MOONS OF JUPITER: Io

Welcome to Jupiter, the solar system's biggest planet and host to more than 63 peculiar moons -- a steady contender for moons compared to satellite-strewn Saturn.

From sulfur-spewing furnaces to ice-encrusted oceans, these Jovian satellites are anything but normal! Browse through 10 of our favorites here.

If you're looking for a fiery, volcanic spectacle, head to Io, the innermost of Jupiter's "big four" moons.

Jupiter's gravity pulls at Io so strongly that the land has tides of up to 300 feet (100 meters). This gravitational tug-of-war produces scorching heat and raises more volcanic activity here than anywhere else in the solar system.

Io has a sulfurous surface, and its volcanoes spew silicate magma, causing the hellish moon's surface look a like a pizza.

More on How Volcanoes Work at