Cumberland Falls Moonbow — Kentucky

On clear nights around the full moon, visitors to Cumberland Falls gather along the viewing area above the gorge to witness one of Earth's rarest optical phenomena: a moonbow. As moonlight refracts through the mist rising from the 20-metre-wide, 12-metre-high curtain of falling water, a faint arc of pale colour materialises in the darkness below. To the naked eye it appears as a ghostly white or softly tinted arch; with a camera set to long exposure, rich bands of colour bloom across the frame. The thunderous sound of the falls surrounds you, and cool mist drifts across the overlooks, making the air feel alive. The falls flow through Daniel Boone National Forest year-round, so even the hike to the overlook passes through genuine old-growth forest. The moonbow recurs predictably each lunar cycle, giving visitors a reliable celestial calendar to plan around — a rarity among natural wonders.