Hydra

Also known as (134340) Pluto III, Pluto III, S/2005 P 1

outermost known natural satellite of Pluto

AI overview

Hydra is the outermost known natural satellite, or moon, of Pluto, the distant dwarf planet in our solar system. It matters because studying it helps us understand the system of moons around Pluto and the composition of objects in the outer reaches of our solar system.

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Wikidata facts

Radius: 57.5
Mass: 50000000000000000
Orbital period: 38.206
Image: Hydra 14.07.2015.jpg

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provisional designation: S/2005 P 1
time of discovery or invention: 2005-05-15
Commons category: Hydra (moon)
orbital eccentricity: 0.0051
semi-major axis of an orbit: 64749
orbital inclination: 0.242
temperature: 55
albedo: 0.35
apparent magnitude: 23.38
IPA transcription: ˈhyːdʁa

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Article

Hydra, formal designation (134340) Pluto III, is a natural satellite of Pluto, with a diameter of approximately 51 km (32 mi) across its longest dimension. It is the second-largest moon of Pluto, being slightly larger than Nix. Hydra was discovered along with Nix by astronomers using the Hubble Space Telescope on 15 May 2005, and was named after the Hydra, the nine-headed underworld serpent in Greek mythology. By distance, Hydra is the fifth and outermost moon of Pluto, orbiting beyond Pluto's fourth moon Kerberos.

Hydra has a highly reflective surface caused by the presence of water ice, similar to other Plutonian moons. Hydra's reflectivity is intermediate, in between those of Pluto and Charon. The New Horizons spacecraft imaged Pluto and its moons in July 2015 and returned multiple images of Hydra.