Pluto family grows by two Lunacy: Kerberos (P4) and Styx (P5) named as moons of Pluto. About two years ago, a team of researchers was using the Hubble Space Telescope to determine if there were any thin dust rings around the dwarf planet Pluto. The long exposure images showed no traces of dust rings, but there was a hidden surprise. The images captured two new and unknown moons. They were given working designations of P4 and P5, as three moons had already been discovered at Pluto: Charon, Nix and Hydra. The SETI Institute decided to open the debate to the public on what to christen these two little moons by conducting a popular vote. The International Astronomical Union has strict conventions for naming Solar System objects, and, in Pluto's case, its moons were required to have names from the Greek mythology associated with him. This was already in use with Charon (the boatman ferrying dead souls), Nix (after Nyx, the goddess of night) and Hydra (the giant nine-headed serpent guarding an entrance to the underworld). A list of 21 candidates was arrived at and even included Vulcan, a suggestion made by William Shatner - Captain Kirk of Star Trek fame, in honour of Mr Spock's fictitious planet.The committee didn't consider Vulcan part of the Pluto myth and went for the next two best-supported candidates and made the results public last week. P4 is now Kerberos, Pluto's three-headed dog guarding the exit to the underworld, and P5 is Styx, the river crossed by the dead to get there. This brings the total of known Solar System moons to 173. We'll have a family portrait of Pluto and its moons when the New Horizons spacecraft arrives there in July 2015.