Styx (moon) in the context of "Moons of Pluto"

Nix, formal designation (134340) Pluto II, is a natural satellite of Pluto, with a diameter of 49.8 km (30.9 mi) across its longest dimension. It was discovered along with Pluto's outermost moon Hydra on 15 May 2005 by astronomers using the Hubble Space Telescope, and was named after Nyx, the Greek goddess of the night. Nix is the third moon of Pluto by distance, orbiting between the moons Styx and Kerberos.

Nix was imaged along with Pluto and its other moons by the New Horizons spacecraft as it flew by the Pluto system in July 2015. These images reveal a large reddish area on Nix that is likely an impact crater.

Kerberos, formal designation (134340) Pluto IV, is a small natural satellite of Pluto, about 19 km (12 mi) in its longest dimension. Kerberos is also the second-smallest moon of Pluto, after Styx. It was the fourth moon of Pluto to be discovered and its existence was announced on 20 July 2011. It was imaged, along with Pluto and its four other moons, by the New Horizons spacecraft in July 2015. The first image of Kerberos from the flyby was released to the public on 22 October 2015.