The Hubble Telescope has added another great discovery to its repertoire; a fourth moon for Pluto. Temporarily assigned the name P4, it was discovered just this month orbiting around the dwarf planet with Charon, Nix, and Hydra, Pluto’s other moons.
Estimated to only be 8-21 miles wide, the tiny little rock is the smallest one to have been found orbiting Pluto. All the other moons orbiting Pluto are at least twice as large. Charon, the largest, is 648 miles across.
Astronomers anxiously wait for the day when the New Horizons spacecraft reaches the Pluto system in 2015. Launched in 2006, New Horizons is outfitted with a visible and infrared imager/spectrometer, an ultraviolet imaging spectrometer, a radio science experiment to measure atmospheric temperature and composition, a telescopic camera, a solar wind and plasma spectrometer, an energetic particle spectrometer, and a dust counter to measure how much dust New Horizons on its way to Pluto.
Credit: NASA. Image credit: NASA, ESA, and M. Showalter.