Mount Etna, Europe's most active volcano, continues to spill rivers of lava following a July 17 eruption. The recent activity of the 3,315-meter (10,876-foot) high volcano can be seen in two images taken Sunday, July 29 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA's Terra spacecraft.

One image shows the lava advancing toward the town of Nicolosi on the Italian island of Sicily. While the last two days have been relatively calm, a river of lava is about 4 kilometers (2.5 miles) away from the town. Thick ash clouds caused airport closures and forced residents in the nearby city of Catania to use umbrellas while walking outside. The other image shows a large sulfur dioxide plume coming from the summit of the volcano.

This image shows advancing lava flows on the southern flank of Mt. Etna, above the town of Nicolosi on the Italian island of Sicily. The eruption started July 17 and might threaten the town if its magnitude increases. Also visible are glowing summit craters above the main lava flows and a small fissure eruption. The bright, puffy clouds were formed from water vapor released during the eruption. The image, acquired on July 29 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer, covers an area of 24 by 30 kilometers (about 15 by 19 miles). Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team Credit: NASA/GSFC/LaRC/JPL

The Terra spacecraft, the flagship of a fleet of satellites dedicated to understanding our global environment, is part of NASA's Earth Sciences Enterprise, a long-term research program dedicated to understanding how human-induced and natural changes affect our world. JPL is managed by the California Institute of Technology in Pasadena.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The primary goal of the mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, the radiometer will provide the capability for repeat coverage of changing areas on Earth's surface.

The broad spectral coverage and high spectral resolution of the radiometer will provide scientists in numerous disciplines with critical information for surface mapping and monitoring dynamic conditions and temporal change.

This image shows a large sulfur dioxide plume (in purple) originating from the summit of Mt. Etna and drifting southeast over the city of Catania, on the Italian island of Sicily. The eruption started July 17. The instrument's unique combination of high spatial resolution and multiple channels of thermal infrared data allow detailed mapping of the thickness and position of the sulfur dioxide plume. The image covers an area of 52 by 65 kilometers (about 32 by 40 miles). Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team