An Exquisitely Rare Pollen Corona

Coronas are colorful halos around the sun or moon. They are generally caused by ice crystals or water droplets. Under special conditions, they may also be formed by pollen. Since 1997 I have observed, measured and photographed coronas caused by pollen from juniper trees (Juniperus asheii) in the Texas Hill Country. They appear only a few times each winter at most and are visible only on clear days. This one occurred at noon on 27 January 2007. I have described pollen coronas in "Solar corona caused by juniper pollen in Texas," Applied Optics 37, 1486-1488, 20 March 1998.

CAUTION: Your camera and eyes can be damaged by directly viewing the sun! For tips on photographing a pollen corona, see www.sunandsky.org and click on "Sky Photos."

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• corona
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• fmims

[matysek123456]

You should look for pollen in a spring series. In May cover the sun with a building or somekind of pole and look to a sun with your sun glasses on, if the pollen already started to grow in forests, you should see this corona.

[phyzome]

How can you tell that it's a pollen corona? Do you look for a certain "signature" of arcs and dots?