From Spaceweather.com May 15, 2008:
It begins with a sneeze. Pollen floating through the air tickles your nose, and your body responds by expelling the allergen. Gesundheit!
That's German for "look at the sun." Not really, but look anyway. The same pollen that makes you sneeze can also make beautiful coronas around the sun.
See http://spaceweather.com/ for photos
"Coronas are produced when light waves scatter from the outsides of small particles," says atmospheric optics expert Les Cowley. "Tiny droplets of water in clouds make most coronas, but opaque equal-sized pollen grains do even better. They make small but very colorful multi-ringed coronas."
"Unlike water droplets, pollens are non-spherical--and this adds to their magic," he continues. "Many have air sacs to help carry them in the wind. These align the grains to give beautiful elliptical coronas with bright spots." This is why Nitze's pollen corona looks the way it does.
"So, the next time you sneeze..." Gesundheit! "...look for coronas near the sun."
more images: from Eva Seidenfaden of Trier, Germany