Hubble discovers a fifth moon orbiting Pluto

This image, taken by NASA's Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto.

The green circle marks the newly discovered moon, designated P5, as photographed by Hubble's Wide Field Camera 3 on July 7.

Other observations that collectively show the moon's orbital motion were taken on 26, 27, 29 June and 9 July, 2012.

The moon is estimated to be 9 to 25 kilometres across. It is in a 93 000-kilometre-diameter circular orbit around Pluto that is assumed to be co-planar with the other satellites in the system.

The observations will help scientists in their planning for the July 2015 flyby of Pluto by NASA's New Horizons spacecraft.