Astronomy Picture of the Day

Explanation: What is it? Some surely natural phenomenon has appeared in a video that, so far, has defied clear identification. The above time-lapse video was made to record Perseid meteors above Hopewell Rocks in New Brunswick, Canada late this summer. The video, which ran from 9:30 pm August 11 to 3:00 am the next morning, records several meteor and satellite streaks beyond a picturesque background. Each image records a 30 second exposure. At about 25 seconds into the video, however, an unusual patchy green glow appears to cover the sky. Possible explanations include airglow, aurora, lighting from an artificial or natural source, or something completely different. This APOD is an attempt not only to solve this intriguing sky riddle, but to measure how powerful the APOD readership is as a citizen-science, collective-intelligence engine. If you have insight into what might be causing this phenomenon, please contribute to the discussion.