Changes near the Volcano Loki Patera on Io

Four views of the volcano Loki Patera 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. Clockwise from upper left is a Voyager 1 high resolution image, a Voyager 1 color image, a Galileo color image, and a Voyager 2 color image. North is to the top of the picture. During the Voyager flybys large dense volcanic plumes erupting from each end of the dark linear "fissure" to the northeast of the dark caldera and plume deposits obscured much of the surrounding surface. These dark jets are not visible in the Galileo image, and other images have confirmed that the Loki plumes were inactive during this Galileo encounter. Ground-based observers have determined that the Loki hot spot, historically the most energetic on Io, has been unusually dim. The fissure appears extended and elongated to the east and southwest, perhaps also resulting in a migration of the plume vents. There is an enlarged dark spot to the west of Loki. The materials just south and northeast of the caldera appear more reddish color. Images are 894 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.