Europa's Icy Jigsaw Puzzle Solved

Ever since NASA’s two Voyager spacecraft snapped the first photos of icy cracks crisscrossing Jupiter’s moon Europa in 1979, astronomers have speculated that tectonic forces could be at work. But the first solid evidence didn’t arrive until September, when a team of planetary geologists announced it might have solved the mystery by treating the moon’s crust like a jigsaw puzzle.