How to Spot the Mythical Green Flash (Which Is Actually Very Real)
While it sounds like some kind of superhero – especially the unlicensed off-brand look that hangs in Times Square – the “green flash” is actually a real thing that you can actually see in the sky with your own eyes. And while we know that the green flash exists (there is a lot of photographic evidence ), it has taken on a more mythical status because it is not seen on a regular basis.
Unlike some meteor showers or moons, you cannot mark a green flash on your calendar: it just has to happen. But there are ways to improve your chances of catching a glimpse of the elusive show of natural light. Here’s what you need to know.
What is green flash?
The first thing to know is that, although there are several natural phenomena that are grouped together and called the “green flash”, most of them belong to one of two forms that were identified by the English physicist James Prescott Joule in 1869. The first form is what Joule called “the last glimpse,” and is a bluish-green flash that appears at the last moment before the sun sets below the horizon.
The second form is associated with imitation of a mirage and, according to Andrew T. Young, astronomer, expert in green flare and professor at San Diego State University, is mainly visible from a hill. (If you’d like to learn more about green flash, Young maintains a website full of information and photo links.)
How to catch a green flash
You don’t need any fancy equipment to see the green flash, but you do need to be in the right place at the right time. As with most exciting events in the sky, your best chance to see a green flash is in clear weather. According to an article on EarthSky, it also helps you see very distant horizons, such as the ocean or sea.
Most of the green flashes that people report are categorized as “last flashes”, occurring at sunset, at the very last second before the sun sinks below the horizon. And yes, a green flash usually lasts only one second, or maybe two (this is not called a “green continuous light”). You can also see a green flash just before sunrise, but the timing is more difficult.
The key to catching a green flash at sunset is not to drop in too early . This is important because a) if you look directly into the sun before (or at any time in fact), you can damage your eyes; and b) what makes you miss the green flash. Instead, look away until the thinnest edge of the sun is visible above the horizon.