The Current - Scientists are creating solar eclipses on demand

Episode Date: December 16, 2024

European scientists have launched the Proba-3 space mission, which will study the sun by creating artificial solar eclipses. An astronomy reporter explains how it's possible and what mysteries about the sun scientists hope to solve through this research.

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On Drugs is available now wherever you get your podcasts. This is a CBC Podcast. Hello, I'm Matt Galloway, and this is The Current Podcast. A solar eclipse is a stunning and rare phenomenon. Total solar eclipse, even more rare. If you've seen one, and we were lucky enough to see them in many places across this country not so long ago, there's a real feeling of awe and wonder that you kind of experience

as the sun begins to disappear. For scientists, an eclipse is a great opportunity to learn more about the sun. Now those scientists will be able to see those eclipses on demand. The European Space Agency has launched a mission called PROBA-3 to create artificial solar eclipses. Lisa Grossman is an astronomy reporter for Science News. Lisa, hello. Hello, thanks for having me.

Why do scientists want to create an artificial solar eclipse? Well, a total solar eclipse is one of the only times that you can observe a certain part of the sun called the lower, the inner corona. The corona is the sun's diffuse outer atmosphere. And if you've seen pictures of a solar eclipse where there's those big wispy or peaky kind of arms waving off of the sun,

it's kind of like a cartoon of the sun where you draw the little spikes around it. But you can only see that when the bright disk of the sun is blocked. And from the Earth, you can only see that during a total solar eclipse when the moon moves in front of the sun. So what these satellites are doing, what this spacecraft mission that ESA just launched is doing, is having two satellites in space that will create eclipses for each other. Explain how this is going to work. I've heard it referred to as eclipse on demand. Yeah. So one spacecraft will be the one that has like the camera that's taking observations of the sun, and then the other one will move in front of it, and they're going to fly in really precision

formation. So, and this is new, too. This is kind of a technology demonstration part of the mission where they're going to show how they can fly and really, really lined up perfectly with each other so that the second spacecraft blocks the sun, but only the bright disk of the sun, not more of it. And this is different from how other spacecraft that have looked at the sun do it, because other spacecraft have used kind of internal disks that block more of the sun than just the bright disk, because there are some funny optics effects that happen at the edge of the disk if it's too close to your camera. And the moon is a really perfect disk for this because it's so far away and casts a very sharp shadow. And so these two spacecraft are going to be far enough away from each other that they can cast a sharp shadow too, and it'll bring this rarely seen part of the sun into view whenever scientists want, basically.

This sounds like something out of a James Bond movie. It kind of does. How long will those eclipses on demand last? Each one will last six hours. And a total eclipse from Earth lasts only a couple of minutes. The one that we just had in April was, I think, four and a half minutes at the longest point. And that's pretty good. And eclipses on Earth only happen once or twice a year.

And you have to make sure that you're in exactly the right spot and that you don't have any bad weather. It's very rare and unusual and special to see a total eclipse from Earth, but you only get a little snapshot of it. So with six-hour eclipses every day, the mission's going to last for two years. So they're going to get a thousand eclipses or more for six hours each. So we'll be able to see how this part of the sun changes over time. We down here on earth will not see six hour solar eclipses, right? Unfortunately, no. No, it kind of sounds like that, doesn't it? Eclipse on demand, that you can just like move the moon right into place, but that's not how it works. What could possibly go wrong with that, right? What could possibly go wrong with that, right?

What is it that the scientists will learn from this part of the sun's corona by being able to do this on demand? Yeah, there are a couple of things that, a couple of big mysteries about the sun that scientists think can really have their answers in this part of the corona. One of them is that the corona is like a million degrees hotter than the surface of the sun, which is weird because usually when you move further away from a heat source, it gets colder. But on the sun, there's like, you know, the bright, big burning star part. And then as you move further away from it, it gets hotter. And so what is going on there? And we have some ideas, but we think that all the good stuff is actually cooking in this part of the corona that we can almost never see so hopefully we'll get some insight into that another thing is that the this part of the corona where the you know the

surface of the sun kind of transitions into the environment of the solar system. The sun can send out big bursts of energy. You may have seen or heard of these solar flares or coronal mass ejections, and those can affect Earth. Those can affect satellites and other electronics on Earth. They also are what's responsible for auroras, for the solar storms and the northern lights

that we saw some beautiful ones earlier this year too. So it would be really nice to be able to predict when those are coming with more precision than we have now. And scientists think that the inner corona is where those are launched also. That's one practical way that this will help us here on Earth. And it doesn't put us at the center of the universe, but are there other things that we might learn from this kind of science that would help us here on Earth? And it doesn't put us at the center of the universe, but are there other things that we might learn from this kind of science

that would help us specifically practically here? That would help us specifically practically here? Yeah. Being able to predict these solar storms and then be able to prepare for them in advance, I think, is the most useful thing here on Earth. And other than that, the thing that excites me is just the, you know,

mysteries of the universe, just knowing how it works. Do we know when the first eclipse is going to be, the first artificial eclipse? Yeah, the spacecraft launched on December 5th, and they're getting ready and doing their commissioning stuff now, and the first one should be in early 2025. It's kind of amazing that, I mean, you've hinted at this, but the precision such that they are able to, these spacecraft be in formation to be able to block this in precisely the right way is kind of remarkable. Yeah, it's really cool.

It has not really been done before in this way. And to hold that formation for six hours at a time is really going to be amazing too. And then if it works, then this could be used for future spacecraft also that could fly in formation and do other interesting things in space. You mentioned what happened in April, where so many of us were able to see a total solar eclipse. And we were standing out on the street in front of the house, and it was cloudy, and all the neighbors are there, and we had the glasses on, and we're staring to see a total solar eclipse. And we were standing out on the street in front of the house, and it was cloudy, and all the neighbors are there, and we had the glasses on, and we're staring up at the sky.

And then suddenly the clouds part. And everything got dark, but everything also got quiet, except for the people who were going, look at that. Yeah. What do you make of that? I mean, this is what you cover, but there's also, you have to feel it too, right? Oh, absolutely.

No, it's astonishing. I saw my first total eclipse in 2017. I was in Wyoming for it. And I wrote a bunch of stories ahead of time about solar science, about the kind of things I was just talking about with the coronal heating problem and solar storms. And so I was like, okay, I know a lot about the sun. I know a lot about solar physics now. And I think I'm kind of prepared and I was not prepared. It was absolutely life-changing. I was just astonished at how incredible it was

to see that part of the sun that I had just been learning so much about, which was cool on its own, but just the like, like I understood why people thought it was religious or an omen or something in previous time periods and why was it life-changing for you why was it life-changing for me um i mean i wanted to see

more i got to see i got to see the one in 2024 also i i think i'm like at high risk of becoming one of those people who plans all their vacations around getting into the path of totality again. And it just takes, I think it's really special. We're the only planet where this happens. There are no other places in the solar system where the moon is exactly the right size to block the sun. So this is the only place in, definitely in the solar system, maybe in the galaxy, maybe in the universe. Like it's a pretty rare thing to have a moon this size. It happens to be exactly the right size to block out our central star. So that's really unique in itself, but also it's not going to be like that forever here. The moon is moving slightly farther away from the Earth every year, like two inches every year.

So eventually it'll be far enough away that it doesn't block the sun anymore. So we are living in a really lucky place in time, So eventually it'll be far enough away that it doesn't block the sun anymore. So we are living in a really lucky place in time, really a unique place in time in the history of the cosmos to be able to see this amazing thing. And that's really cool to think about. I think that's really special. It speaks to the value of what this project is. I mean, I asked about the practical elements,

but really it's about what you said, which is kind of wrapping your brain around the mysteries of the universe. That's what excites me. I think it can be both, but yeah, I'm here for the awe. Here for the awe. I love it. Lisa, thank you very much. All right. Thank you. Lisa Grossman is an astronomy reporter for Science News. For more CBC Podcasts, go to cbc.ca slash podcasts.