What Has a Volcano Done for You Lately?

Volcanoes are common in the solar system. Remnants of ancient lava flows are plentiful on Mercury and Venus. Our moon has large "seas" (maria) of solidified lava. Mars has the largest extinct volcano known in the solar system, Olympus Mons -- a single volcano as big across as Arizona. Beyond Jupiter, evidence of cryovolcanic activity has been detected on some of Saturn's icy satellites, especially Enceladus, which erupts salty ice water out of over 100 fissures at its south pole. Saturn's Ti...