Nix

Moon· orbits Pluto

Nix is a small, elongated moon of Pluto with a bright water-ice surface and a chaotic, tumbling rotation, discovered in 2005.

Open in 3D viewSee Nix in the live, interactive 3D map

Key facts

Mass (est.)

2.25 × 10¹⁶ kg

0.000000306 Moon masses

Radius

18 km

1% of our Moon's radius

Surface gravity

0.00463 m/s²

0% of Earth's

Orbit around Pluto

24.85 Earth days

Science

Physical

Mass (estimated): 2.25 × 10¹⁶ kg · 0.000000306 Moon masses
Radius: 18 km · 1% of our Moon's radius
Surface gravity: 0.00463 m/s² · 0% of Earth's
Escape velocity: 12.9 m/s · 0% of Earth's

Orbit around Pluto

Distance from Pluto: 34,443 km
Orbital period: 24.9 days
Eccentricity: 0.015
Inclination: 0.00 °

Rotation

Rotation: Chaotic — Nix tumbles unpredictably, its spin constantly reshuffled by the shifting pull of the Pluto–Charon binary, with no fixed period (Showalter & Hamilton 2015). Not tidally locked.

Composition

Bulk composition: A predominantly water-ice surface; small and irregular, with a reddish patch.

Radiation & temperature

Insolation: 0.00079 S⊕ · 1/1,266 of the sunlight Earth receives
Geometric albedo: 0.56
Equilibrium temperature: 38 K (-235 °C)

Discovery & history

By: the Hubble Space Telescope Pluto Companion Search Team (Hal Weaver, Alan Stern and colleagues)
Method: Photographic plates
Name: Nyx, the Greek goddess of night and mother of Charon; the initials N and H also honour the New Horizons mission.

Nix was discovered, with Hydra, in Hubble Space Telescope images taken in May 2005 during a search for moons around Pluto ahead of the New Horizons flyby. A small, elongated moon, it tumbles unpredictably through the shifting gravity of the Pluto–Charon binary, and a reddish patch hints at a history unlike its icy surface. Beyond its discovery and the 2015 flyby, little detail is known.

Images

Pluto's moon Nix, imaged by New Horizons — NASA / Johns Hopkins APL / SwRI (public domain) · Wikimedia Commons

Pluto Moon Nix, Half Illuminated — NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute · NASA Image Library

Pluto and its Moons: Charon, Nix, and Hydra — NASA, ESA, H. Weaver JHUAPL, A. Stern SwRI, and the HST Pluto Companion Search Team · NASA Image Library

Capturing Nix and Hydra — NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute · NASA Image Library

Family Portrait of Pluto Moons — NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute · NASA Image Library

Hubble Finds Two Chaotically Tumbling Pluto Moons — artist's impression, not a photograph — NASA/GSFC · NASA Image Library

Final Hazard Search — NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute · NASA Image Library

All Clear for New Horizons — artist's impression, not a photograph — NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute · NASA Image Library

Images from open archives · credit shown per image