Pluto's other moons are Charon, Nix, Hydra and P4. Charon is by far the largest, measuring 648 miles (1,043 kilometers) across. Nix and Hydra range between 20 and 70 miles (32 to 113 km) wide, while P4 is thought to be 8 to 21 miles (13 to 34 km) across.
concern about hazards is going up," he added, referring to the collision risk New Horizons will face when it cruises by Pluto in a few years
provisionally named S/2012 (134340) 1, though it's also going by the moniker P5
P5 appears to be irregularly shaped, with a diameter between 6 and 15 miles (10 to 24 km). It zips around Pluto at an average distance of 29,000 miles (47,000 km
Charon was first spotted in 1978, 48 years after the discovery of Pluto. Nix and Hydra were found by Hubble in 2005
Pluto orbits 3.65 billion miles (5.87 billion km) from the sun on average, about 39 times farther away than Earth does
The inventory of the Pluto system we're taking now with Hubble will help the New Horizons team design a safer trajectory for the spacecraft