This image of an active volcanic eruption was taken on February 22, 2000 while NASA's Galileo spacecraft flew past Jupiter's moon Io during its 27th orbit of the huge planet. The image shows Tvashtar Catena, a chain of giant volcanic calderas, centered at 60 degrees north, 120 degrees west. Tvashtar was the location of an energetic eruption last November that was caught in action during orbit 25. A dark, "L" shaped lava flow to the left of the center in this more recent image marks the location of the November eruption. White and orange areas on the left side of the picture show newly erupted hot lava, seen in this false color image because of infrared emission. The two small bright spots are sites where molten rock is exposed to the surface at the toes of lava flows. The larger orange and yellow ribbon is a cooling lava flow that is more than more than 60 kilometers (37 miles) long. Dark, diffuse deposits surrounding the active lava flows were not there during the November 1999 flyby of Io.

This color mosaic was created by combining images taken in the near-infrared, clear, and violet filters from Galileo's camera. This range of wavelengths is slightly more than that of the human eye. The mosaic has been processed to enhance subtle color variations. The bright orange, yellow, and white areas at the left of the mosaic use images in two more infrared filters to show temperature variations, orange being the coolest and white the hottest material. This picture is about 250 kilometers (155 miles) across. North is towards the top, and illumination is from the West (left).

Image produced by: Paul Geissler, Planetary Image Research Lab. (PIRL), Lunar and Planetary Lab. (LPL), University of Arizona

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/images/io/ioimages.html.

NASA's Planetary Photojournal PIA-02550

May 31, 2000