Io. The most volcanically active body in the Solar System, it&#39;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&#39;s strong gravity and that of its companions Callisto &amp; Ganymede, Io is mercilessly squeezed, releasing heat. ©Mona Evans,&#34;Jupiter&#39;s Galilean Moons&#34; http://www.bellaonline.com/articles/art42279.aspSolar System, Giants Planets, Volcanic Eruption, Ios, Red Materials, Image, Closest Large, Volcanic Activities, Large Moon