A colorful corona forms around the Moon in a winter night of Sweden. Down on the ground is a Rune Stone with runic inscriptions dating from the early Middle Ages. These stones have been used by Vikings for centuries. There are approximately 6,000 known rune stones in Scandinavia which 3,000 of them date from the tenth and eleventh centuries and have been found in Sweden. The colors of the corona is enhanced to better show the dynamic of the atmospheric phenomenon. As described by Atmospheric Optics a corona may be seen when thin clouds partially veil the sun or moon. The first ring is bluish on the inside grading through greens and yellows to red outermost. The coronae are much smaller than the 22° halo around the Moon and the Sun. Coronae are produced by the diffraction of light by tiny cloud droplets or sometimes small ice crystals. © P-M



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