Featured on the National Geographic News Ice formations known locally as penitents—after spiked hats warn by the Nazarenos Christian brotherhood (picture)—glow by night in Chile's high-altitude Atacama Desert. The formations are thought to form when snowpack heats unevenly and sublimates—converting directly from solid ice to gas—in patches, leaving behind blades up to about 16 feet (five meters) tall. From Monica Corcoran, National geographic senior photo editor "I love photos that make me question what I'm seeing. Are these ice formations on Mars or salt sculptures in a desert? Shooting this stark landscape by the light of the moon gives the photo an otherworldly aura."