The Green Flash!
It’s not a superhero. What we’re talking about is an atmospheric phenomenon that can sometimes be seen as the sun sets. What’s going on here?
It turns out the green flash is a kind of mirage. As the sun nears the horizon, its light travels through more of the atmosphere than when it is straight overhead. The atmosphere acts like a prism, bending the different wavelengths in a rainbow-like effect. This is called atmospheric dispersion.
Shorter wavelengths, like blue and violet, bend and scatter more than longer ones, like orange and red. This is why our sunrises and sunsets tend to be orange and red.
But what about that green flash?
For just a moment, as the sun dips below the horizon, the green light that until now was being bent away from our eyes becomes visible.
The result is a greenish hue that appears just above the setting sun.
So how do you see it? First, you need a clean, clear sky. Next, you need to be able to see the sun dip all the way beneath the horizon. Basically, you need an ocean in front of you.
Just don’t look directly at the sun until it’s almost set. You don’t want to hurt your eyes, and your chances of seeing another green flash.