A pine pollen corona in Kuusamo, Finland. (Photo: Mika-Pekka Markkanen/CC BY-SA 4.0)
The whole world may look forward to spring, but pretty much no one is excited for the attendant pollen explosion. Spring means new life and cold drinks and sunshine. Pollen just means itchy eyes and a fine layer of yellow on all your lawn furniture.
But if you're in the right place at the right time, all that sneezy plant dust can turn into something beautiful: a pollen corona! Thanks to a property of light called diffraction—when light waves bend around the tiny objects in their way—having lots of pollen in the atmosphere sometimes sends multicolored rings of light gently emanating from the sun or moon.
Another corona, peeking out from the side of a building. (Photo: Janne/CC BY-SA 2.0)
Ordinary, circular halos, which are caused by water droplets in the atmosphere, also work by diffraction. But because pollen grains are elongated, pollen coronas are, too. They tend to appear as multi-layered elliptical rings, cinched tight around the celestial body in question. As Bob King explains at Universe Today, the best way to see a pollen corona is to block out the sun (or moon) itself with a tree trunk and look for the glowing aura around it.
Right now, pollen corona season is full-fledged in Finland, says photographer Vesa Vauhkonen over at Spaceweather.com. But coronas can be found wherever pines, birch, spruces and alders have decided to let loose. So next time you screw your eyes closed in itchy discomfort, take a moment to look at the sun first. You might see something nice before you sneeze.
Every day, we track down a fleeting wonder—something amazing that's only happening right now. Have a tip for us? Tell us about it! Send your temporary miracles to cara@atlasobscura.com.