Just in time for St. Patrick's Day 2013, a cloud of charged particles originating from the sun hit Earth's magnetic field, sparking a geomagnetic storm that generated an amazing round of colorful auroras across the skies of many northern countries.

Northern lights are created when charged particles are flung off the surface of the sun, travel to Earth, and get funneled down to the poles along magnetic field lines. The particles collide with molecules in our atmosphere, transferring energy and making the air molecules glow like a neon sign. (Learn more about auroras.)—Andrew Fazekas