One day many years ago, I visited a southern New Jersey beach and watched the Sun set. The sand glowed with a warm gold. A vast expanse of Delaware Bay spread before me with crimson-tinged waves. The huge, flattened globe of the Sun had dimmed enough for me to look straight at it as its bottom edge touched the distant horizon.

I was filled with the grandeur of the scene, thrilled to watch as that fiery globe sank from view — going . . . going . . . almost gone. Suddenly the loveliness was pierced by a blast of stronger beauty so intense that it left my jaw hanging. For just a second or two, the last tiny piece of Sun gleamed a vivid green. I shouted in surprise and joy on the empty shore. I had just seen the legendary green flash.

While people often tell me about their sightings of meteors or halos around the Moon, hardly anyone reports seeing the green flash. Why haven’t more people witnessed this astonishing phenomenon? The biggest impediment has been misinformation. Many sources claim that the green flash is very rare, or only visible in the tropics, or seen only at sunsets over the ocean.

In reality, mild versions of the green flash are not uncommon in most climates, and even its most spectacular forms don’t necessarily require a sea horizon to observe. Furthermore, the phenomenon only rarely appears as a flash. Far more often you’d see a rapid coloration of the last tiny blip of Sun as it sets.

Literary Beginnings

The green flash didn’t gain public attention until 1882, when it appeared as an important topic in the Jules Verne novel Le Rayon Vert — “The Green Ray,” as the phenomenon is sometimes known. Verne waxes floridly poetic about the color of the flash, describing it as “a most wonderful green, a green which no artist could obtain on his palette, a green of which neither the varied tints of vegetation nor the shades of the most limpid sea could ever produce the like! If there is a green in Paradise, it cannot but be of this shade, which most surely is the true green of Hope.”

One of Verne’s characters also recalls a Scottish legend that claims that whoever has seen the green flash will never again err in matters of the heart. It’s a charming idea. Unfortunately, researchers have never found any trace of the legend in Scottish folklore. So it seems likely that the imaginative French author made it up himself.

A rash of green-flash sightings and speculations followed in the wake of Verne’s book. But these were often made by uncritical observers and writers. They in turn probably helped set off a skeptical — and incorrect — theory about the cause of the green flash. According to some scientists of the late 19th and early 20th centuries, the green flash did not arise in Earth’s atmosphere at all, but only in the viewer’s eyes. The green flash, they claimed, was the complementary-color afterimage created by staring too long at the bright setting Sun. You can produce this effect yourself by staring at a red object, say a ripe tomato, in a brightly lit room. After about 15 seconds, switch your gaze to a white surface and you’ll see a ghostly bluish green “anti-tomato.”