IO is a moon of Jupiter. This moon is about the size of our moon, but is very hot inside. It is so hot inside that sulfur erupts to it's surface. These sulfur eruptions blast 60 to 70 miles into space and last months. Much of the material falls back to IO covering up any craters that are formed. So much sulfur falls to IO that this moon is getting larger as time goes by. The reason that it is so hot inside of IO is because the powerful gravitational pull of Jupiter causes tidal stress inside this moon.
