How many moons does Pluto have?

Pluto has five known moons:

1. Charon, the largest one, Charon was discovered in 1978.
2. Hydra, very small
3. Nix, very small, and two more-newly discovered small moons. and Nix/Hydra were identified in 2005.
4. Kerberos (provisionally named P4 or S/2011-134340)
5. Styx (S/2012-134340). On July 11, 2012, it was announced that a team of astronomers, using NASA's Hubble Space Telescope, discovered a fifth moon orbiting Pluto. The moon is provisionally designated as S/2012 (134340) 1. The moon was discovered by astronomers using nine sets of images taken by the Wide Field Camera 3 fitted to the Hubble Telescope between June 26, 2012 and July 9, 2012. It is estimated to be an irregular shape and 6 to 15 miles across.

The largest moon, Charon, is proportionally larger compared to its primary than any other satellite of a known planet or dwarf planet in the solar system. In fact there is some discussion as to whether we should consider this a "binary system" instead of a dwarf planet with moons because Charon is so massive that the barycenter (center of gravity around which the bodies rotate) of the Pluto-Charon group is not inside either of those bodies.