ATMOSPHERIC PEARL:

ATMOSPHERIC PEARL: Sky watcher Guillaume Poulin of Quebec has a strange story to tell: "When I went to my car after work tonight (Dec. 8th), I looked up at the sky, as usual, and I saw something very weird around the moon. With the cold climate here, ice halos are common, but this was the first time I've ever seen an egg-shaped halo." He had a camera and snapped this picture:

Even atmospheric optics expert Les Cowley was impressed: "Some halos are exceptionally rare, some are mysteries -- this one is both. It is an 'elliptical halo' and we don't understand how it formed."

"Plate or column shaped ice crystals make most halos but a few halos come from pyramid shapes," he explains. "Using a computer, we try to simulate elliptical halos using very flat discus-like double pyramids but the simulations are never quite right--compare this simulation with the image. Such flattened pyramid crystals are also wildly improbable. Guillaume's rare pearl is going to help us better understand these mysteries.