Brent's Two Cents

You'll Go Blind!

You have to love the web.

Anyone who knows me more than very casually knows that I'm something of a skeptic, and that ever since reading the Demon-Haunted World I've been devouring skeptical literature. Over the past few years I've developed a love for the non-intuitive: which I define as any true claim that makes you sit up and say "No way!" Very often, these claims are old wives-tales, or things that make some sort of sense so we accept them uncritically. Until today, my most recent favourite was the fact that reading in dim light doesn't cause eyestrain. At present, I have pretty good vision, and for whatever reason seem to prefer reading in a little bit dimmer light than most people. I can't count how many times I've been told I'll go blind from reading in not enough light. Whenever I'm reading over at Stella's parents' place, one or the other of them is guaranteed to turn up the brightness of the light I am using. (To be fair, your eyesight does get worse as you get older, so the light may very well be insufficient for them, but I can see just fine.)

Which brings me to why I love the web. This morning, a trivial discussion with Stella on the reason that the sky is blue* led me to a discussion of the Green Flash, an interesting set of phenomenon that can sometimes be observed at sunrise and sunset. While reading the pages describing how to see and photograph the Green Flash, I felt slightly uncomfortable. It seemed weird that on this page there was no huge warning disclaimer of the sort that we are so accustomed to seeing in our society, admonishing the reader to not look directly at the sun.

Well, it was there, but not at all what I expected. On a page that began with a discussion of Galileo's blindness (which was not caused by looking at the Sun), the author makes the startling claim that casually looking at the Sun won't make you blind. He doesn't just make the claim, he discusses various types of eye damage in detail and summarizes with:

Is it possible to injure your eyes by looking at the Sun? The answer is "Yes, but you have to work at it under normal circumstances."
Can you become totally blind from looking at the sun with the naked eye? The answer according to Mulder, and from the cases of solar retinitis in the literature, is "No".

There's even a story about a researcher who asked some folks who were going to have an eye removed for medical reasons to stare at the sun with their doomed eye for a few minutes and report the effect on their vision, which were not extreme.

This resolves a mystery that has plagued me for decades: "Why am I not blind?" I vividly recall sitting on a swing at the park near my house one day when I was in elementary school and staring directly at the late afternoon sun for at least a couple of minutes. It never really felt uncomfortable and I suffered no permanent damange — I just saw spots for a while afterward. At the time I thought that maybe I was Superman or something, but I guess I'm just normal.

* And by the way, the sky isn't blue. In Vancouver it's usually grey. At night it's black. At sunrise/sunset it can be orange or pink. The question should be amended to "Why is the blue sky blue?"

Posted by Brent Marykuca at September 12, 2003 11:07 AM