Styx

satellite of Pluto

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July 20, 2026

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Styx is one of Pluto's five known moons. It is much smaller than Pluto's largest moon, Charon, and is elongated in shape. Styx orbits Pluto outside of Charon's path in a nearly circular orbit and in the same orbital plane as Charon. The moon was discovered in 2012 using the Hubble Space Telescope.123

In Greek mythology, Styx is known as one of the rivers of the underworld. The gods swore by its waters as their most binding oath.45

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Christening Pluto’s Moons
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…
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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…
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Pluto
Pluto’s moons
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…
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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…
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New Horizons
…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.
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…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.
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