Figure 1, Visible and Near-Infrared (VNIR)
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Popocatepetl, Mexico's most active volcano, erupted on February 23, sending blocks and bombs down the volcano's flanks, and emitting an ash column 1 km above the summit. Two days later, an ash cloud was still seen coming from the volcano. The thermal infrared color composite reveals a hot spot (red) at the summit crater. The dark red color near the vent of the east-blowing ash cloud suggests that its composition is dominantly ash material; further downwind, the color changes to purple, suggesting that some of the ash particles may be ice-covered. The images were acquired February 25, 2020, cover an area of 18 by 22.5 km, and are located at 19 degrees north, 98.6 degrees west.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 50 to 300 feet (15 to 90 meters), 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 in Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington.

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