Astronomy Picture of the Day

Explanation: Have you ever seen a moonbow? Just as rainbows are lit by the Sun, moonbows are lit by the Moon. Since the Sun is so much brighter than the Moon, sunlit rainbows are much brighter and more commonly seen than moonbows. The above movie captures not only a moonbow, but several rainbows, moving clouds, and the starry sky visible in 2009 February over Patagonia in Chile. The slight movement of the rainbows is due to the changing sky position of the Sun. Since moonlight is itself reflected sunlight, the colours are nearly the same. Both rainbows and moonbows are created by light being scattered inside small water droplets, typically from a nearby rainfall. The raindrops each act as miniature prisms, together creating the picturesque spectrum of colours seen.