What You Need to Know Ahead of the Total Solar Eclipse

We are less than three days away from the total solar eclipse that will be seen in the US, Mexico and Canada, and there is major excitement around it. Total solar eclipses are rarely seen in the US. The next one won’t be seen for some 20 years, and they rarely last as long as this one will. Complete darkness or totality as it’s known may last four minutes. Monday’s eclipse will cut across 13 states, with more than 30 million people living in the path of totality. Millions more are traveling to get a good look. And stores are selling, or in some cases, giving away the glasses you’ll need. Our science correspondent, Miles O’Brien, has a viewer’s guide on what you need to know.

This is the one and only total solar eclipse I have ever witnessed. 2017. I was prepared to be blase, but instead I was blown away. You just have to see it to understand. Certainly this guy does. Will there be a big viewing party here?

Yes, a huge viewing party.

Neil deGrasse Tyson is an astrophysicist at the American Museum of Natural History in New York City. This eclipse, as much as anything, is about how many people can get to it, right?

The eclipse itself goes over major metropolitan areas. It kiss’s part of Austin, goes through Dallas, right on up the major cities, at Columbus, Indianapolis, Buffalo, up at Niagara Falls. People can sit in their backyards and experience a total solar eclipse without even having to travel.

What would you recommend people do? Should they get in their cars and go?

Yes. Yeah, next question.

Done.

If you were in a place, in a zone, where the moon has covered 99% of the sun, that little sliver that remains is equivalent to the light of 10,000 full moons. So if you were not in totality, you’re not in totality.

I think we intuitively know the moon is a lot smaller than the sun. So how is it-

It’s physically a lot smaller than the sun.

How is it possible for it to cover the entire diameter of the sun?

Yeah, so we have a fortunate set of circumstances as earthlings. No other planet has this feature. The sun is 400 times farther away from us than the moon is, and it’s 400 times wider. Those two factors geometrically cancel each other, if you want to think of it that way, so that they look the same size on the sky, making for spectacular eclipses.

Okay, so now we’re seeing an eclipse from the International Space Station, 250 miles, give or take, above us. And what are we seeing there?

So this is that darkened part of the moon’s shadow crossing earth’s surface. And you get to see a fuzzy edge around there. Notice it’s not a sharp boundary, because if you’re in that fuzzy edge, it means some of the sun is covered and the rest still is peeking out. So it gets darker, but it’s not totality.

You don’t want to look at the sun, unless it’s completely covered, without some protection. Tell us about that. What could happen?

Well, you never want to look at the sun without protection, and during an eclipse you have more of an urge to look at the sun. But these are specially designed to filter out or reflect away all the harmful rays that are coming from the sun. So when you put this on, you know they’re working when you can’t see anything.

I got nothing. I got nothing.

Where are you here?

Nothing, nothing.

You can’t see anything. But you look at the sun, and then there’s an image of the sun on the sky.

You should look to make sure they are the proper ISO.

Oh, yeah. So there’s an ISO certification on them, and generally they’ll say eclipse glasses. The moment the sun becomes completely covered, then you don’t need the glasses. You can remove them and look directly at the completely covered sun.

I think this is an important yet overlooked point. Remember to take them off when it’s in totality, right?

Yes.

Because otherwise you’re missing out.

Then you’re missing out. Correct.

So in 2017, Celestron, telescope maker, shot this fabulous time-lapse with the Celestron C6 telescope. Look at this thing. It came out pretty well.

Yeah.

So this is a preview. It-

And it doesn’t happen this fast, this is time-lapse.

This is much faster.

Yes. So first contact is the moment the moon in its orbit around the sun touches the edge of the sun. Second contact is when we hit the diamond ring, when this leading edge of the moon touches the opposite edge of the sun. Diamond ring, second contact.

Boom.

Okay? Now the moon, which is larger than the sun on the sky, is continuing to move. When the trailing edge touches the sun again, the second diamond ring, that’s third contact. As the moon completely emerges from this disk of the sun and it steps off, that’s fourth contact. So there are four contacts of note. And the ones you really care about are the second and third.

All right. And in between the second and third is when you can take the glasses off.

That’s total eclipse. That’s correct.

That’s totality. Your natural instinct is to look at the sun, but it’s worth looking around and seeing what’s happening all around you.

So truth leaves, we’ve all sat under trees like that before and you see these mottled circles of light. And it’s very easy to think to yourself, that’s just light coming through the trees. But it’s actual images of the sun created by pathways through the leaves. So during an eclipse, all those little circles of light turn into crescents.

But I think the point here is take a moment to look around you and absorb the environment. The temperature changes. There’s a quietness that comes along with it.

An eerie quietness.

Birds and bees do different things.

The animals of the animal kingdom are confused by this. But I think among all the animals, the ones that behave the strangest are the humans. So watch the behavior of other humans.

Where would an expert like you go to watch this eclipse?

It happens that the eclipse path goes not only over Dallas, but what is in Dallas, but the Cotton Bowl. This seats 90,000 people. So what a convenient place to gather. And this was being reserved by NOAA, the National Oceanic and Atmospheric Administration. So if there’s anyone who has power over the weather, it would be them.

And maybe they’ll make it happen for us. All right. All right, thank you very much, Neil. This has been fun. I hope you get to see it. I hope we do too.

Well, lucky for us, Miles will join us from the Cotton Bowl in Dallas on Monday where he’s going to report on the excitement around the day’s events there and throughout North America.