![Moons: Active Worlds](http://stsci-opo.org/STScI-01EVSVDD3091GDJHV85GBE3A9F.png)
Discover the makeup of four active Solar System moons, worlds unto themselves with unique, dynamic environments. The ice worlds of Europa and Enceladus can be compared and contrasted with methane-rich Titan and fiery Io. How similar or different is each moon from our own active world, Earth?
Credits
Image
NASA, Joseph Olmsted (STScI)