Discovery of Hydra

Hydra is the outermost of the known moons of Pluto, found together with Nix in images taken by the Hubble Space Telescope by a team that included Hal Weaver and Alan Stern. It is named for the many-headed serpent of Greek mythology, and the first letter of its name, like Nix's, honours the New Horizons mission. Hydra is a small, irregularly shaped body only a few tens of kilometres across, and its orbit is nearly circular. The spacecraft imaged it in 2015, showing a surface that is bright and made largely of water ice, with a few craters visible.

Open on the timeline