Eclipse Safety

I have a little baby daughter (as I'm writing this), and even she knows that it hurts her eyes to look right at the sun. So, she doesn't do it. What does she know that we don't?


Well, nothing. I mean, she knows it's bright and makes her squint, but she doesn't know anything about Ultraviolet Light, that tanner of buns and cooker of retinas around which an entire industry has been created (which tries to teach us that sexiness now is a fair trade-off for skin cancer later).

Ultraviolet light will cook a blind spot into your retinas pretty quick, without your even feeling it, and that blind spot will be permanent! If you are looking right at the sun (which is a wonderful source of UV), then the blind spot will be right in your center of focus, and you will never be able to see anything clearly again.

Is that enough reason not to look at the sun?

You can use a filter to look directly at the sun, but you must use specially-designed solar filter material. You are gambling your eyesight for the rest of time on the filter you use!

Do not use sunglasses. Do not use exposed film. Do not use smoked glass. Do not use a CD, or aluminum foil, or a Pop-Tart wrapper. Do not use anything just because it looks like it might be dark enough. Only use filters made for the express purpose of protecting youu eyes while you are looking directly at the sun! The little cardboard glasses you see advertised and handed out by astronomical companies and governments prior to eclipse day are fine, because they are made of the right material. There are companies that sell these on the Internet - Rainbow Symphony is probably the most well-known, and they have great information on their site about eye safety.

Do not look at the sun using any optical device, camera, mirror, telescope, lens, videocamera, or anything including your bare eyeballs unless they are fully protected by these filters. If you do not know how to use the filters, or how to read the instructions that come with them, then you should not be setting the setup up. Ask someone who knows what they are doing. Read Astronomy or Sky and Telescope magazine to find suppliers for this filter material, and follow the directions!

Note: You can look at the sun on TV, because you're not looking at the sun! The people who set up the TV feed are OK because they've taken the precaution of using the right filters.

This seems clear enough. Still, I have had enough questions from otherwise very intelligent people to tell me clearly that there is some question about this whole mess, though. So, here goes with the most important rule of all:

DO NOT LOOK DIRECTLY AT THE SUN AT ANY TIME WITHOUT SUITABLE FILTERS, EVEN FOR A MOMENT, WHEN ANY PART OF THE SUN'S DISK IS VISIBLE!

Is that clear enough? No? You want to know about when it's total? annular? partial? Should you use a filter when it's total? What about the "transition" times? OK, let me say it again, with some explanation to follow.

DO NOT LOOK DIRECTLY AT THE SUN AT ANY TIME WITHOUT SUITABLE FILTERS, EVEN FOR A MOMENT, WHEN ANY PART OF THE SUN'S DISK IS VISIBLE!


Here's a little chart to help you out:

What's going on

Suns's disk visible?

Safe to look at
without a filter?

No Eclipse

Yes. Duh.

NO!

Partial Eclipse

Yes, even if it's a sliver.

NO!

Partial Phases of Annular
or Total Eclipse

Yes (see above).

NO!

Annular Phase of
Annular Eclipse

Yes, but it looks
like a ring now.

NO!

Total Phase of Total Eclipse
(* SEE BELOW *)

NO!! The moon is
covering it!

YES!!

Lunar Eclipse

You're looking at
the moon!

Oh, yeah. Right.


Now, that should be clear enough. There is, however, a little bit of a gray area, about which I can try to give even more of an explanation. I've had some people ask me about when it BECOMES safe to take off the filters from your eyes during a total eclipse, during the transition from the end of the partial phase (when you NEED a filter) to the beginning of the total phase (when you don't). Well, if you've never seen an eclipse, you haven't yet seen the dynamics of what's going on. There is usually a few-seconds-long interval during this transition when Bailey's Beads or the Diamond Ring is visible, and these few seconds are longer than you think. Yes, it all happens VERY fast, and it leaves you breathless and screaming like a fool and all that, but as far as your eyes are concerned, those few seconds are a long time to be staring at that little piece of the sun's disk (which is all that the Beads or the Ring really are). SO, technically, you cannot safely look without filters until the Diamond Ring is gone. And, on the back end, you need them the moment the Diamond Ring comes back again. (You can tell when that's going to happen, believe me!)

There is almost always someone among the group you are watching with who will have a whistle, and they will blow it at these times. Those are your signals, if you can't take enough responsibility for your eyes to try and figure it out yourself.

Now, does everybody do it exactly that way? No. Everyone sneaks a peek too early at second contact, and hangs over a little at third contact, for their eyes to be truly happy and safe. Does that mean I recommend it? No. Do I do it? Yes. Do I probably have little blind spots all over my retinas from it? Maybe. I don't notice it, but maybe what I call old-age degeneration of my eyesight is really the result of a few too many seconds my retinas have spent "juuuust a bit outside" the shadow! You do what you want, but please don't try suing someone for your own actions if you do something stupid. That really honks me.

Here is an example of what not to use. These glasses are nowhere near dark enough to be safe,
yet in 1932 they were marketed and touted as a "scientific" product for just that purpose. Shudder.

I'm developing some ideas about how to ensure eye safety among kids when they're given the educational opportunity of experiencing eclipses. By 2017, I should have it all figured out!

© 2000-2007 Dan McGlaun