Sizzling Io

What's cooking on Io ? This active moon of Jupiter is marked with volcanoes spewing lava that is now known to be hotter than any lava on Earth . Above is the highest resolution color-enhanced image yet composed of the most active surface in our Solar System . Features as small as three kilometers are visible. Sulfur compounds cause many of Io 's unusual colors, while darker regions are probably composed of silicate rock .