The newly discovered moon, P4, is the small satellite orbiting the dwarf planet.
P4 was first seen on June 28 with further confirmation on July 3 and July 18. It is thought that the moon may have appeared as a smudge in images of Pluto from 2006. The finding came from NASA's New Horizons mission.
NASA reports:
"I find it remarkable that Hubble's cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km)," said Mark Showalter of the SETI Institute in Mountain View, Calif., who led this observing program with Hubble.
It is estimated that P4's diameter is just 8 to 21 miles. Pluto's other moons have slightly larger diameters; Charon (648 miles), Nix and Hydra (20 to 70).
P4 is located between Nix and Hydra which were discovered by Hubble in 2005. Charon was located in 1978 at the U.S. Naval Observatory.
