Io. The most volcanically active body in the Solar System, it's about the same size as the Moon and orbits at about the same distance from Jupiter as the Moon does from Earth. Yet it has over 400 volcanoes and a “month” on Io lasts only 42 hours. This is all down to gravity. Caught between Jupiter's strong gravity and that of its companions Callisto & Ganymede, Io is mercilessly squeezed, releasing heat. ©Mona Evans,"Jupiter's Galilean Moons" http://www.bellaonline.com/articles/art42279.asp Volcanic Erupting, Solar System, Average Moon, Red Materials, Galileo Spacecraft, Volcanic Activities, Giant Planets, Outer Spaces, Large Moon
Jupiter and Io. "The image shows a major eruption in progress on Io's night side, at the northern volcano Tvashtar. Incandescent lava glows red beneath a high volcanic plume, whose uppermost portions are illuminated by sunlight. The plume appears blue due to scattering of light by small particles in the plume."