up:: Astronomy
Green flashes
Green flashes are real (not illusory) phenomena seen at sunrise and sunset, when some part of the Sun suddenly changes color (at sunset, from red or orange to green or blue). The word “flash” refers to the sudden appearance and brief duration of this green color, which usually lasts only a second or two at moderate latitudes. These pages illustrate and explain green flashes, offer advice for seeing and photographing them, and provide information about other refraction phenomena, such as mirages.