The rare event captured by NASA's Solar Dynamics Observatory last July is known as "coronal rain." It starts when a solar eruption spews plasma from the surface of the sun high up into the star's atmosphere; then, as the material cools and condenses, the charged particles that make up the plasma get trapped in the star's magnetic fields, and are shuttled along the magnetic field lines back to the sun's surface. The 90,000-degree plasma lights up the strange motions and structures within the otherwise invisible magnetic fields.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.