Recent findings from the New Horizons team reveal that Pluto’s third-largest satellite Nix is covered in the purest water ice yet observed in the dwarf planet system, even purer in spectra than what was seen on its slightly larger sibling Hydra. This analysis further supports the hypothesis that Pluto’s moons were created in an impact event that formed the Pluto-Charon system, over 4 billion years ago.
Whether you want to call it a planet, dwarf planet, Kuiper Belt Object, or some or none of the above, there’s no denying that Pluto and its family of moons are true curiosities in the Solar System. Not only does little Pluto have one moon — Charon — that’s so massive in comparison that they both actually orbit each other around a central point outside the radius of either (if you feel like adding “binary” to whatever term you prefer to use, go right ahead) but it also has four other smaller moons in orbit that kinda sorta break the rules of how moons are “supposed to” behave.
Scientists using the Hubble Space Telescope have identified a new moon in orbit around distant Pluto. Estimated to be between 8 to 21 miles (13 to 31 km) in diameter the moon has been designated P4… at least until a more fitting name can be decided upon.
P4 lies between the orbits of Nix and Hydra, two moons discovered in 2005. It completes an orbit around Pluto about every 31 days.
Pluto’s largest moon Charon is 648 miles (1,043 km) across. Nix and Hydra are each about 20 to 70 miles (32 to 113 km) wide.
Read the press release here.
Credit: NASA, ESA and M. Showalter (SETI Institute)