Why is pluto no longer a planet?

Why did they take pluto off as a planet?

It was considered too small...they call it a dwarf planet now

They decided it was way too small...

no- you see Haily's comet ran into Pluto which has now made what can be considered a super planet.
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no- you see Haily's comet ran into Pluto which has now made what can be considered a super planet.
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Because if you include Pluto as a planet, by any reasonable definition, you have to include a bunch of other (previously unnamed) pieces of rock, too.

seriously though, isn't that the stupidest sh*t you've ever heard of. the science commity just wanted to make the headlines for a little bit. it might not qualify for them, but I'll alway's consider it a planet

there were so many other things out there bigger than pluto. I agree with piker187 though, its so stupid. pluto will always be a planet to me and I dont think they should be able to go around randomly changing that.

Not big enough. Xena is bigger than Pluto and wasn't classed as a planet. I think it has a lot to do with the orbit of the sun and how much pull it has and stuff as well
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pluto was very far away! pluto got destroyed because it was soo cold or a comety probably hit the poo planet!!!

Pluto is still a planet to many astronomers. The IAU vote to demote Pluto was made by a tiny minority of its members, most of whom are not planetary scientists. Dynamicists, astronomers who study orbital dynamics, hijacked the IAU vote by railroading through a proposal on the last day of a two-week conference when most attendees had already gone home. No absentee voting was allowed. This was a political, not a scientific decision. Dynamicists seek to classify objects solely by where they are while ignoring what they are. In contrast, planetary scientists recognize that even if an object does not dominate its orbit, if that object has enough self gravity to pull itself into a round shape (a condition known as hydrostatic equilibrium), that object has the same geological processes as the classical planets we know. Pluto, Ceres, Eris, and MakeMake, by this definition, are planets, not asteroids. The IAU needs to correct the linguistic nonsense in its definition, which states that dwarf planets are not planets at all. They are. They simply are one subcategory of the broad class of objects that fall under the umbrella of the term "planet."

laurele: There's no one "right" definition of planet. How we define it is a matter of consensus, and if we include Pluto as a planet, as you point out, we have to include a bunch of other previously unknown lumps of rock. That may not be a bad thing, but they definition had to be straightened out one way or the other, and they chose to settle it by excluding pluto, rather than including the others.

But in spite of the IAU vote by four percent of its members, most of whom are not planetary scientists, there is no consensus among astronomers in favor of this definition. That is because this definition didn't straighten anything out; its sloppiness and vagueness only made the planet definition issue more confusing. Therefore, it was a step in the wrong direction. The small group who made this choice need to recognize that this issue is not settled and include input from the many planetary scientists who are not even part of the IAU but nevertheless focus all their research on studying planets. A first step towards that was the Great Planet Debate this August in Laurel, MD.