Jupiter's bright yellow Io is currently the strangest moon in our Solar System right no, and this is how it would appear in the "true colors" perceptible to the average human eye - taken in 1999 July by the Galileo spacecraft that orbited Jupiter from 1995 to 2003. Io's colors derive from sulfur and molten silicate rock. The unusual surface of Io is kept very young by its system of active volcanoes. The intense tidal gravity of Jupiter stretches Io and damps wobbles caused by Jupiter's other Galilean moons. Continue reading for more.