Field notes about a strange aurora (IMAGE) University of Iowa Caption Notes written by David Knudsen, a physicist at the University of Calgary, in 2002 make mention of a "pulsating 'black out' diffuse glow, which then fills in over several seconds." Two decades later, University of Iowa physicists describe the phenomenon, in which patches of the background glow are blotted out, then suddenly intensify and reappear. Credit David Knudsen, University of Calgary Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.