Pluto

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Why Is Pluto No Longer a Planet?

Summary Pluto isn’t alone—it’s part of the Kuiper Belt with possibly hundreds of other planet-sized objects. Because Pluto hasn’t achieved gravitational dominance in its region, the International Astronomical Union’s 2006 definition of a planet means it no longer qualifies. Pluto’s classification change remains controversial, with critics challenging the voting process and planetary enthusiasts struggling to let go of their long-lived…