Man captures photograph of the Sun flashing green in incredibly rare optical illusion

As a photographer, there must be the odd occasion when you sit back after taking a shot and just know you got it.

That has to have been something that happened to Craig Hayslip, a research assistant at Oregon State University, when he recently photographed a sunset in Bandon, Oregon.

He uploaded a couple of photos to his Instagram page on April 21, and while the first is a really nice shot, it's one that you've probably seen versions of before - but the second is a far rarer.

It captures an optical illusion known as the green flash. This sometimes occurs at the very start of a sunrise or the very end of a sunset, just as the Sun appears or disappears behind the horizon.

If it does happen, it lasts no more than a couple of seconds, and creates a stunning flash of green light that is a pretty dazzling sight to behold.

This is caused by the way the Sun's light hits the Earth's atmosphere, at just the right angle to be refracted through a prism and come out as this amazing blaze of color.

If that was all it took, though, green flash would happen regularly - but instead, there are more detailed requirements, including the need for atmospheric temperatures where the air higher in the sky actually gets warmer.

This is most often the case above bodies of water, so the green flash has often been sighted on coastlines or over the ocean.

Finally, that green color is explained by the way the electromagnetic spectrum refracts - blue and green tend to refract more strongly than warmer colors like red and yellow.

Hayslip didn't exactly make a big deal out of his incredible photograph, but it's a bit of a bucket list event for some meteorologists and skywatchers.

Many people look out for it their whole lives and only see it on a handful of occasions, so if you're ever watching a nice sunset by the beach or overlooking the sea, it's worth paying attention to see if you can glimpse a green flash of your own. Of course, always be wary to not look straight at the Sun without proper eye protection.

Until then, though, you can still enjoy Hayslip's excellent photograph of the event - and unlike the recent total solar eclipse, there aren't hundreds of thousands of other photos flooding social media to compete with it.