Three Surface Changes on Io

Two views of three areas on Jupiter's moon Io showing changes seen on June 27th, 1996 by the Galileo spacecraft as compared to views seen by the Voyager spacecraft during the 1979 flybys. Galileo images are on the right; Voyager 2 images are on the left. North is to the top. At top (latitude +33, longitude 20) is a new volcanic feature consisting of a dark spot, perhaps a caldera floor, surrounded by a diffuse circular ring of reddish material, perhaps a plume deposit. The region in the middle corresponds to a hotspot observed by Earth-based observers on June 2nd, 1996. The Galileo image reveals new dark features, perhaps lava flows, within a field of lava flows (latitude +13, longitude 359). At bottom is the region near Sengen Patera (lower dark feature in the Voyager image; latitude -32, longitude 305). The dark materials have brightened or have been buried by new bright deposits by the time of the Galileo encounter. Earth-based observations indicated a hotspot in the Sengen Patera region also on June 2, 1996. Images are all 500 km wide. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. 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 http://www.jpl.nasa.gov/galileo/sepo.