Pluto's Sunken Heart

Explanation: This shaded relief view of the region surrounding the left side of Pluto"s heart-shaped feature — informally named Sputnik Planum — shows that the vast expanse of the icy surface is on average 2 miles (3 kilometers) lower than the surrounding terrain. Angular blocks of water ice along the western edge of Sputnik Planum can be seen "floating" in the bright deposits of softer, denser solid nitrogen.

Pluto

Image credit: NASA/JHUAPL/SwRI