Things to try while watching the solar eclipse

  • #1
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We can:

0) watch the eclipse unfold with our ISO approved eclipse glasses

1) listen for insects chirping as they think night has fallen

2) make a pinhole camera from a shoe box

3) wear red and green clothing to see how our perception changes in the twilight of the eclipse (to witness the Purkinje Effect)

https://www.freep.com/story/news/lo...urkinje-effect-red-green-clothes/73154006007/

4) look for the scalloping effect as light filters through the tree making overlapping eclipse images

https://www.tennessean.com/story/news/local/2024/04/04/solar-eclipse-viewing-experience/73165540007/

Any other cool experiments?
 
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  • #2
One of the better tricks that I watched a person do during the last eclipse was to reverse a pair of binoculars (eyepieces towards the sun) and project the sun on some paper. It worked remarkably well.
 
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  • #3
perhaps @Greg Bernhardt can make this a featured thread to get more ideas.
 
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  • #7
jedishrfu said:
and NBC news:

https://www.nbcnews.com/mach/science/most-amazing-things-see-during-eclipse-ncna794496

Has a cool solar corona BW photo to open the article.
I have one major issue with this article.
article said:
During those final few seconds before totality, it's time to remove your eclipse glasses, for it is now safe for you to look directly at the sun!
I consider this an almost criminal suggestion.
I would not remove your glasses until the sun goes totally black behind your safety glasses, unless of course you want permanent eye damage.
 
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  • #8
jedishrfu said:
Make pinhole cards.
That's my go-to for eclipses. It's a lot simpler than making a whole shoebox pinhole camera, IMO, and you can put several different size pinholes on the main card to see how the size of the hole affects the images projected onto the 2nd card.
 
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  • #9
OmCheeto said:
I have one major issue with this article.

I consider this an almost criminal suggestion.
I would not remove your glasses until the sun goes totally black behind your safety glasses, unless of course you want permanent eye damage.
Good point! Alway err on the side of caution. I didn't notice that statement.

One recent radio podcast mentioned taking tge glasses off to look around but be mindful not to just glance at the sun as if you were still wearing them.
 
  • #10
Dont forget:
- the traffic so have a full tank of gas
- bring lots of snacks trail bars… because fastfood joints might become real crowded
- dont leave in a hurry like everyone else wait a few hours before hitting the road

In Texas the nearest traffic comparison i can think of was when Houston evacuated before the hurricane. It was all lanes out and very slow moving ala 10 mph or less.

Hope the eclipse road isnt that bad.
 
  • #11
OmCheeto said:
I have one major issue with this article.

I consider this an almost criminal suggestion.
I would not remove your glasses until the sun goes totally black behind your safety glasses, unless of course you want permanent eye damage.
jedishrfu said:
Good point! Alway err on the side of caution. I didn't notice that statement.
"err on the side of caution" is fine, but it's still "err". I've never seen a justification for this guidance but I can speculate on why it's fine:

The human eye has a resolution on the order of 1 arcmin, and the sun is 30 arcmin across. That means that in the last few seconds before or after totality the light is not covering one "pixel" and the intensity is greatly reduced (e.g., 30 seconds would mean something less than 1/5....I don't feel like doing geometry to see how much smaller it is). Combine that with imperfect tracking and the chance of eye damage is vastly diminished.

To repeat what I said before: if eye damage from incidental glances at the sun were a thing, everyone on earth would already be blind.
 
  • #12
russ_watters said:
To repeat what I said before: if eye damage from incidental glances at the sun were a thing, everyone on earth would already be blind
Word is that the risk is increased because the pupils are atypically dilated due to the eclipse conditions. On any normal sunny day, our pupils will be fully contracted, protecting us as they are designed to do.

Pupils can stop down as much as 18 to 24 f-stops from fully open.

I've walked home after the doctor put those drops in my eyes that open your pupils. Had to cover my eyes with my hands and anything more than a slit of light would be utterly blinding.
 
  • #13
DaveC426913 said:
Word is that the risk is increased because the pupils are atypically dilated due to the eclipse conditions. On any normal sunny day, our pupils will be fully contracted, protecting us as they are designed to do.

I've walked home after the doctor put those drops in my eyes that open your pupils. Had to cover my eyes with my hands and anything more than a slit of light would be utterly blinding.
How is this different from walking out your front door?
 
  • #14
russ_watters said:
How is this different from walking out your front door?
Generally, when you walk out the front door, you do everything you can to keep the sun out of your eyes - squint, look away, cover your eyes, look at the ground ...

We're talking about deliberately looking directly into the sun with your fovea, not
"incidental glances".

So, bad analogy?
 
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  • #15
DaveC426913 said:
... and stopping to look intently directly into the sun with your fovea?
Your description of the scenario doesn't account for the eclipse. You're glossing-over the difference in brightness. It's larger than the difference in pupil size. A lot larger.
 
  • #16
russ_watters said:
Your description of the scenario doesn't account for the eclipse. You're glossing-over the difference in brightness. It's larger than the difference in pupil size. A lot larger.
Granted. But you are likewise glossing over it in the other direction with the faulty analogy.

Unlike you, if I am wrong, people don't get permanent eye damage.
 
  • #17
DaveC426913 said:
Granted. But you are likewise glossing over it in the other direction.
??? The difference in brightness due to the eclipse is my entire point.

Note: what you're saying about pupil size contains assumptions about what it would actually be and how fast it might react to looking at the sun (eclipsed or not). But the brightness difference is still larger than even the worst case.
Unlike you, if I am wrong, people don't get permanent eye damage...
Flying is dangerous and we shouldn't do it, but at least if I'm wrong people don't die.

Anyway, this isn't my recommendation, I'm explaining why the recommendations from expert/responsible agencies makes sense. If my explanation is wrong it does not in fact mean that the guidance is wrong. There could be another reason I'm missing.
 
  • #18
The Prekinje Effect is a example showing that our eyes do not handle eclipse conditions gracefully.
 
  • #19
russ_watters said:
Flying is dangerous and we shouldn't do it ..
Correct. The uninitiated and uneducated should NOT fly planes. They will die. This is who the cautionary warnings are aimed at.

Bad analogy.

I grant that there may be an overabundance of caution in the public media. You and I know that there is only a certain amount of risk if one is intelligent about it, but on the other hand, recall that just last week a PF member thought he might suffer eye damage when he briefly saw the reflection of a laser scanner from the street as he passed by outside.

Ignorance abounds.
 
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  • #20
DaveC426913 said:
The Prekinje Effect is a example showing that our eyes do not handle eclipse conditions gracefully.
The wikipedia article on the subject does not contain the word "eclipse". Please explain.
DaveC426913 said:
Correct. The uninitiated and uneducated should NOT fly planes. They will die. This is who the cautionary warnings are aimed at.

Bad analogy.
I'm reasonably certain you know that's not what I meant and are purposely interpreting the analogy in bad faith.
 
  • #21
russ_watters said:
The wikipedia article on the subject does not contain the word "eclipse". Please explain.

I think he effect was discovered independent of Eclipses. Try Googling it along with eclipse.

https://www.cnn.com/2024/04/04/americas/purkinje-effect-total-solar-eclipse-scn/index.html

Our rods an cones arent set up for the fast change in brightness.
russ_watters said:
I'm reasonably certain you know that's not what I meant and are purposely interpreting the analogy in bad faith.
You're not suggesting being a passenger in a plane is dangerous are you?? That's just wrong.

What are you hoping to achieve with that analogy then?

Sry. Have to pick this up in the AM.
 
  • #22
One more thing, or I won't sleep.

A 99% eclipsed sun sheds as much light as 400 full Moons [citation pending], but it's concentrated in an area of just a handful of square arc minutes. That means it is likewise concentrated in a very tiny spot on your retina. Your pupil does not react as it needs to. It's not a natural scenario; its not like stepping out our front door where the entire sky is bright and your pupil can slam shut in milliseconds. People are not used to deliberately looking at such a concentrated light source against an unlit background, and their protective reflexes are short-circuited.

Don't rely on "common sense" it doesn't apply; and don't rely on analogies. We should do the math, considering all the relevant factors.
 
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  • #24
jedishrfu said:
Dont forget:
- the traffic so have a full tank of gas
- bring lots of snacks trail bars… because fastfood joints might become real crowded
- dont leave in a hurry like everyone else wait a few hours before hitting the road

In Texas the nearest traffic comparison i can think of was when Houston evacuated before the hurricane. It was all lanes out and very slow moving ala 10 mph or less.

Hope the eclipse road isnt that bad.
I left my 2017 viewing location in South Carolina about 8 hours after the eclipse. Traffic on the freeways was bumper to bumper for at least 150 miles. It wasn't until I took country roads that were well away from the freeways that I was able to make any progress at all. Unless you're viewing it from the middle of nowhere, expect lots of traffic for a long period of time.
 
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  • #25
OmCheeto said:
From a post of mine in advance of the 2017 eclipse;



Lots of good stuff in that thread.
Indeed.

"If you don’t think the danger is real, read this amazing recent interview with an optometrist on Space.com, where he states you can actually see the crescent Sun burned into the backs of patient’s eyes who stared too long at a partial solar eclipse (!) It’s a permanent souvenir you don’t want to have."
1712326927343.png

The left image shows a healthy eye. The middle is the eye of a young adult male who viewed a partial solar eclipse repeatedly without protection and suffered both thermal and photochemical solar retinopathy. Several crescent-shaped scars can be seen over and around the fovea (bright pinkish spot). He is legally blind in this eye. The far-right image shows an eye with several photochemical retinal lesions. The irregular pale "smudge" above and left of the fovea, plus the three smaller pale areas at the arrowheads, are the remnants of the photochemical injuries to that eye. The vision did recover eventually. (Image credit: Shutterstock/B.R. Chou/University of Waterloo/Used with permission)


" experienced eclipse watchers like Chou say it's safe to remove your eclipse glasses during the 2-3 seconds before and after totality to see the so-called diamond ring effect, or "Baily's beads."


This is a good article too.
https://www.space.com/37199-solar-eclipse-blindness.html
It's not just the usual fear-mongering; it explores the effects in more detail.
 
  • #26
The analogy to flying is stretched, regardless of whether riding or piloting. For flying, multiple safety measures are in place and not just in the multi-million dollar plane, such as the radar tower and runway perimeter fences that were put in places decades before your flight. For an eclipse, beyond using your brain, there is just one safety device, the viewing glasses, and that safety device is either on or off.

It is probably is safe to view Baily's Beads with the naked eye. They are caused by light from the edge of the sun passing through low spots on the lunar horizon. The tallest mountain on the moon is Mons Huygens at 5500 m, but it is not on the lunar horizon and projects above a mare, and maria are rare on the horizon. So let us assume a bead is caused by a valley of square profile 2000 m on a side. This is 0.00004% of the total lunar cross-sectional area and represents a minuscule fraction of the sun's total brightness. Taking into account that even when you think you are staring fixedly at a spot, your eye is performing microsaccades (slight involuntary eye movements), the tiny spot of light from a bead is skipping around on the retina, avoiding focusing too much energy on one area.

That said, giving such advice is dependent on the audience. For avid space.com readers, there is a good chance they traveled to the path of totality for the 2017 N. American eclipse or others, and that they've seen Baily's Beads in photos or in real life, so they know what they're looking for. The nbcnews.com readers may not necessarily have an interest in space or science, and want to participate in eclipse viewing merely because it is an event that a lot of people are talking about. It is expecting too much of them to research Baily's Bead or figure out when they occur in the timing of eclipse events, and a small percentage of them may decide they're happening before they actually are. To a general audience, I would recommend taking the safety glasses off only after all sunlight is no longer visible.
 
  • #27
DaveC426913 said:
" experienced eclipse watchers like Chou say it's safe to remove your eclipse glasses during the 2-3 seconds before and after totality to see the so-called diamond ring effect, or "Baily's beads."
That is the guidance I've been discussing, which was wrongly contradicted in Post #7. If you agree with/accept the guidance, we're good. Any broadening of the issue beyond that (such as staring at a crescent sun a half hour before totality) is not something I'm claiming.
 
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  • #28
Re: Baileys Beads and Diamond Ring, the issue the public media is warning about is that it is difficult to judge when it is safe to view with the naked eye, at least without a timer. You sort of have to take your glasses off in advance, since they only last a few seconds.

You can easily imagine how many people will pop their glasses off, not realizing there's still 30 seconds to go.
 
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  • #29
DaveC426913 said:
Re: Baileys Beads and Diamond Ring, the issue the public media is warning about is that it is difficult to judge when it is safe to view with the naked eye, at least without a timer. You sort of have to take your glasses off in advance, since they only last a few seconds.
This is the entirety of the passage in question:
As the sun's crescent narrows to just a thin line, it will suddenly break up into dots and points of light called "Baily's beads." This effect occurs as the mountains on the moon reach into the thin crescent sun and block parts of it from view while valleys permit the last remaining rays of sunlight to form glittering spots, or beads, at the edge of the moon's black disk.

This effect lasts for only a few moments.

During those final few seconds before totality, it's time to remove your eclipse glasses, for it is now safe for you to look directly at the sun!
It's saying you take off your glasses after you see the Bailey's Beads form and yes, that means only a few seconds/"moments". Nobody is suggesting taking off the glasses in advance or using a clock to judge.

My recollection is that you can't see Bailey's Beads with the naked eye anyway, you can only see it through the filter(they are too bright). You can only see the diamond ring naked-eye (being washed-out is the point of the diamond ring).
 
  • #30
russ_watters said:
This is the entirety of the passage in question:

It's saying you take off your glasses after you see the Bailey's Beads form and yes, that means only a few seconds/"moments". Nobody is suggesting taking off the glasses in advance or using a clock to judge.
Well there you go. I am an enthusiast and I get stuff wrong too. Which is why the abundance of caution directed at the uninitiated.
 
  • #31
1712347030969.png
 
  • #32
Here'a some info on getting your binoculars or monocular or range finder scope ready for eclipse viewing:

https://www.timeanddate.com/eclipse/binoculars-telescope-projector.html

Be mindful of heat build up in the scope and the possibility of setting the paper on fire.

And don't look through the scope to line it up with the sun --> use the shadow method ie minimize the shape of the shadow to roughly align the scope and watch the paper until you see an image.

Astronomy magazine published a special eclipse 2024 edition that shows a similar project using a 30" board with binocs attached to one end and a white paper screen at the other end. They too mention using a range finder scope 8x50 as an alternative to binoculars as it has fewer elements to heat up.

https://www.astronomy.com/

map info

https://www.astronomy.com/observing/astronomys-atlas-maps-totality/
 
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  • #33
Huh. I got a 6" Newt just hangin' out on the back porch, maybe I should set it up.

'cept for the fact that I gotta adjust it every minute...
 
  • #34
DaveC426913 said:
Huh. I got a 6" Newt just hangin' out on the back porch, maybe I should set it up.

'cept for the fact that I gotta adjust it every minutes...

I got a 10" salamander hangin' out on the back porch.
 
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  • #35
Hi. Maybe its the wro g thread.

I have to go to work when the eclipse happens. I live in LA. Is it safe to be outside?
 

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