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I know this sounds like a really stupid question. But since I have never seen one or even used solar eclipse glasses I assume when I can no longer see the sun through the glasses then it is safe to remove them in order to see the sun's corona. OR when it appears to be night perhaps?

Maybe I am too cautious.

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    $\begingroup$ Based on my experience with the 2017 eclipse, the best sign that it's safe to remove your eclipse glasses is when the crowd around you starts cheering wildly. $\endgroup$
    – Mark
    Feb 16 at 2:27
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    $\begingroup$ Mr. Eclipse (Fred Espenak) says it's safe to remove them about 1 min before totality. $\endgroup$ Feb 16 at 16:54
  • $\begingroup$ @GregMiller That might damage the eyes. It's probably better to wait until five or ten seconds or so before totality to look at the Sun with the naked eye. Seeing the very moment of totality is very special, so looking at the Sun right before totality is a good idea (and is not eye-damaging). A good eclipse calculator and a good clock are essential. Note that with the eclipse glasses on nothing is visible through those glasses during that last minute, so Fred Espenak is correct in this sense. Take them off, look at your watch. Maybe set an alarm for ten seconds prior to totality. $\endgroup$ Apr 9 at 13:22
  • $\begingroup$ Keep your glasses on until totality. While it will not do any permanent damage in the last few seconds, the bright sliver of the Sun will leave temporary afterimages in your eyes and you will miss valuable seconds of total eclipse. $\endgroup$ Apr 11 at 12:47

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Eclipse glasses are so dark that nothing can be seen through them, except the surface of the sun.

When you are looking through the eclipse glasses, if you can see any part of the sun at all, it is still too bright to remove them. As soon as the sun is no longer visible it is safe to remove them and view the solar corona.

As soon as the sun returns, you should replace your glasses if you want to view the growing crescent of the sun. Basically, any time the surface of the sun is visible, you need to use glasses to look at it. But when the entire surface of the sun is covered by the moon then it is safe to look without glasses.

Consequentially, during a partial or annular eclipse, it is never safe to look at the sun without proper eye protection.

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    $\begingroup$ Since the question was explicitly about a total solar eclipse this might already be clear, but just in case, this also means that for an annular or partial solar eclipse it's never safe to look with bare eyes. $\endgroup$
    – Emil
    Feb 16 at 12:43
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    $\begingroup$ I'm no astronomy or spectronomy expert, so I'm not going to write an answer, but... @James: I recall having been told that you should keep the glasses on at all times when looking in the direction of the sun. This is because even when you might not be able to see the sunlight anymore, there's still plenty of energy in wavelengths that our eyes can't observe. Despite us not being able to see them, they can still cause damage to our eyes. Do you think this was nonsense they told me? Or does it somewhat make sense? $\endgroup$
    – Opifex
    Feb 16 at 13:25
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    $\begingroup$ @Opifex Whatever UV the corona may produce is tiny compared to simply looking at mundane objects on a sunny day. You don't need eye protection during totality. The problem is that when it's not quite total and the sun is a sliver, the light isn't bright enough to cause pain (which is your eye's defense mechanism), but there's enough UV light that when your eyeball focuses it, it can cause a sunburn on your retina -- the same condition as snowblindness or welder's eye. The answer is correct: glasses off when you can't see anything through them, glasses on as soon as the sun starts to peek out. $\endgroup$ Feb 16 at 20:07
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    $\begingroup$ I mean, during a partial you don't take off the glasses at all, so "When can I take off my glasses" is a moot point there. I'd hate for people to get confused and miss out on the upcoming total eclipse because they hear "during the eclipse, do this" and don't recognize that "during the eclipse" doesn't mean the same as "during totality". $\endgroup$ Feb 16 at 21:52
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    $\begingroup$ If someone doesn't remove their eclipse glasses during a total eclipse, they'll see absolutely nothing during totality (speaking from personal experience). That would be a spectacular (no pun intended) shame. Yes, there are brief moments directly before and after totality where one still should be using the glasses but it's hard to time them exactly. $\endgroup$ Feb 17 at 1:22

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