Pollen Coronae ~ Imaged by Sergei Antipov near Murom, some 100km from Nizhny Novgorod, Russia. Pollen in the air were many varieties of pine, apple, cherry, acacia, lilac and mountain ashes among others.  All images ©Sergei Antipov
Often pollen grains, for example pine, have air sacs to assist wind dispersal. The sacs align the grains and this gives rise to the oval coronae and bright spots. A horizontally elongated object gives a vertically elongated corona.

The coronal pattern is extensive as Sergei's strongly enhanced version shows at right.

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Pollen coronae are characteristically small and vertically elongated. Sometimes they have brighter areas or spots on the rings. Pollen grains diffract sun or moonlight to produce the pattern in the sky. When one particular pollen type is abundant then there can be many rings as all the grains are of the same size.