why pluto is not a planet
why pluto is not a planet Pluto was once considered a planet, but in 2006, the International Astronomical Union (IAU) redefined the criteria for what qualifies as a planet. According to the new definition, a planet must meet three criteria:It must orbit the sun. It must be spherical in shape, meaning it has sufficient mass for its gravity to pull it into a roughly round shape. It must have cleared its orbit of other debris. Pluto meets the first two criteria, but it fails the third. Pluto's orbit is not clear of debris, as it shares its orbit with other small icy bodies in the Kuiper Belt. Therefore, Pluto is now classified as a "dwarf planet," which is a new category of objects in our solar system that share some characteristics with planets but do not meet all the criteria to be considered full-fledged planets.