Like ‘some invisible force is taking a bite out of the sun’: What to expect on eclipse day in Texas

April 8 is shaping up to be historic day across a large swath of Texas, as a total solar eclipse blocks the sun from view for a few breathtaking minutes.

But what will the hours and minutes leading up to the eclipse be like? How should you prepare if you will be in Eagle Pass, Fredericksburg, McKinney or another location in totality’s path? And what will you be able to observe about the sun and the moon?

Angela Speck, who chairs the physics and astronomy department at UT San Antonio – and is a veteran of many an eclipse – offers lots of tips and tricks for having the best experience on eclipse day. Check out her advice below, and listen to an extended interview with Dr. Speck in the audio player at the top of this story.

Eclipse day timing

On eclipse day, the moon will fully obscure our view of the sun in early afternoon – I believe it’s about 1:30 Central time or so.

The solar eclipse begins with what we call first contact. That’s when the moon first starts to impinge on the disk of the sun. And that happens at about 12:15, maybe closer to 12 if you’re Eagle Pass and closer to 12:30 or so in northern Texas. But it’s basically 12:15ish we start to see a partial eclipse.

If you don’t pay attention, if you don’t have special viewing devices, if you’re not looking at shadows, you wouldn’t even notice for another hour that anything weird was going on, because your eyes adjust as the sky gets dark; your pupils get bigger, and you can see the light just looks the same.

So when we talk about the sky getting dark, even about a minute out from totality, the sky is only like an overcast day – hopefully it’s not overcast; hopefully it’s clear – but the darkness is like an overcast day. It’s not super dark, but in the course of the next minute, it drops from overcast day to nearly full moon dark in one minute. It is faster than sunset even in the places where it sets really fast.

What you see before totality

Even when you get to like 99%, even when you’re really close to fully eclipsed, it’s still not that dark. Many people will have witnessed the Ring of Fire eclipse, a very good partial eclipse in October of last year. And it just didn’t get that dark.

And so you really don’t notice it getting darker until the sun is 75% eclipsed. And even then, it’s subtle, and it’s kind of like on a cloudy day when the sky sometimes goes green before hail, and you’re like, “whoa, the sky looks weird.” It’s like the sky is the wrong color.

During this solar eclipse, we do not even see the moon at all. Basically, what happens is, as the moon moves in the way, it just looks like some invisible force is taking a bite out of the sun. We do not see it because it’s not lit up. The side that is pointing towards us has no light on it, and so we don’t see it at all. Once it’s completely in the way, we see what looks like a black hole, because it’s the unlit side that is pointing towards us.

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Shadows from a partial eclipse are seen on a garage door on Oct. 14, 2023. Deborah Cannon / KUT News

Look into the shadows to see more

So the most fun thing to do is to look under trees. As you’re looking under a tree, what happens is that all of the gaps between the leaves act as pinholes. So each of the holes, each of the gaps between trees generates an image of the sun. It does that every day. On a normal day when it’s sunny, if you look under a tree, what you’re seeing is lots and lots of overlapping images of the sun system. On a normal day, the sun is just a circle.

Anything with holes will work [for viewing shadows, like] taking a colander. In October, some of my faculty were using Day of the Dead masks that had little holes that looked like doilies. It doesn’t matter what shape the holes are, each one will make you an image of what the sun looks like in that moment.

So as you’re looking around, say, a park bench that has holes in it will make images. If you have a straw hat, that will make images. So there’s a lot of things to look at in the shadows.

The colander actually works pretty quickly, or if it’s just a nice isolated hole, so that you can see it even when there’s only a small part of the sun eclipsed. Whereas on the trees, because you’ve got lots and lots of holes and they’re kind of randomly spread out, you don’t really see it until it’s about 50 to 75% eclipsed, just because there’s too many things overlapping on top of each other.

It’s kind of fun to just play around with the shadows. You can make waffle patterns with your hands. I’m actually going to be carrying a disco ball. The same thing that happens with the gaps between the trees or the colander with the with a hole happens with the little squares of mirrors: It makes images of the sun.

In a disco, you’ve got lots of square mirrors. But the lights that are reflected on the sides of the disco hall are circular, because your light bulbs are circular. And so it’s doing the same thing. So even on a normal day, you can get it to give you nice circular images of the sun. But on eclipse day, it will give you that crescent look where the moon is biting out of the sun, and you can see the crescent shape.

I had a lot of fun with this in October. It’s absolutely fine because you’re just looking at it reflect. You’re not looking at the mirror. You’re looking at the spot on the wall.

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Jack Cooper fits his dog, Henry, with glasses as a partial eclipse takes place on Oct. 14, 2023. Deborah Cannon / KUT News

Animal behavior during an eclipse

There’s really interesting animal behavior. Some people witnessed it during the Ring of Fire eclipse back in October. But basically, at the same time that we start to notice that the skies are a funny color, so do the birds. But instead of going quiet, they do what they do after sunset. They do this kind of swarming thing where they flock and they make lots of noise. And so they’re just flying around doing their bedtime routine.

Also, if you happen to have cows handy, they will go back to the barn or wherever they sleep, because, “oh, yeah, the sky is the right color. It’s time for me to go to my where I go to sleep.”

So there’s actually quite a lot of studies being done during this eclipse on different animals at different zoos and other locations around the country, and not just in the path of totality.

If deer would normally be running around after the sunset but before it gets dark, they will be thinking “it is time for me to do my running around thing.” And so yes, those are exactly the sort of things that we need to pay attention to.

Studies are being done on other insects, but in 2017, it was shown that bees stop buzzing during totality.

Eclipse viewing safety

You should wear eclipse safety glasses anytime you look at the sun, except during totality. So you can actually use them on a normal day. Right now, the sun is very active and so it has spots. And so if you’ve got reasonable eyesight, even without any magnification, no telescope, no nothing, you put on those glasses and you can sometimes see spots on the sun.

But if you don’t have them, do not stare at the sun ever, unless is totally eclipsed.

Weather changes

It depends on the temperature and the humidity, but it can drop by 10 degrees Fahrenheit. So you really feel it. And that change in temperature means there’s a change in pressure in the air. And that means you get breezes as well. And so you get breezes on your skin.

And then you got sounds again. So we talked about the birds doing their bedtime routine, but once it plunges into darkness, you have an absence of noise. The birds have all landed and gone quiet. Now the chances are you won’t notice that because all the people around you will be screaming. They always do.

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What you’ll see close to totality

There are several more things to look out for. So first of all, you’re looking up at where the sun is at this point. You do not have the glasses on. If you have the glasses on, you won’t see anything. What is left of the sun is its corona – its atmosphere. It’s only as bright as the full moon, so it’s only as dangerous as looking at the full moon.

At the same time, you can see little bits of pink really close to the sun. The moon just looks like a black hole right next to the moon. And at the edge of the corona, you see these little pink bits – those are the prominences, the loops of gas that are sticking up off the surface of the sun. It’s amazing.

And that pink stuff, it really is pink. People think of the sun as being yellow, but that gas at the surface, it’s low density, and it’s pink. And so it’s really cool to see.

At the same time, it may get dark enough to see stars, but it will certainly get dark enough to see the brightest planets, which will be Venus and Jupiter. And if it gets dark enough, you’ll also see Saturn and Mars, maybe Mercury. And there’s a comet. So depending on how dark it gets, you might be able to see a comet close to where Jupiter is in the sky.

If you’re looking up towards the sun, there’ll be one planet on either side. And they won’t be that far away. It’ll be a few degrees that you turn your head through to see it.

It’s only as bright as a full moon. It’s completely safe to look at. The only concern is as the moon continues to move; it’s moving out of the way eventually. What happens is the moon moves out of the way, and the first place that light can get through will be a deep valley on that side of the moon.

So there will be one spot where the sunlight comes in initially. And so what you see is called the diamond ring effect, where this light comes through, and it’s so bright that it really pings. And you only need to look at it for one second, and then you know that the sun’s coming back. You look away, and you put your safety glasses back on.

There are two more things that people should pay attention to. One is what’s called Baily’s beads: As the moon is moving in the way, the last thing you see is actually what looks like beads of sunlight on the surface of the moon, where it’s essentially valleys that are letting in sunlight and mountains that are blocking them out. And so you see what looks like beads. That’s something that’s right before totality.

Then during totality, there are sunset colors all the way around the horizon. So it’s full moon dark up by the sun, but as you move your eyes down to the horizon, it’s getting lighter and lighter. And on the horizon it is the sunset orange and yellow colors. And you see those all the way around, all 360 degrees.

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How long will totality last, and where?

If you are on the edge of the path of totality, you get a few seconds. As you move towards the center of the path, then you get more time. So up in the Hill Country, in places like Fredericksburg and Kerrville, they’re getting nearly 4.5 minutes. But even not that far from the edge, so UTSA is maybe 10 miles from from the edge, and we get nearly 2.5 minutes.

So I think the really important thing, more for San Antonio than Austin, but for both of those cities, is that both of them are on the edge of the path. And so actually for San Antonio, downtown does not see totality. It gets a 99.9% eclipse, and that’s not enough.

Keep the glasses on. But you will not experience the corona or any of that stuff if you are in a 99.9%. It’s one of the cases where people are like, “oh 99.9 sounds great.” Well, you still have a thousand times more light coming from the sun than comes from the full moon. It just doesn’t get that dark. So people who are going to the Alamo or the Riverwalk, it’s like, no, go there after the eclipse. Go further north or west and enjoy the full show.

In Houston they also didn’t get the Ring of Fire. And they will get a partial; it will be a deeper partial than they had in October, but it will still just be a partial. So they will get a nice skinny crescent sun, but they will not experience all of the things we’ve described that happen during totality.

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