Astronomy, Physics, Volcanology
Jupiter's innermost major moon is a volcanic wonderland, dotted with more active volcanoes than anywhere else in the solar system. Io owes its volcanic success to the intense gravity exerted on it from Jupiter's other major moons and Jupiter itself. If you've ever bent a paper clip back and forth, you'll recall that it heats up. This is what's happening on Io, but on a planetary scale. Io's volcanoes put the ones on Earth the shame, creating plumes of sulfuric material that go hundreds of miles into the air. Io is the most geologically active object in the solar system, leading to slight differences in its surface every time it's viewed. PASH is pretty gung-ho for Io!