Why was Pluto demoted from a planet to dwarf planet?

The short answer is that there are many other similar dwarf planets at the edge of our solar system. Allowing Pluto to remain known as a planet, would mean re-defining the definition of planet, and adding several more planets to our solar system. Classing Pluto as it really is, instead of what it was once thought to be, is more scientifically correct.

While I respect the sentiments of many that Pluto should be granfathered in as a planet as honorable and noble, it would not be scientifically correct.

Cheers :-)

Hi. The problem that scientists had to deal with is that our ability to detect faint objects has improved to the point where we see many more things that we could not see before. If they did not define a planet more rigidly then a lot of new "planets" would be discovered each year. If they find an object the meets the new planetary criteria then there will be another planet. Until now they have not.

OMG! i just learned this.

it was demoted because if pluto was actually a planet, than 100,000 other planets in the Kuiper Belt would also be planets, because they're the same size as Pluto!

Lots of information on this on wikipedia, space.com, and astronomy.com.

Basically Pluto met 2 of the 3 criteria that are now required (as of Aug 24, 2006) for an object to be labelled a planet.

you're treading on dangerous ground my friend.

all those other answers were sound and vaild. as far as they go. I'll tell you the real deal. don't tell anyone else.

Pluto got heavy into blackjack and craps with jupiter and neptune.

he racked up bills no honest man or planet could pay.

the only thing left was his status as a planet.

It broke his heart but at least they didn't break his knees.

the two loan shark planets are selling pluto's planet-hood as we speak on ebay. I'm lurking and hope to snap it up at 10-18 billion, with 8 seconds left on the clock.

don't tell anyone I told you.

you know how planets are.

peace out demotion questonier dude.

becasue in this day and age with all the newest and latest technologies it is too small to be considered a planet and if they were to contiue to call it a planet they would also have to call others floating around it planets as well

Cuz it's smaller than most moons: so it's been bumped off the solar systems charts, and declared a meaningless piece of space rock that got trapped in our sun's orbit.

because the planet pluto decreased itself by size and became more of a asteriod, lol.

Also because the IAU and dumb.

because Nasa thought it was too small. :-( poor planet. i am really small and i am allowed in this world!! i think Pluto should still be a planet.

NASA wanted to downsize the solar system.