[3] It was discovered along with Pluto's outermost moon Hydra on 15 May 2005 by astronomers using the Hubble Space Telescope,[1] and was named after Nyx, the Greek goddess of the night.

[12] Images from the New Horizons spacecraft reveal a large reddish area on Nix that is likely an impact crater.

[13] Nix was independently discovered by Max Mutchler and Andrew Steffl, members of the Pluto Companion Search Team, using the Hubble Space Telescope.

[14] Since Nix's brightness is about 5,000 times fainter than Pluto, long exposure images were taken in order to find it.

The names of features on the bodies in the Pluto system are related to mythology and the literature and history of exploration.

[20] Pluto's smaller moons, including Nix, were thought to have formed from debris ejected from a massive collision between Pluto and another Kuiper belt object, similarly to how the Moon is believed to have formed from debris ejected by a large collision of Earth.

[24] Contrary to this, other studies show that Nix is spectrally neutral, similar to the small moons of Pluto.

[12] In this case, tholins on the surface of Nix may have originated from the reaction of methane with ultraviolet radiation from the Sun.

[12] Derived from crater counting data from New Horizons, the age of Nix's surface is estimated to be at least four billion years old.

[22] The chaotic tumbling of Nix is also strengthened by its elongated shape, which creates torques that act on the object.

[2][24] A hypothesis explaining such a near-resonance is that the resonances originated before the outward migration of Charon following the formation of all five known moons, and is maintained by the periodic local fluctuation of 9 percent in the Pluto–Charon gravitational field strength.

Of Pluto's smaller moons, only Nix and Hydra were imaged at resolutions high enough for surface features to be visible.

[25] Enhanced color images from the Ralph MVIC instrument of New Horizons show a reddish region on its surface.