Detail of changes east of Pele on Jupiter's moon Io as seen by NASA's Galileo spacecraft between June (left) and September (right) 1996. The caldera at the center of the images that changes from bright to dark is approximately 80 kilometers in diameter. Some scientists speculate that this brightness (albedo) change might be due to flooding of the crater floor by lava. The left frame was reprojected and stretched to match the geometry and average colors of the right frame. Before this stretch, the earlier image (left) was significantly redder than the later image (right); this may be due to variations in lighting. Both frames were created with images from the Galileo Solid State Imaging system's near-infrared (756 nm), green, and violet filters. North is to the top of both frames.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo. Image Credit: NASA/JPL