Question

Our solar system has nine planets pluto the ninth planet is no more considered as a part of our solar system why

Answer 1

Hi mate!!
because it has gone too far from the sun. it still revolves around the sun but it had made itself too far from our solar system . and also it is too small in size so we cannot consider it as a planet . it is now considered as a dwarf planet.
Hope it will help you.

Answer 2

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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 define a full-sized planet. Essentially Pluto meets all the criteria except one—it “has not cleared its neighboring region of other objects.”