What causes scorching hot lava to spike through Earth's crust and make a volcano blow its top? Do volcanoes exist in space? What do brave volcanologists learn by climbing right into a volcano's mouth? In the wake of the eruptions by Iceland's Eyjafjallajökull, everyone wants to know! Ten spectacular gatefolds, plus incredible photos, graphs, maps, diagrams, and first-person stories, take intrepid young explorers right to the source to find out.