why pluto is discarded from 9 planets?

Question

just for reference

Answer 1

its is not a planet any more because sientist say it is skrinking or getting smaller.

its is now considered as a dwarf planet

Answer 2

Pluto, the last planet to join the heavenly pantheon, became the first to leave it. The status of Pluto had been under discussion for some time, but with the discovery of 2003 UB313, nicknamed Xena, the question became acute, for it seemingly had as much right as Pluto to be called a planet.

On August 24, 2006, the International Astronomical Union surprised the world by voting in a new definition of planet, one that would exclude Pluto and bring the total number down to eight. (There had previously been been strong speculation that the redefinition would bring the total up to 12 instead of down.)

Pluto was instead classified as a dwarf planet, along with Ceres and the aforementioned Xena. The main difference between a dwarf planet and the real thing is that the dwarf variety has not cleared the area of its orbital path.

This redefinition met with a wave of protests from those who wanted to see the ninth planet grandfathered in, including but not limited to supporters of the late Clyde Tombaugh, who discovered Pluto in 1930. His widow, however, said he would have been accepting of the IAU's decision since "he was a scientist" and understood that astronomers had to take into account newly discovered objects in the Kuiper Belt (where Pluto is located).

Answer 3

Once known as the smallest, coldest, and most distant planet from the Sun, Pluto has a dual identity, not to mention being enshrouded in controversy since its discovery in 1930. On August 24, 2006, the International Astronomical Union (IAU) formally downgraded Pluto from an official planet to a dwarf planet. According to the new rules a planet meets three criteria: it must orbit the Sun, it must be big enough for gravity to squash it into a round ball, and it must have cleared other things out of the way in its orbital neighborhood. The latter measure knocks out Pluto and 2003UB313 (Eris), which orbit among the icy wrecks of the Kuiper Belt, and Ceres, which is in the asteroid belt.

Answer 4

The honest answer is that Pluto does not "clear its own orbit". Its orbit is a little different from the other planet and it actually crosses the orbit of Neptune, so for 20 years (1979-1999) Pluto actually wasn't the closet planet.

The Internation's Astronomers Union came up with three criteria for planets and this was the only one Pluto didn't make. Three other dwarf planets were also named, Pluto's moon Charon, Xena, and that is the two I can remember.

Answer 5

You that scientist had discovered three new planets but they are removed from the list of planets . And the pluto which was the 9 planet is also removed because that is declared an Asteroid not a planet so we have only 8 planets. Pluto is leaving its orbit.

Answer 6

Astronomers decided it wasn't a planet because as they researched the milky way further they found that there were alot of similar planet-like planets. Plus, pluto is just a big blob of ice. =]

Answer 7

Modern scientists have decided to change the policy regarding planets that have been enforced since we have had planets!@

Answer 8

Because it is considered a Dwarf planet

Answer 9

they found more "things" just like pluto so if they named pluto a planet they would have to name alll of those things planets too

Answer 10

Maybe because Astronomers needed a new issue to talk about. It's been awhile since the rover landed on Mars and space-tourism isn't cutting it...