Pluto is no longer considered a planet because the International Astronomical Union (IAU) downgraded its status to that of a "dwarf planet" in August 2006. This decision was made because Pluto did not meet the three criteria set by the IAU for a celestial body to be classified as a planet. These criteria include that a planet must orbit the Sun, be spherical in shape, and have cleared its neighborhood of other objects. While Pluto meets the first two criteria, it fails to meet the third one, as it has not managed to clear its neighboring region of other objects. As a result, it was reclassified as a dwarf planet, and only the rocky worlds of the inner Solar System and the gas giants of the outer system are now designated as planets.
The decision to reclassify Pluto sparked widespread debate and controversy, with many people objecting to the change on the basis of tradition and history rather than engaging with the scientific reasoning behind the reclassification. Despite the ongoing debate, it is unlikely that the IAU will revisit the controversy and reclassify Pluto as a planet again in the near future.
