The flash only lasts for two seconds.
A man has shared the moment the sun appeared to flash green moments after it had set.
Craig Hayslip, a research assistant at Oregon State University, caught the moment on camera in Bandon, Oregon, a few days ago.
He was just 15 miles west of Coos Bay when he not only spotted the incredibly rare optical illusion, but managed to take pictures of it as well.
The green flash is another example of an optical phenomenon that sometimes occurs around the moment of sunset or sunrise. It lasts for no longer than two seconds.
So, what is it exactly, and how can you spot it yourself?
The flash occurs when the Earth’s atmosphere causes light from the Sun to separate, or refract.
As the sun’s light, which appears pure white, passes through a prism, the light refracts and creates a stunning flash that is visible to the human eye.
However, the flashes only happen at certain temperatures when air at high altitude becomes warmer, meaning the flash is more likely to be spotted over water than on land.
The green colour is produced by the atmospheric refraction of light, which causes objects near the horizon to appear slightly higher in the sky than they actually are.
Refraction is stronger for blue and green light than it is for yellow and red light, which leads to a bluish or greenish hue on the upper side of the sun.
The flash lasts for around two seconds and is extremely rare to see.
Space.com’s skywatching columnist, Joe Rao, said he has been ‘an avid skywatcher for over half a century’ – but despite looking for the green aura on many different occasions, he has definitively spotted it just twice.
For those hoping to catch a glimpse of green flash, a few tips and tricks can help.
Generally speaking, the flash appears more on the coast than on land, so getting to a low horizon level will increase your chances.
Cooler weather and the absence of red tints in the sky will help, with reports citing that when the horizon seemed to have a bright white or yellowish glow.
It should be noted that you should avoid the sun’s gaze until the last moment to minimise your risk of eye damage.
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