The Criteria for a Planet:
1. Orbits the Sun: Pluto does orbit the Sun, so it checks this box.
2. Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape: While Pluto is nearly round, it's not perfectly spherical.
3. Has cleared the neighborhood around its orbit: This is where Pluto falls short. Its orbit is shared with many other icy bodies in the Kuiper belt, meaning it hasn't "cleared" its path.
Pluto's Status:
Pluto's classification was debated for years, but in 2006, the International Astronomical Union (IAU) established the official definition of a planet, which Pluto didn't meet. Because of this, it was reclassified as a dwarf planet, along with other celestial bodies like Eris and Ceres.
Key Takeaway: Pluto doesn't have enough gravitational dominance in its orbital region to be considered a planet. It shares its space with numerous other objects, leading to its reclassification as a dwarf planet.
