Pollen Corona and Solar Pillar

Photographer: John Stetson
Summary Author: Jim Foster, John Stetson

As shown in the inset above, A. Groff, R. Miller, and I imaged some of the pine pollen that covered nearly all of Maine in mid June of 2008. Pollen grains diffract sunlight, and if enough grains are aloft, a corona such as the one above may be observed (the orange concentric rings around the Sun). Horizontally stacked, hexagonal ice crystals in the atmosphere are responsible for the solar pillar. On occasion, plate-shaped crystals are arranged so that they reflect sunlight (in the form of vertical shafts) toward the viewer. Photo taken on June 12, 2008.