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Pluto does not meet all three criteria that now define a planet. A planet must orbit around the Sun, have sufficient mass to maintain a nearly round shape, and it must have cleared the neighborhood around its orbit.
Pluto has not cleared the neighboorhood around its orbit. It has been reclassified as a "dwarf planet". More >>

en.wikipedia.org/wiki/Pluto

Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of ... The IAU has not formalized a definition for binary dwarf planets, and Charon is officially classified as a moon of Pluto. ..... backward in time), after intervals longer than the Lyapunov time of 10–20 million years, calculations become ...

wonderopolis.org/wonder/why-is-pluto-no-longer-a-planet

The truth is, nothing about Pluto changed, but the definition of a planet did. Once these changes became official, Pluto no longer fit the definition of a planet.

www.bbc.com/news/science-environment-33462184

Jul 13, 2015 ... In 2006, Pluto was demoted from planet status. Why was it removed from the planet club?

www.universetoday.com/13573/why-pluto-is-no-longer-a-planet

Nov 27, 2009 ... Let's find out why Pluto is no longer considered a planet. Pluto was first discovered in 1930 by Clyde W. Tombaugh at the Lowell Observatory in ...

www.loc.gov/rr/scitech/mysteries/pluto.html

The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to ...

www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-pluto-k4.html

Pluto is a dwarf planet in our solar system. ... But Pluto does not orbit in a circle. The orbit of Pluto ..... Large debris could be satellites that are no longer working.

www.planetsforkids.org/why-is-pluto-no-longer-a-planet.html

Pluto used to be known as the smallest planet in our solar system, and the furthest planet from the sun. Pluto was discovered in 1930 by Clyde Tombaugh, ...

news.nationalgeographic.com/news/2006/08/060824-pluto-planet.html

Aug 24, 2006 ... Pluto is no longer a planet, according to a new official definition. Instead the icy sphere will be considered one of more than 40 "dwarf planets."

zidbits.com/2011/04/why-is-pluto-no-longer-a-planet

Apr 18, 2011 ... In 2006, astronomers around the world made a decision that demoted Pluto's status as a planet. Today we're going to explore why they did it.