a huge decision like that and didn't even have the majority of the members present? (400-something people voted out of 1000+ scientists that attended the conference)

Sue.

[Aje_Templar]

To heck with them. I say Pluto and Quaoar are planets.

[deecoily]

Now that's sad

Publishers of science text books are rubbing their hands together and planning their luxury vacations right about now...