What was once considered a major planet now lives among the name of a dwarf planet. Pluto was named after the Greek god of the underworld. An 11-year-old schoolgirl named Venetia Burney saw the planet and then proposed the name and it stuck. Pluto has five known moons. They are Charon (discovered in 1978,), Hydra and Nix (both discovered in 2005), Kerberos originally P4 (discovered 2011) and Styx originally P5 (discovered 2012) official designations S/2011 (134340) 1 and S/2012 (134340) 1.