New York Times | Two of Pluto's Moons Get Names From Greek Mythology's Underworld New York Times On Tuesday the International Astronomical Union announced names for two of these moons, the fourth and fifth to be discovered. Moon No. 4 is now Kerberos, after the many-headed dog that guarded the entrance to the underworld in Greek mythology. Pluto Moons Named Styx & Kerberos After Greek Myths Despite Trekkies' Votes Straight from the Greek, Snubbing Star Trek Fans; Pluto's Moons Get Graduated ... Meet Pluto's smallest moons: Kerberos and Styx |