File:Io volcanic hotspots.jpg

English: The left frame of this image shows various volcanic hot spots and auroral emissions on the dark side of Jupiter's moon Io, taken by NASA's Galileo spacecraft while Io was in Jupiter's shadow. The right frame is a daylight mosaic of the same surface features of Io taken in 1979 by the Voyager spacecraft, using an identical scale and projection to more easily identify locations. Grid marks are at 30 degree intervals of latitude and longitude, with north at the top. The image was taken at a distance of 1,035,000 kilometers (about 643,000 miles). In the nighttime shot, the red spots (and perhaps some of the green areas) are from volcanic hot spots with temperatures of more than 700 kelvin (about 1000 degrees Fahrenheit). Greenish areas seen near the edge of the moon are likely the result of auroral or airglow emissions of neutral oxygen or sulfur atoms in volcanic plumes and in Io's patchy atmosphere.