Three faces of Io
This picturesque series shows three views of Jupiter’s volcanic moon, Io. Taken by NASA’s now-retired spacecraft Galileo, the bottom images have been touched up with enhanced color to highlight details on the surface.

With a mass one-and-a-half times that of Earth, Io might seem diminutive in comparison to giant Jupiter. But what it lacks in size it makes up for in soul -- Io is one of the most volcanic bodies in the universe and has mountains as tall as 52,000 feet (far taller than Everest, which peaks at 29,035 feet).

Scientists think the red areas might be the deposits left behind by erupting volcanic plumes. The frosty white patches (highlighted in the bottom series) don’t show snow or ice -- there is no evidence of water on Io -- but frozen sulfur dioxide. NASA