Q:

Why is Pluto not a planet?

A:

Quick Answer

In 2006, the International Astronomical Union changed Pluto's classification from a planet to a dwarf planet because the planet has not cleared its orbit of other objects. When a planet clears its orbit, all other objects on the orbital path are either drawn into the planet's gravitational pull or flung away from it and out of the orbit.

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Why is Pluto not a planet?
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Full Answer

The change in classification came after the discovery of the dwarf planet Eris in 2005. Eris is more massive and Pluto and orbits the sun, so its discovery challenged the notion of a nine-planet solar system. To account for the discovery of Eris and the subsequent discovery of other bodies, the International Astronomical Union created the dwarf planet classification. By definition, Pluto best matches the characteristics of a dwarf planet and was reclassified as one. Pluto could potentially clear its orbit in the future, most likely by colliding with other objects in its orbit and combining with them, which would give it back its planet classification. As of 2014, the other named dwarf planets besides Pluto and Eris are Ceres, Makemake and Haumea. According to NASA, there may be over 100 as-yet undiscovered dwarf planets in the solar system, which covers objects with sufficient mass to achieve a round shape and that orbit the sun.

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Related Questions

  • Q:

    How many miles is Pluto from the sun?

    A:

    Pluto is considered a dwarf planet, and it is about 3.7 billion miles from the sun. Until it was reclassified in 2006, Pluto was the ninth and furthest planet from the sun.

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  • Q:

    What are some interesting facts about Pluto?

    A:

    Pluto is a dwarf planet in the area of the Kuiper belt, which is an area with many dwarf planets, according to the National Aeronautics and Space Administration (NASA). The dwarf planet is after Neptune in the planetary alignment, and it is the former ninth planet until reclassification in 2006, clarifies the Space Telescope Science Institute.

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  • Q:

    What is Pluto named after?

    A:

    The planet Pluto is named after Pluto, the god of the underworld in Greek and Roman mythology. The name was suggested by a young girl, Venetia Burney Phair, in 1930 when she heard the news that a new planet had been discovered in the solar system.

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  • Q:

    Why isn't Pluto a planet any more?

    A:

    As of 2014, Pluto isn't considered a planet because of its size and location in space. In 2003, when an astronomer found an object in space that was beyond Pluto and also larger than Pluto, it caused scientists to reconsider what constitutes a planet.

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