This image shows the Chaac region, on Jupiter's moon Io, viewed by two instruments on NASA's spacecraft Galileo during the flyby on February 22, 2000. On the left is an image taken by Galileo's onboard camera. On the right is a map of the relative abundance of sulphur dioxide obtained from an observation made by the infrared spectrometer, an instrument onboard Galileo. The right map shows that the bright white material inside the small caldera just to the east of Chaac (lower right in the camera image) is filled by sulphur dioxide. This sulphur dioxide is purer than at any other location so far observed on Io. It may represent a frozen layer of sulphur dioxide ice on the floor of the caldera. The width of the image seen on the right map is about 100 kilometers (62 miles).

The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.

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://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.