As of 2014, Pluto has five recognized moons. The largest moon, Charon, was discovered in 1978, followed by the discoveries of Nix and Hydra in 2005, Kerberos in 2011 and Styx in 2012. Pluto may have as many as 10 moons.
The moon Charon is quite massive in comparison to Pluto. Pluto and Charon are widely considered a double dwarf planet system rather than a dwarf planet and moon. The anticipated arrival of the probe New Horizons in 2015 is expected to lead to the discovery of additional Plutonian moons. The prevailing theory is that the moons were created from the debris of a massive collision.