A pollen corona over Helsinki, Finland, in June 1994. This corona was caused by pine pollen, individual pollen particles of which look a lot like Mickey Mouse heads. Due to this particle shape, the corona is not symmetric but has several brightenings. The third ring is only faintly visible in this image, but in the original slide it is quite clear. This photo was taken in the beginning of June, when pine pollen is abundant in the air of southern Finland. Pollen coronas are not rare, although they have been identified as an individual phenomenon only a few years ago.

(© Timo Nousiainen)