Ever since the late Sarasota mystery writer John D. MacDonald wrote A Flash of Green in 1962, locals and visitors stand on the beach at sunset, hoping to see a brief burst of green light just as the sun sinks into the Gulf. In MacDonald’s tale about greedy developers destroying the environment in a small Florida town, the flash of green refers less to the elusive atmospheric event than to the corrupting allure of money. One old-timer in the novel scoffs at the idea that the flash of green even exists.

“It stands to reason, mister, any damn fool stares into the sun long enough, he’ll end up seeing exactly what some other damn fool tells him he’s going to see,” he declares.

But scientists—and many Sarasota sunset-watchers—say the flash of green is real.

According to livescience.com, the brief phenomenon results from the refraction of sunlight, and it can happen at sunrise or sunset. At those times, light must travel through a large expanse of the atmosphere, and as it travels, it bends and separates into its different colors. Blue and violet lights, which have shorter wavelengths, refract strongly and are scattered by the atmosphere. Red, orange and yellow are absorbed and disappear, leaving only the green light visible during those fleeting seconds when the sun dips into the sea.

And that’s one more reason to drop what you’re doing and head to the beach at sunset.