They say that it’s damaging to the eyes. Are there documented cases of people losing all or a portion of their vision from doing this? Also, can someone wear UV-protection sunglasses to look directly at the eclipse, without harm?
Looking at an eclipse without eye protection is no worse than looking at the sun without eye protection. UV-protection sunglasses are not strong enough to allow direct viewing of the sun, in fact, welder’s goggles are not strong enough.
But a quick glance at the eclipse is no worse than a quick glance at the sun.
Sure they are, as long as they’ve got a shade rating of 14 or higher.
Viewing a total eclipse, during totality, is absolutely harmless. The corona is only about as bright as a full moon.
It’s all the stuff before and after that’s the problem. (Totality only lasts a few minutes.)
Most people glance at the Sun plenty of times during their lifetime. As long as it’s a glance, the damage is minor, and most people will never have a problem. But an eclipse is just so fascinting that people don’t glance - they stare. That’s the problem, and the reason the authorities beat the Don’t Look At The Sun! drum when an eclipse is coming to town. Or recently, during the Venus transition. (Incidentally, I doubt you would have had a chance of seeing Venus with the naked eye - it was very very small against the massive Sun, I expect it would have simply been lost in the glare.)
There are plenty of safe ways to view the Sun, whether during an eclipse or not. Most are fairly cheap, some are even free. Your vision is precious and irreplaceable. I’d call it a no-brainer, myself.
For a fully documented article on the dangers of eclipse viewing, NASA has a great page.
I’ve seen three total eclipses. As flodnak says, naked-eye viewing of totality is perfectly safe - it’s dark enough that you wouldn’t see anything through protection strong enough to shield your eyes from full sunlight.
For viewing the partial phases, I use special eclipse glasses, which are made of aluminised Mylar film. Through them, the sun just looks like a pale disk, with no glare whatsoever.
There’s nothing about an eclipse that makes it intrinsically more dangerous than looking at the sun normally - a bad idea, although I used to stare at the sun quite often as a child ( :wally )
And just because I finally got round to making the montage, here’s a pic made up of muiltiple exposures. I shot the partial phases through a sheet of the Mylar film - that’s roughly what you see through the glasses.
The total phase is shot “as is”.
A total eclipse was visible in 1999 in a band across western and eastern Europe, and of course the partial eclipse was available throughout the region. In England, at least, for weeks before the eclipse, the media gave massive publicity to the dangers of looking at the sun without protection, and inexpensive eclipse viewers were about as available as chewing gum–you could get them in convenience stores, newstands, bookstores, drugstores etc. When eclipse day arrived much of the country was actually clouded over. Yet some people did manage to damage their eyes, though not as many as was feared:
The real danger from looking at the sun is the infrared rays. They will burn cells quickly, and you won’t know it because the retina has no pain receptors. Some people have been hurt because they used materials that were dark to visible light, like multiple sunglass lenses, without reducing infrared.
As others have pointed out, looking at a *total * eclipse is safe. You are basically standing in the shadow cast by the moon. But except for the very short period of totality (typically one to three minutes) looking at the sun during an eclipse is like looking at the sun at any other time: dangerous to your vision.
The NASA link above is excellent. Here’s a couple more:
Of course, you can go a bit far in the other direction. My junior high school shared a building with an elementary school. On a day an eclipse was taking place, I looked outside to see a teacher from grade 3 or something leading a group of children across the yard to a portable classroom. It took me a minute to realize the reason they were all holding their books over their heads like it would protect them from death rays was that someone went a bit overboard on the “Don’t look at the sun!” speil. (I’m protected --> )
Thanks, Colophon - That a gorgeous shot. Very nicely captured AND presented. You’re lucky - that’s one TOTAL eclipse!
We looked at even a partial eclipse through overexposed x-ray film, after a guy told us his opthamologist had recommened that method, and gave us a sheet of it. We cut it up and looked through two layers. It was much dimmer, and no one has had any problems. This was in 1991.
As reported in the latest Sky and Telescope (Sept. 2004, p. 92)
“I was amazed when the red disk of the Sun finally loomed through the thick ocean fog - Venus was obvious at a glance, presumably magnified by the same illusion that makes the Moon seem gigantic when it’s on the horizon.”
This was a naked eye observation made from the east coast of the US.
Yep - if you were lucky enough to have thick fog that dimmed the sun down so there was no glare, I’m sure Venus would have stood out pretty well.
A couple of years ago, in similar circumstances (the sun was about to set over the sea, with a bank of fog on the horizon) I saw a large sunspot with the naked eye. I posted about it here (under my old name).
Of course, some people told me I was at risk of damaging my eyes by looking at the sun, but I don’t see how, as it was just a faint red disk.
Odd… the SDMB is obviously cleverer than I thought, and even though that thread came up in the search as posted by r_k, it’s been renamed.
This is wrong, wrong, wrong. The reason is that a partially (or worse, an almost fully) eclipsed sun is much dimmer in total light output that your iris will not contract enough to save your retina from damage due to the unchanged intensity of the remaining sliver of sun. You are somewhat protected when looking at the full sun due to the large amount of light.
Related question: What about sunsets? Does the extra atmosphere between you and the sun protect your eyes? I’ve looked at a lot of sunsets as I’d imagine a lot of other people have - the intensity is clearly not as bad - is it dangerous to look at them?
With respect, I’m not sure flex has it exactly right either. The iris never contracts the pupil enough to protect the eye from looking directly at the sun–it would have to close completely–but ordinarily, we don’t look at the sun because the intensity essentially forces us to turn away. Besides, it’s too bright to see anything interesting anyway. During an eclipse, as the sliver of the sun gets smaller behind the moon, it looks dimmer. It’s easier and more tempting to try to look at because there is less visible light. But the infrared and UV during an eclipse, even up to the last couple of seconds before totality, are plenty strong enough to burn your eyes, even if the pupils are contracted as much as possible. In a sense an eclipse is an “attractive nuisance”–it encourages us to do something that we wouldn’t ordinarily think of.
I think the thing about looking at a sunset is that as the sun gets closer to the horizon, the radiation is passing through more of the atmosphere where it is deflected by moisture, dust etc. That’s why the sun seems to change color; some wavelengths are reduced more than others. But I’m not sure that you can rely on sunlight being reduced enough to ever make looking at a sunset safe for more than a second or two at a time, especially since you can’t see infrared. Standard solar filters reduce the sun’s energy by a factor of more than 100,000. I woudn’t be willing to bet that clouds and dust could be as effective.
For another perspective, this astronomer has reviewed the medical literature going back to Galileo and concluded that looking at the sun isn’t nearly as dangerous as most of us think it is:
He also contends that infrared isn’t the primary problem. Personally, I’d rather not experiment with my vision.
Great cite, observer11, which tends to confirm what I was saying that the primary protection from the sun is the iris contracting to reduce the incoming light. Solar eclipses reduce the incoming light enough that the iris will not contract enough causing damage to the area of the retina exposed to the remaining sliver of sun (where the intensity is unchanged from a normal sun).
On a related note, I once looked at the normal noonday sun (in Texas - high latitude) through binoculars for several seconds when I was a child and didn’t know any better. That image is thoroughly burned into my memory, but not my vision, thankfully.