Good morning, John.

This is going to be one of the most dangerous eclipses of all time. Is it going to usher in like three years of darkness and fulfill some kind of Lovecraftian prophecy? No. Things will be roughly the same the day after the eclipse as the day before it, but there are reasons why this one is particularly dangerous and I think they're very interesting.

Now the first reason why eclipses are dangerous will not be a surprise: They can hurt you in the eyeballs. But I think that this has not been traditionally explained well, like, we all know that the Sun is up there every day and most of the time we do not like go and stare at it and burn our retinas 'cause you look at it and you're like, "That is too bright. I should not look at that." Sometimes you accidentally stare straight into the Sun and you're like, "Oh my God, that was bad. I should never do that," and you don't 'cause even babies stop doing things when they hurt.

The reason eclipses are dangerous is because they confuse us. All of our previous experience with the Sun has indicated that if we look at it and it hurts us, we should stop. But if you are in a situation in a place where it's like 95% or 90% of the Sun is covered up by the Moon, like it's almost to totality or you're in a place where it gets close to totality, your brain might look at the Sun and think, "That's not that bright. I can look at that." And your brain is wrong. It is not really the amount of light that comes from the Sun that's dangerous, it's the quality of that light. It is extraordinarily high-energy light, so even if it's just a tiniest sliver of Sun still visible as the Moon goes over it, if you look at that for as little as a few seconds you might permanently damage your eyes. Now most the time, the retina will heal. But sometimes it will not. And that goes for whether you're looking through sunglasses or window tint or even a welding mask. The Sun's light is more damaging than a welding arc, like we do not get how powerful the Sun is. It powers the whole planet. It's very strong.

Now the second reason that this eclipse is so dangerous is even worse, because you are not going to die of a burned retina. But, over 200 million people live within driving distance of this eclipse, and just like the Sun is brighter than you think it is, driving is more dangerous than you think it is. We actually saw this in the numbers leading up to the 2017 Eclipse. Fatalities and car crashes went from the background rate of around 7.9 deaths per hour to over 10 deaths per hour. And yes, in the United States of America, car fatalities can be measured in deaths per hour. That is a scary fact.

Now, traffic fatalities did not go up because like the Sun blinked out and people crashed their cars. It just went up because there were more people on the roads going to and from places where they could see the eclipse.

There are two parts of any danger. There is the risk and there's the number of people exposed to the risk. Like going to Mars is very dangerous but it's not a big public health concern 'cause not a lot of people do it, and the reason why this eclipse is more dangerous both in terms of potential retina damage and in terms of car accidents, is because it is available to so many people. This is a wildly populous eclipse. Most total eclipses go over only the ocean. This one goes over only land. That's not true, it also goes over some ocean. Of course it goes over some ocean, like the we are an ocean world. But it will cover more than 50% of Indiana and then the Northeast, it's very close to a lot of very large population centers and people are traveling for it. I'm traveling for it. I'm really excited to see this eclipse. This will be my first total solar eclipse. Will it be cloudy? Probably, but it's still going to be cool, okay.

But just like there are ways to protect your retinas while you are eclipse hunting, there are ways to protect your body while you are driving, and the main one is to not be distracted. You might be a very good driver but the people around you aren't and you have to keep an eye on them, and anytime you are not paying attention to what's going on around, you increase the chances that something very bad is going to happen to you or to someone around you—whether they are in your car or outside of your car. And yeah, you thought you were coming for a science video and you came for a Public Health Announcement to not look at your freaking cell phone while you're driving. I feel it too. The tug from my pocket, it's like, "Oh I could do it. I could do it. I could do it. I can see there's a thing that I need to look at right no-" Don't! Don't! I see you doing it.

If you want to see more eclipse specific content, I got a video up on hankschannel where I answer some SciShow questions about the eclipse. And there's also a ton of eclipse related content in this week's newsletter which you can get at the link in the description.

John, I'll see you on Tuesday.