Elliptical Corona

December 18, 2008


Photographer: John A. Adam, Old Dominion University
Summary Author: John A. Adam

My flight from Calgary, Alberta was approaching Houston, Texas when I noticed this beautiful corona as the plane turned towards its final descent. What caused it? The image of the Sun on the engine housing, viewed through a layer of tiny water droplets on one of the inner window surfaces! The Sun’s reflection appeared elliptical because of the curvature of the metallic surface, and the light from that source was diffracted by the tiny droplets (causing the observed interference pattern), resulting in this elliptical spectrum of colors around the reflected source. The mistiness did not cover all of the window -- notice that the corona at left is incomplete. Photograph taken on an afternoon in late June 2008.