Around 70,000 years ago, the Earth was rocked by the largest volcanic eruption to have occurred in the past 2 million years. Over what was probably a two-week span, thousands of cubic kilometers of debris spewed from Toba Caldera on northern Sumatra. This image of Toba Caldera was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite on January 28, 2006. Credit: NASA/GSFC/MITI/ERSDAC/JAROS, and the U.S./Japan ASTER Science Team