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
Dragons in Greek mythology where it became the constellation Draco. Dragons in Greek mythology Dragons play a significant role in Greek mythology. The word dragon derives from the Greek δράκων (drakōn) and its Latin cognate draco. Ancient Greeks applied the term to large, constricting snakes. Daniel Ogden speaks of three ways to explain the origins of Greek dragon myths: as "vertical" evolution from (reconstructed) Proto-Indo-European mythology, as "horizontal" adaptation from Ancient Near Eastern mythology, or as sitting within "the cloud of international folktale". Regarding theories of vertical transmission, Ogden argues that they carry "an unspoken assumption that prior to such a transfer the Greeks'