Moons of Pluto meters per pixel were returned of Nix and up to 1.1 kilometers per pixel of Hydra. Lower-resolution images were returned of Styx and Kerberos. Author Edmond Hamilton referred to three moons of Pluto in his 1940 novel "Calling Captain Future", naming them , , and . Charon was listed as the largest of them. All three moons would not be discovered until the year 1970, according to Hamilton. The real Charon was discovered in 1978. Moons of Pluto The dwarf planet Pluto has five moons down to a detection limit of about 1 km in diameter. In order of distance
Naming of moons The initial "S/" stands for "satellite", and distinguishes from such prefixes as "D/", "C/", and "P/", used for comets. The designation "R/" is used for planetary rings. These designations are sometimes written like "S/2003 S1", dropping the second space. The letter following the category and year identifies the planet (Jupiter, Saturn, Uranus, Neptune; although no occurrence of the other planets is expected, Mars and Mercury are disambiguated through the use of Hermes for the latter). Pluto was designated by P prior to its recategorization as a dwarf planet. When the object is found around a minor planet, the identifier used