Strange Glowing Clouds over the Night Sky

The idea of glowing clouds moving across the sky at night isn't something you see every day.

An article on Wired.com reports that sky watchers across the globe have been capturing images of the strange phenomenon. It may be a natural occurrence by the sun's rays or something more concerning. Noctilucent ("night shining") clouds moving across the night sky were first documented by an amateur astronomer in 1885. The clouds are made from polar ice crystals in the air that are illuminated by the position of sunlight when the sun is below the horizon. Some believe it could be man-made due to global warming.