Hydra (moon) the Hydra, the nine-headed serpent that battled Heracles in Greek mythology. The nine heads of Hydra are a reference to Pluto's tenure as the ninth planet; its initial, "H", refers to the Hubble Telescope, which discovered Hydra and, together with Nix, to the "New Horizons" mission whose safe passage was the motivation for taking the Hubble images. Hydra orbits the barycenter of the system in the same plane as Charon and Nix, at a distance of about 65,000 km. Its eccentricity of 0.0059 is small, but significantly non-zero, and the largest of those of Pluto's small moons (slightly larger than
Hydra (Within Temptation album) made the cover for "The Unforgiving". The album title refers to the great variation in musical genres the band improves on with each new release. About the concept, guitarist Robert Westerholt says: ""Hydra" is a perfect title for our new album, because like the monster itself, the record represents the many different sides of our music." According to the ancient Greek mythology, the Hydra was a giant multi-headed serpent that, for each severed head, sprang forth two more in their place. As the title, the sound composition of the album was said to be varied, as Westerholt said, also referring