While volcanic eruptions and earthquakes serve as immediate reminders that Earth’s insides are anything but tranquil, there are also other, more elusive, dynamic processes happening deep down below our feet. Using information from ESA’s Swarm satellite mission, scientists have discovered a completely new type of magnetic wave that sweeps across the outermost part of Earth’s outer core every seven years. This fascinating finding, presented today at ESA’s Living Planet Symposium, opens a new window into a world we can never see.