#PPOD: When the Sun, Moon, and Earth align just right, moonlight meets the mist at the base of a great waterfall. The result is a moonbow: a rainbow born not of daylight, but of reflected lunar light. The aurora borealis follows a similar logic, though its source is far more violent. Charged particles from geomagnetic storms race toward Earth, guided by magnetic fields into the upper atmosphere, where they excite atoms into glowing pillars of light. Credit: Josh Dury
