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
Greek ironclad Hydra broke out into the Aegean sea; the assumption was that the Greeks would dispatch "Georgios Averof" to hunt down "Hamidiye". Despite the threat to Greek lines of communication posed by the cruiser, the Greek commander refused to detach "Georgios Averof" from her position. "Georgios Averof" appeared approximately 12 miles from Lemnos; when the powerful Greek ship was spotted, the Ottomans turned to retreat with "Georgios Averof" in pursuit. She scored several hits on the fleeing Ottoman ships before breaking off the chase. "Hydra" and her sisters were too slow to keep up with "Georgios Averof", and played no part in