April 2, 2007 - Lo is the most volcanically active body in the Solar System. Volcanoes erupt massive volumes of silicate lava, sulphur and sulphur dioxide, constantly changing Io's appearance. This new basemap of Jupiter's moon Io was produced by combining the best images from both the Voyager 1 and Galileo Missions. Because this mosaic is made up of images taken at various local times of day, care must be taken to note the solar illumination direction when deciding whether topographic features display positive or negative relief. In general, the illumination is from the west over longitudes 40 to 270 W, and from the east over longitudes 270 W to 40 W. Color information was later superimposed from Galileo low phase angle violet, green, and near-infrared (756 nanometer wavelength) images. The true colors that would be visible to the eye are similar but much more muted than shown here. This mosaic is in an equal area cylindrical map projection, centered onlongitude 180, with grid lines at 30 degree intervals.
