Pluto

1. Dwarf planet orbiting the sun once ever 250 Earth years on an eccentric orbit taking it from about 2,757 to 4,583 million miles out, or from nearly thirty to almost fifty times Earth's distance. For twenty of those years it is closer to the sun than Neptune; it was last at the closest point in 1989. Diameter, 1485 miles. Surface temperature by recent measurement 230 degrees Centigrade below freezing. Maximum air pressure is 700,000 times less than Earth's. Composition largely rock and various ices. Closely orbited by its comparatively large moon Charon (diameter 753 miles); the centre of mass of the system, around which both bodies orbit, is above Pluto's surface and both bodies are tidally locked on one another, always keeping the same faces inwards; there are at least two other moons, Nix and Hydra, discovered in 2005. Pluto rotates on its axis, and is orbited by Charon, roughly every six Earth days and nine hours. Pluto is at least five hundred times less massive than Earth (a body that many times more massive than Earth would outweigh Jupiter) and smaller than seven moons in the system, including our own Moon. Officially the ninth planet from its discovery by Clyde Tombaugh in 1930, with the discovery of several similar-sized bodies in the outer system Pluto was demoted to the newly-created dwarf planet category in 2006. Gives its name to the highly toxic synthetic element plutonium, atomic number 94. 2. Roman god of the Underworld, connected by parallel with the Greek Hades. The Roman Pluto (or more accurately Plutus) was more a divinity of the riches found under the earth such as silver and gold and hence a god of wealth, as referenced in the latter-day term plutocracy (political rule by the wealthy). Because these substances were mined from a physical underworld, Pluto is often associated as well with a spiritual underworld, or the land of the dead, hence the latter-day link to Hades. 3. Also spelt Plouto, a nymph in Greek mythology, the mother of Tantalus by Zeus. The daughter of Oceanus and Tethys. 4. Mickey Mouse's pet dog. Introduced in Disney's cartoons in 1930, the year of the dwarf planet's discovery, hence the name. A relatively naturalistic character, as opposed to the anthropomorphic dog Goofy. 5. An inbred mutant from the film franchise The Hills Have Eyes.