Hubble Telescope Finds Adorably Tiny Fourth Moon Orbiting Pluto
Pluto's New Moon NASA Peering at Pluto in preparations for a satellite visit in 2015, the Hubble Space Telescope has spotted a fourth moon orbiting the dwarf planet. The wee moon doesn't even have a name yet - it's called P4 for now - and its estimated diameter is between 8 and 21 miles. That's right, Hubble spotted something the size of a city from a distance of more than 3 billion miles away. Pluto's new moon is smaller than the dwarf planet's other companions; the big one, Charon, is 648 miles across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter, according to NASA. Hubble discovered those moons back in 2005. P4 is located between the orbits of Nix and Hydra. Hubble's Wide Field Camera 3 ultraviolet visible instrument, which was installed on the telescope's final servicing mission two years ago,...