Pluto's Wobbly Egg-Shaped Moons
on 04 June 2015
Pluto is turning out be a weirder dwarf planet than expected. Not only is one of its moons almost as large as the planet itself, but its two other moons wobble through space. The Hubble Space Telescope has captured images of the oblong moons—Nix and Hydra—tumbling like two poorly thrown footballs as they orbit Pluto and Charon—the other massive moon. The wobbling is due to the shifting gravitational fields from the Pluto-Charon system and is exacerbated by their egg-like shapes.