Celestial Objects

Hydra

Moons

Citation Formats

General Reference

Space and Astronomy Atlas. "Hydra." Accessed September 2, 2026. https://space.interactiveatlas.org/celestial-objects/hydra-moon.

APA Style

Space and Astronomy Atlas. (n.d.). Hydra. Retrieved September 2, 2026, from https://space.interactiveatlas.org/celestial-objects/hydra-moon

BibTeX

@misc{spaceandastronomyatlas-hydra,
  author = {Space and Astronomy Atlas},
  title = {Hydra},
  year = {2026},
  url = {https://space.interactiveatlas.org/celestial-objects/hydra-moon},
  note = {Accessed September 2, 2026}
}

Hydra, formally designated Pluto III, is the second-largest moon of Pluto, slightly bigger than Nix, with a diameter of about 51 kilometers across its longest dimension. It was discovered alongside Nix on 15 May 2005 by astronomers using the Hubble Space Telescope and was named for the nine-headed serpent of the underworld in Greek mythology; by distance it is the outermost of Pluto's five known moons, orbiting beyond Kerberos.

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