March 05, 2007
This exquisite nighttime sundog or paraselene was photographed in Brannenburg, Inntal, Germany on June 10, 2006. Most lunar halo phenomena go unobserved because they're usually quite faint, but this paraselene was wonderfully gaudy. They're generated by plate-shaped hexagonal ice prisms, which when falling undisturbed, automatically orient themselves in a horizontal position. Moonlight (or sunlight) enters one of the side faces of the prism and exits the alternate one.