The discussion will take place at a special Web chat area made just for this purpose. To participate on that night, you need only to have a forms-capable Web browser. Please join us with some well thought-out questions. Io's surface is covered with volcanic deposits that are thought to contain ordinary silicate rock, along with various sulfur-rich compounds that give the satellite its distinctive color. In the brighter areas the surface is coated with frosts of sulfur dioxide.
Dark areas are regions of current or recent volcanic activity.
Planetary scientists say many changes are evident in the surface markings since this region of Io was imaged 17 years ago by the Voyager spacecraft. The bright regions near the eastern limb of the moon are much more prominent in the Galileo images than they were previously. Masubi was discovered as an active volcano during the Voyager encounters of Io in 1979. PDT June 27. Initial observations of the Io plasma tours by the ultraviolet experiment are complete and the first remote observations of Io by the camera were done today.