This image, taken by the NASA/ESA Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto. The green circle marks the newly discovered moon, designated S/2012 (134340) 1, or P5, as photographed by Hubble’s Wide Field Camera 3 on July 7, 2012.

Researchers have discovered Pluto has another moon.

The former planet's fifth moon is 10-25 km across and appears as a speck of light in images from the Hubble telescope.

"The moons form a series of neatly nested orbits, a bit like Russian dolls," Mark Showalter of the SETI Institute in Mountain View, Calif., said in a release about the finding Wednesday.

Pluto's largest moon, Charon, was discovered in 1978. Hubble observations in 2006 uncovered two additional small moons, Nix and Hydra. In 2011 another moon, known as P4, was found in Hubble data.

This new moon has been named S/2012 (134340) 1, or P5, for now.