How big are the moons Charon Hydra and Nix?
Pluto has three known moons as of 2009. Charon is relatively large at 1,206 km in diameter (about half the diameter of Pluto), and was discovered in 1978 by Jim Christy. The other two, Hydra and Nix, were discovered in 2005 by a team using the Hubble Space Telescope. Hydra and Nix are estimated to be about 50 to 150 km in diameter, with Nix probably the smaller of the two.