Pluto was originally classified as the ninth planet in our solar system after its discovery in 1930. However, in 2006, the International Astronomical Union (IAU) redefined what constitutes a planet. According to the new definition, a planet must meet three criteria:
- It must orbit the Sun.
- It must be massive enough to assume a nearly round shape.
- It must have cleared its orbit of other debris and objects.
Pluto meets the first two criteria but fails the third because it shares its orbital neighborhood with other objects in the Kuiper Belt and has not cleared its orbit of debris. Because of this, Pluto was reclassified as a "dwarf planet" rather than a full planet
. This reclassification was controversial and met with public disappointment, but it reflected advances in our understanding of the solar system and the discovery of other similar-sized objects beyond Neptune. Despite losing its planet status, Pluto remains an intriguing world with complex geology, a thin atmosphere, and five known moons, including Charon, which is unusually large relative to Pluto itself. NASA's New Horizons mission in 2015 provided detailed images and data revealing Pluto's surprising geological activity and complexity
. In summary, Pluto is still a fascinating celestial body but is no longer classified as a planet because it does not dominate its orbital zone, leading to its status as a dwarf planet since 2006.
