Almost exactly a year after it spotted a fourth moon orbiting the icy dwarf planet, the Hubble Space Telescope has detected a fifth one.
A tiny new moon has been discovered orbiting Pluto, scientists announced today (July 11).
Researchers using NASA's Hubble Space Telescope found the moon, bringing the number of known Pluto satellites to five. The discovery comes almost exactly one year after Hubble spotted Pluto's fourth moon, a tiny body currently called P4.
"Just announced: Pluto has some company -- We've discovered a 5th moon using the Hubble Space Telescope!" Alan Stern, of the Southwest Research Institute in Boulder, Colo., announced via the Twitter social networking website today.
Stern is principal investigator of NASA's New Horizons spacecraft, which is scheduled to fly by the Pluto system in 2015. It will be the first mission ever to visit the dwarf planet.
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.
The new moon looks a lot more like P4 than like Charon.
"It's smaller than P4," Stern told SPACE.com.