After Pluto was discovered in 1930, it was ninth planet of Solar System. It has five moons, Charon, Styx, Nix, Kerberos, and Hydra. Since 2006, it was reclassified as dwarf planet, as other even bigger object are known in Kuiper bel, like dwarf planet Eris.

As most planets orbiting Sun, it was named after Roman god of the underworld, Pluto. Name was proposed by 11-year-old girl, Venetia Burney (1918–2009)¹⁾.

Pluto orbit varies between 30 and 49 Astronomical Units (AU), 4.4–7.4 billion km from the Sun, with period of 247.94 Earth years. This means that between discovery, and downgrade from the planet status, even not one-third of plutonian year passed²⁾.