Pluto vote 'hijacked' in revolt By Paul Rincon
Science reporter, BBC News
A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet. On Thursday, experts approved a definition of a planet that demoted Pluto to a lesser category of object.
But the lead scientist on Nasa's robotic mission to Pluto has lambasted the ruling, calling it "embarrassing".
And the chair of the committee set up to oversee agreement on a definition implied that the vote had effectively been "
hijacked".
(Hmmm... the Neptune conspiracy??) 
The vote took place at the International Astronomical Union's (IAU) 10-day General Assembly in Prague. The IAU has been the official naming body for astronomy since 1919.
Only 424 astronomers who remained in Prague for the last day of the meeting took part.
An initial proposal by the IAU to add three new planets to the Solar System - the asteroid Ceres, Pluto's moon Charon and the distant world known as 2003 UB313 - met with considerable opposition at the meeting. Days of heated debate followed during which four separate proposals were tabled.
Eventually, the scientists adopted historic guidelines that see Pluto relegated to a secondary category of "dwarf planets".
Drawing the line Dr Alan Stern, who leads the US space agency's New Horizons mission to Pluto and did not vote in Prague, told BBC News: "It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons.
"Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups'.
"Secondly, the actual definition is even worse, because it's inconsistent."
One of the three criteria for planethood states that a planet must have "cleared the neighbourhood around its orbit". The largest objects in the Solar System will either aggregate material in their path or fling it out of the way with a gravitational swipe.
Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune.
But Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path.
These rocks are all essentially chunks of rubble left over from the formation of the Solar System more than four billion years ago.
"If Neptune had cleared its zone, Pluto wouldn't be there," he added.
(Points for JSPB22!) 
Stern said like-minded astronomers had begun a petition to get Pluto reinstated. Car bumper stickers compelling motorists to "Honk if Pluto is still a planet" have gone on sale over the internet and e-mails circulating about the decision have been describing the IAU as the "Irrelevant Astronomical Union".
'Inconvenient arrangements' Owen Gingerich chaired the IAU's planet definition committee and helped draft an initial proposal raising the number of planets from nine to 12.
The Harvard professor emeritus blamed the outcome in large part on a "revolt" by dynamicists - astronomers who study the motion and gravitational effects of celestial objects.
"In our initial proposal we took the definition of a planet that the planetary geologists would like. The dynamicists felt terribly insulted that we had not consulted with them to get their views. Somehow, there were enough of them to raise a big hue and cry," Professor Gingerich said.
"Their revolt raised enough of a fuss to destroy the scientific integrity and subtlety of the [earlier] resolution."
He added: "There were 2,700 astronomers in Prague during that 10-day period. But only 10% of them voted this afternoon. Those who disagreed and were determined to block the other resolution showed up in larger numbers than those who felt 'oh well, this is just one of those things the IAU is working on'."
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