The second-outward of Jupiter's four major moons, Europa is covered with ice, as confirmed in views from modern telescopes and the thousands of images returned by NASA's Voyager and Galileo missions. But these higher-resolution views also showed that the ice is anything but smooth. In fact, Europa's surface is covered with vast criss-crossing systems of mountain-sized ridges, jumbled regions of seemingly chaotic terrain, and patches that suggest upwellings of new surface materials from below. How scientists think about the underlying forces that shaped this incredibly complex, bizarre, and beautiful surface is the subject of this book.