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
Lerna Helladic period, shaft graves were cut into the tumulus of the House of Tiles, indicating that the significance of that monument had been forgotten. Lerna was used as a cemetery during the Mycenaean age, but was abandoned about 1250 BCE. Ceramics of Lerna III include the hallmark spouted vessels that archaeologists name "sauceboats", with rims that sweep upwards into a curved spout, as well as bowls with incurving rims, both flat-bottomed and with ring bases, and wide saucers, sometimes with glazed rims, more pleasant for the drinker's lips. Jars and hydria have swelling curves. Painted decoration is sparse; stamped sealing