From the ground, the lava lakes on Vanuatu's Ambrym volcano look something like J.R.R. Tolkien's Mount Doom. Roiling pools of lava glow a deep orange, spewing lava and seemingly endless plumes of steam and gas.
From space, the view is more subtle. The Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite captured this natural-color image of Ambrym's caldera on Dec. 13, 2012. Twin lava lakes on Ambrym's Marum cone are visible. The larger of the two, which is gray, lies within Mbuelesu crater; to the southwest, Mbuelesu has a secondary crater that contains a pinkish-gray lava lake.
Active lava lakes often have a partly solid, shiny gray crust that forms as the atmosphere cools their surfaces. The crust is rarely more than 5 to 30 centimeters (2 to 12 inches) thick and usually lasts just a few hours because it continually circulates, breaks and sinks into the molten lava below. The pink color of the smaller lake suggests that surface was especially agitated and the crust was absent or in the process of sinking back into the lake.
Image courtesy of NASA Earth Observatory, the NASA EO-1 team and the U.S. Geological Survey.