Awesomely weird expanding halo of light seen from Hawaii

The footage is from a webcam mounted outside the CFHT astronomical observatory in Hawaii (another view of it from a different webcam can be found here; sadly, both webcams are on Mauna Kea, not Haleakala). You see some stars and the horizon, then suddenly an ethereal pale arc pops into view. It rapidly expands into a thin circular shell, then fades away as it fills the view. The whole thing takes a few minutes to expand; you can see the stars moving during the event (some of the pixels on the webcam are very sensitive and make stationary "hot spots" in the field of view).


[link to blogs.discovermagazine.com]