* Astronomy

Hydra is the second outermost known natural satellite of Pluto. It was discovered along with Nix in June 2005, and is to be visited along with Pluto by the New Horizons mission in July 2015.
The name Hydra was announced on June 21, 2006, in IAU Circular 8723, along with the formal designation Pluto III. It was named after Hydra, the nine-headed serpent who battled Hercules in Greco-Roman Mythology. 
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