Sometimes, at sunset, the sun appears to suddenly and briefly change color. Blink, and you’ll miss it.
A green flash is a phenomenon in which part of the sun appears to suddenly change color for about 1 or 2 seconds. The brief flash of green light is seen more often at sunset than at sunrise.
This fleeting spectacle is caused by the refraction of sunlight, which is particularly significant at sunset and sunrise, when the light travels through more of the Earth’s atmosphere. The atmosphere bends the sunlight passing through it, separating the light into its different colors, much like a prism bends and splits sunlight into rainbows.