The phenomenon began when what appeared to be a blue light seemed to soar up from behind a mountain. It stopped mid-air, then began to circulate.
Within seconds a giant spiral had covered the entire sky. Then a green-blue beam of light shot out from its centre - lasting for ten to twelve minutes before disappearing completely.
Russia denied any missile tests in the area. Link to story. Link to photo gallery. -via Metafilter
(image credit: Svein-Egil Haugen)