Hydra
Hydra (Natural satellite). See its size, orbit and live position on a 3D map of the Solar System. Hydra, formal designation (134340) Pluto III, is a natural satellite of Pluto, with a diameter of approximately 51 km (32 mi) across its longest…
Hydra, formal designation (134340) Pluto III, is a natural satellite of Pluto, with a diameter of approximately 51 km (32 mi) across its longest dimension. It is the second-largest moon of Pluto, being slightly larger than Nix. Hydra was discovered along with Nix by astronomers using the Hubble Space Telescope on 15 May 2005, and was named after the Hydra, the nine-headed underworld serpent in Greek mythology. By distance, Hydra is the fifth and outermost moon of Pluto, orbiting beyond Pluto's fourth moon Kerberos.
- Type: Natural satellite
- Orbiting: Pluto
- Diameter: 37 km
- Orbital period: 38.2 days