Hydra

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Hydra
Hydra is the outermost known moon of Pluto. Hydra is in a 2:3 orbital resonance with Nix, and a 6:11 resonance with Styx . As a result of this "Laplace-like" 3-body resonance, it has conjunctions with Styx and Nix in a 5:3 ratio. Like Saturn's moon Hyperion, Nix, and the other small Plutonian moons, Hydra rotates chaotically; its day length and rotational axis vary quickly over astronomical timescales, to the point that it regularly flips over. Hydra (moon) - Wikipedia, the free encyclopedia
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Short Description Hydra is the outermost known moon of Pluto. Hydra is in a 2:3 orbital resonance with Nix, and a 6:11 resonance with Styx . As a result of this "Laplace-like" 3-body resonance, it has conjunctions with Styx and Nix in a 5:3 ratio. Like Saturn's moon Hyperion, Nix, and the other small Plutonian moons, Hydra rotates chaotically; its day length and rotational axis vary quickly over astronomical timescales, to the point that it regularly flips over. Hydra (moon) - Wikipedia, the free encyclopedia
Discovered by Hubble Space Telescope, Pluto Companion Search Team
Discovery date 15 June 2005
Type Moon
AddInfo Pluto III
Satellite of Pluto
Minor planet number 134340 Pluto III
Orbit Prograde
Rotation Direct
Apoapsis 05 65 117 km
Periapsis 05 64 443 km
Semi-major axis 05 64 738 km
Distance from Sun 02 39.54 au /5
Eccentricity 0.005 862
Orbital period 38.201 77 days
Orbital speed  0.1233 km/s
Inclination to the equator 000.242
Diameter/Size 02 47 km
Dimensions 65 km × 45 km × 25 km
Mass 1016×4.8 ± 4.2 kg
Surface gravity  0 m/s2
Escape velocity  0 m/s
Rotation period 0.4295 ± 0.0008 days (chaotic)
Axial tilt variable
Albedo geometric 0.83 ± 0.08
Temperature mean 02 44 K | −229 °C
Apparent magnitude 22.9–23.3
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