On April 27, photographer Jeff Dai captured this stunning image of the skies over Tibet, following some powerful thunderstorms in Bangladesh. The colorful ripples of stars seem to form a luminescent spiral in a phenomenon known as "airglow." "The unusual pattern is created by atmospheric gravity waves, waves of alternating air pressure that can grow with height as the air thins," explains NASA, which selected Dai's image as its "Astronomy Picture of the Day." The light and color produced during this airglow shot are the result of a chemical reaction taking place about 90 kilometers up in the sky.