Nix

Nix is one of the most distinctive moons in the Pluto system, known for its high reflectivity and its "jellybean" appearance. While it shares some traits with its sibling moon Hydra, Nix has unique geological and physical characteristics that make it stand out.

The "Jellybean" Moon

Nix is far from a perfect sphere. Because it is small, it lacks the gravitational strength to crush itself into a round shape. Instead, it is elongated and irregular, measuring approximately 50 km by 35 km by 33 km (31 x 22 x 21 miles). This shape has led many astronomers to compare it to a jellybean or a thick pancake.

The Red Spot: Gleti Crater

The most famous feature on Nix is a large, reddish region known as Gleti. This feature is believed to be a massive impact crater.

• Why is it red? Scientists believe the impact was powerful enough to excavate material from beneath the moon's icy surface.

• Tholins: This deeper material likely contains methane ices that, when exposed to solar radiation, transform into complex organic molecules called tholins, which have a distinct rusty-red hue.

• Contrast: This red "bullseye" stands out sharply against the rest of the moon's surface, which is mostly neutral grey or white.

Chaotic Rotation

Unlike the Earth’s Moon, which always shows us the same face, Nix is in a state of chaotic rotation.

• The "Tumble": Because Nix orbits a "double planet" system (Pluto and the massive moon Charon), the gravity fields are constantly shifting.

• Unpredictability: This prevents Nix from becoming "tidally locked." Instead, it wobbles and flips as it travels. On Nix, the Sun would appear to rise and set in different parts of the sky on different days, and the length of a "day" would constantly change.

Brightness and Composition

Nix is surprisingly bright for its size, reflecting about 56% of the light that hits it. This high albedo (reflectivity) is due to its surface being covered in nearly pure water ice. This makes it look like a giant, dirty snowball tumbling through the dark of the Kuiper Belt.

Characteristics:

Diameter - ~49.8 km (longest axis)

Surface - Water ice

Discovery - 2005 (Hubble Space Telescope)

Orbit Period - ~24.9 Earth days

Major Feature - Gleti Crater (Red Spot)