The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft captured this pair of images of Iceland's Eyjafyallajökull volcano on May 3, 2010. They are displayed at 90 meters (approximately 300 feet) spatial resolution. On this day, Ireland closed its airspace for several hours due to presence of ash over the country.

The left-hand image is a color-composite of data from the ASTER visible and near-infrared bands. The eruption plume and drifting veil of ash are dark grey, streaming towards the east. The image shows an area of 42 by 44 kilometers (25 by 27 miles).

The right-hand image is a color-composite of data from three of the ASTER thermal infrared bands. The plume appears purple in color, indicating that it dominantly contains ash, and very little sulfur dioxide. The bright feature at the start of the plume is the incandescent lava flow produced by the eruption.

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 December 18, 1999, on NASA's 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 the 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 ASTER 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/.