Styx

Encyclopaedia Britannica As mentioned elsewhere in this list, Styx—the name of Pluto’s most recently discovered moon and almost certainly the last moon to be discovered by means of the Hubble Space Telescope—is best-known as one of the rivers of the Underworld. Hesiod identified Styx as the…

Nix, Kerberos, and Styx—are much smaller than Charon. All four are elongated. They revolve around Pluto outside Charon’s path in nearly circular orbits (like Charon) and in the same orbital plane as Charon. The orbital radius of Hydra is about 64,721 km (40,216 miles); that of Kerberos is…

…four smaller moons of Pluto—Styx, Nix, Kerberos, and Hydra—were found to be spinning very rapidly, unlike most other satellites in the solar system, which keep one side facing the planet they orbit.