Airglow, Milky Way over Black Canyon
Black Canyon of the Gunnison National Park, Colorado, 2014
The green color of the sky in this image is not a Photoshop enhancement or sleight-of-hand. Instead, it is a phenomenon referred to as airglow, which can arise from a number of chemical and physical processes in the upper atmosphere. Though it is sometimes visible to the naked eye, I had no idea it was present until after making my exposures. I made this image from the Kneeling Camel viewpoint on the North Rim of Black Canyon; the bright light on the right side of the frame is from the visitors center on the South Rim. Photo © copyright by Greg Owens.