"Planet 10" is a hypothetical celestial body that some scientists believe may exist beyond the orbit of Neptune. It is thought to be part of our solar system and could explain certain gravitational effects observed in the orbits of distant objects in the Kuiper Belt. The concept of Planet 10 emerged from studies of these distant objects, suggesting that a large, unseen planet could be influencing their paths. While no direct evidence of Planet 10 has been found, astronomers continue to search for it using advanced telescopes and observational techniques.