The flash you see
– or don’t
You either swear it exists and you’ve seen it or you don’t and
you think everyone who has just may be crazy. It’s the green
flash.
I suffered a little gentle derision about this little-known
phenomenon last week, when a few of us were bobbing along waiting
for the breeze to freshen off Santa Cruz.
About a month earlier, I’d mentioned the green flash, and that
night my wife even saw it. Since we could not observe it last week,
my sanity is at question among my companions.
The flash you see – or don’t
You either swear it exists and you’ve seen it or you don’t and you think everyone who has just may be crazy. It’s the green flash.
I suffered a little gentle derision about this little-known phenomenon last week, when a few of us were bobbing along waiting for the breeze to freshen off Santa Cruz.
About a month earlier, I’d mentioned the green flash, and that night my wife even saw it. Since we could not observe it last week, my sanity is at question among my companions.
But a quick Google search reveals a wealth of information, and even photographs about the green flash.
First, it isn’t a flash at all, but a brief period when the red or orange of the sun just as it sinks into the horizon appears to change to green or blue. To observe it, one must be above the horizon, and looking toward a level spot where the sun sets.
Last week, conditions appeared perfect. The air was clear, the ocean flat, and as the sun dropped, it first appeared as a rectangle, then a puddle of glowing crimson right on the horizon – perfect conditions for the phenomenon my friends do not believe exists.
Here’s what happens in a green flash: “astronomical refraction.” That should clear everything up.
Seriously, astronomical refraction is the angular displacement of astronomical objects from their true or geometrical position, because of the bending of rays in the Earth’s atmosphere, according to Andrew T. Young, a San Diego State University astronomer who explains it all in a Web site (http://mintaka.sdsu.edu/GF/). More simply it’s akin to a mirage and it does not occur until the sun is below the horizon. We’re seeing light rays bent through Earth’s atmosphere.
The flashes can take on different appearances, either as a light appearing above the sun, a halo around the sun’s edge or a green stripe where the last of the sun used to be as it sinks.
Your mama probably told you never to look directly at the sun. That’s sound advice. It’s not safe to look at the sun if it’s uncomfortable, or if it’s above the horizon. Be sure you’re above the line of the horizon (not staring at a line of mountains, for example), and that the sun is low enough that your thumb, held horizontally at arm’s length, can cover it. Since the brightness of the sun diminishes by a factor of two each minute when it’s nearing the horizon, a minute makes a lot of difference.
Next, Young suggests using some optical aid. He said binoculars or a long telephoto lens in the right location will increase odds of seeing the phenomenon from about 1 in 6 to as much as 5 in 6 sunsets.
Why bother? Well, watching the sun go down is an invitation to slow the pace of our lives down a little, and that can only be a good thing. It gets us outside and to a place higher than the visible horizon. That sounds good, too. Doing a little green flash hunting from Fremont Peak seems like a profitable use of a spare hour or so.
It also gives you license to bore your friends and children with a little good-natured banter about something that is real – I swear it – but so little known.
It’s also not completely understood. Young, on his Web site, asks observers who have new ideas to contribute to sound off with their ideas. The chance to ponder bigger questions, now that’s a great reason to go looking for the green flash.
