Styx

Styx is the smallest and innermost of Pluto's five known moons. Much like Kerberos, it was a "bonus" discovery found while astronomers were double-checking the neighborhood to ensure the New Horizons spacecraft wouldn't collide with any hidden debris.

It was discovered in 2012, just one year before the mission arrived at the Pluto system.

The "Tiny" Stats

Because Styx is so small and far away, getting a clear picture of it was incredibly difficult. Even the best shots from New Horizons show it as a tiny, bright speck.

• Size: Styx is roughly 3 to 10 miles (5 to 16 km) across. It’s essentially a giant space rock.

• Shape: It is highly irregular and elongated, often described as having a "football" or "pill" shape.

• Surface: Like the other small moons, it is thought to be covered in highly reflective water ice, which makes it surprisingly bright despite its tiny size.

A Chaotic Orbit

Styx lives in a very crowded and gravitationally complex environment.

1. The Inner Circle: It orbits Pluto at a distance of about 26,000 miles (42,000 km). This places it between the large moon Charon and the smaller moon Nix.

2. The "Lego" Effect: Styx and the other small moons (Nix, Kerberos, Hydra) are likely the shrapnel left over from a massive collision billions of years ago between Pluto and another large object.

3. Tumbling through Space: Because Styx orbits the "binary" center of mass between Pluto and Charon, it doesn't have a stable rotation. It tumbles and spins wildly rather than keeping one side locked toward Pluto. If you stood on Styx, the Sun might rise in the east one day and the north the next!

Why the Name?

Following the theme of the Greek underworld, Styx is named after the mythological river that separates the world of the living from the world of the dead. It was also named after the goddess of that same river.