My daughters are not too happy about this:

Pluto, beloved by some as a cosmic underdog but scorned by astronomers who considered it too dinky and distant, was unceremoniously stripped of its status as a planet Thursday.
The International Astronomical Union, dramatically reversing course just a week after floating the idea of reaffirming Pluto’s planethood and adding three new planets to Earth’s neighborhood, downgraded the ninth rock from the sun in historic new galactic guidelines.
The shift will have the world’s teachers scrambling to alter lesson plans just as schools open for the fall term.
“It will all take some explanation, but it is really just a reclassification and I can’t see that it will cause any problems,” said Neil Crumpton, who teaches science at a high school north of London. “Science is an evolving subject and always will be.”
[…]
“The word ‘planet’ and the idea of planets can be emotional because they’re something we learn as children,” said Richard Binzel, a professor of planetary science at the Massachusetts Institute of Technology, who helped hammer out the new definition.
“This is really all about science, which is all about getting new facts,” he said. “Science has marched on. … Many more Plutos wait to be discovered.”
Pluto, a planet since 1930, got the boot because it didn’t meet the new rules, which say a planet not only must orbit the sun and be large enough to assume a nearly round shape, but must “clear the neighborhood around its orbit.” That disqualifies Pluto, whose oblong orbit overlaps Neptune’s, downsizing the solar system to eight planets from the traditional nine.

My daughters rejected this and refused to accept that Pluto isn’t a planet. I think they are emotionally attached to it 🙂 They will be happy to know they are not alone:

But mission head Alan Stern said he was “embarrassed” by Pluto’s undoing and predicted that Thursday’s vote would not end the debate. Although 2,500 astronomers from 75 nations attended the conference, only about 300 showed up to vote.
“It’s a sloppy definition. It’s bad science,” he said. “It ain’t over.”