The 'Floating Hills' of Pluto (Photo)

Mini-mountains of water-ice creep across Pluto's surface, carried slowly along by the dwarf planet's nitrogen-ice glaciers, a newly released photo suggests. The image, which was captured by NASA's New Horizons spacecraft during its historic Pluto flyby last July, shows that the vast Sputnik Planum region within the dwarf planet's famous "heart" is studded with chains and clusters of water-ice hills. "Because water ice is less dense than nitrogen-dominated ice, scientists believe these water-ice