Mt. Etna, Sicily, Italy, is Europe's most active volcano. In mid-May 2016, Mt. Etna put on a display of lava fountaining, ash clouds and lava flows. Three of the four summit craters were active, with lava flows descending into the Valle del Bove to the east, and (unusually) a flow to the west. In this nighttime thermal infrared image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft, the more recent western flow is displayed in yellow, superposed on an older daytime image, with vegetation in red. The thermal data were acquired May 26, 2016, cover an area of 19 by 19 miles (30 by 36 kilometers), and are located at 37.7 degrees north, 15 degrees east.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington, D.C.

More information about ASTER is available at http://asterweb.jpl.nasa.gov/.