E9 – Inside the Boiling Center of the Solar System

The dark circle of Venus crosses the face of the Sun, seen in three wavelengths of extreme ultraviolet light. Credit: NASA/SDO/Peter L. Dove

At the heart of our solar system is an enormous, churning ball of hot plasma. The Sun blows a stream of charged particles over our planet, creating the solar wind. Sometimes the Sun flares bursts of x-rays, or burps bursts of charged particles, which can sweep over Earth and potentially create havoc for power grids, satellites, and GPS networks. There is weather in space, and it has more consequences for civilization than you might think.

Solar physicist Dan Seaton studies the Sun at the University of Colorado in Boulder and NOAA’s National Centers for Environmental Information, where he is working to understand the Sun’s atmosphere and predict when events on the Sun will affect the near-Earth environment. In this episode, Dan explains how space weather and space weather prediction is analogous to Earth weather—and how it is not—and how what happens on the Sun can affect us here on Earth.

Read a new paper by Dan and his colleagues about how solar flares disrupted radio communications during the September 2017 Atlantic hurricane relief effort.

This episode was produced by Liza Lester and mixed by Kayla Surrey. 



Episode Transcript

Lauren Lipuma: Do you remember that SNL sketch from the ’90s with Will Ferrell where he plays Harry Caray and he’s interviewing someone. [Laughter] He’s like, “What’s your favorite planet? Mine’s the sun.”

Dan Seaton:      [Laughs] I do now. I forgot about that one. Yeah, I totally remember that.

Lauren Lipuma: It’s like the king of planets. [Laughs]

Dan Seaton:      It is the king of planets. It’s like most of the mass and most of the energy in the solar system, and it determines the course of everything that happens. It’s the king of the planets.

Shane Hanlon:  [music] Welcome to American Geophysical Union’s podcast, about the scientists and the methods behind the science. These are the stories you won’t read in the manuscript or hear in a lecture. I’m Shane Hanlon.

Nanci Bompey: And I’m Nanci Bompey.

Shane Hanlon:  And this is Third Pod from the Sun. Hi Nanci.

Nanci Bompey: Hi Shane.

Shane Hanlon:  So, we’re talking about the sun, and I wanted to know what are you least and most favorite things about the sun?

Nanci Bompey: That’s a good one. That’s a good one. Let’s start with least.

Shane Hanlon:  Okay.

Nanci Bompey: Least is that when it’s hot in the summer, like it is here right now in D.C. it’s so hot you can’t even bear it.

Shane Hanlon:  That’s fair.

Nanci Bompey: Like when you walking to the office and you’re already drenched in sweat.

Shane Hanlon:  I’m with you.

Nanci Bompey: Least. Favorite though, favorite… a lovely sunset.

Shane Hanlon:  Oh. Look at that.

Nanci Bompey: Yeah, that is one of the … In our daily lives and thinking about the sun, that’s so beautiful. Sometimes the sunrise, the sunset, it really … Stop and take a look and take a picture.

Shane Hanlon:  That is so lovely, Nanci.

Nanci Bompey: And having a drink on a beach maybe.

Shane Hanlon:  All right, so today we wanted to bring in our producer, Liza Lester. Hi Liza.

Liza Lester:         Hi.

Shane Hanlon:  What have you got for us?

Liza Lester:         I talked to Dan Seaton. He’s a physicist who studies the sun and the sun’s atmosphere. He wants to understand the weather that’s coming from the sun, so not like heat waves, but things like solar flares and coronal mass ejections, or these big bursts of charged particles that come off the sun that can hit us here on Earth and cause problems with our power grids and our satellites and GPS systems and things like that.

Shane Hanlon:  I remember, there was a point where I had no idea what a coronal mass ejection was before I worked for AGU, so this will be exciting. [music] All right, so here’s the interview.

Dan Seaton:      I’m Dan Seaton. I’m a solar physicist. I work jointly at the University of Colorado in Boulder and at the NOAA National Centers for Environmental Information, where we really process all the data that comes down from various NOAA spacecraft that observe the sun and the heliosphere and the geosphere. The heliosphere is all the stuff from the sun out to the edge of the solar system, even beyond the edge of the solar system planets like Voyager, which has been traveling now for 40 years. It’s just leaving the heliosphere and going into inner planetary space. What happens is, the solar wind pushes out and forms a bubble of electrified magnetic fluid that fills all the space between the planets.

We talk about space being empty, but it’s not really empty. There’s stuff. There’s not much stuff but on big scales, on planetary scales, there’s a lot of stuff, and that’s the stuff that we’re interested in for space weather, because that’s the stuff that determines what’s happening around our planet that can interact with our magnetic field and cause a lot of interesting events.

I try to untangle, by looking at the images we produce, that mystery of how do you take forecasting the next step, and instead of just watching something happen on the sun, forecast that it’s going to happen before it happens, but we’re not there yet.

Liza Lester:         So, there’s actually weather in space. What is weather like in space?

Dan Seaton:      Yeah, obviously, it’s not the same as Earth weather. It is in a sense, it’s analogous to Earth weather, like, there are storms. There are fair weather days and bad weather days. The basic idea is that outflow from the sun, so charged particles moving at high speed, and the magnetic fields that get carried along with them, sweep out from the sun over the Earth and they can interact with the Earth’s magnetic field. They sort of shape the Earth’s magnetic field. You’ve seen comets with comet tails, and that’s the same phenomenon, pushing the comet tail away from the comet. As it’s shaping the Earth’s magnetic field, it sort of makes it into a tail and the solar winds buffeting the Earth on the Sun’s side and then stretching the magnetic field out into deep space on the other side.

Shane Hanlon:  Now, I’m just envisioning some sort of clip art illustration of magnets in space.

Nanci Bompey: Of the magnetosphere? Sorta.

Shane Hanlon:  I guess.

Nanci Bompey: Sorta.

Shane Hanlon:  Well, then, what is it Nanci?

Nanci Bompey: It’s the region up above, out in space above the Earth that is dominated by the planet’s magnetic field, by our Earth’s magnetic field, that’s generated deep inside the Earth.

Liza Lester:         So, this magnetic field, it’s stretching out really far around the Earth, above our atmosphere?

Dan Seaton:      Yeah, so on the sun side, it goes out to tens of thousands of miles and it provides us a bit of a protective shield from the oncoming solar wind, and on the other side it stretches out really far, because it’s pulled by this solar wind sweeping over us. It’s I don’t know how many of hundreds of thousands of kilometers into space.

When you get a lot of stuff, like a big solar eruption, then you get all sorts of crazy effects. When you get fast moving stuff, sometimes there are fast moving streams of the solar wind that sweep out at 700-800 kilometers a second. That induces, again, weird changes in the Earth’s magnetosphere that can put satellites in danger, that can put astronauts in danger, that can cause all sorts of secondary effects on the Earth, interfere with communications and cause power outages. We’re doing weather forecasting to try to prevent those things, just like the hurricane center does weather forecasting to try to … Well, you can’t prevent hurricanes. You can’t prevent these events either, but you can be prepared for them.

Liza Lester:         You were trying to find out when weather will happen on the sun.

Dan Seaton:      Yeah.

Liza Lester:         And how that will hit us here on Earth.

Dan Seaton:      Yeah, the hardest part is the sun, right? We don’t know anything about the sun. We know a lot about the sun but we’re just scratching the surface. Trying to say, “Okay, we’re going to look at the sun and we’re going to forecast some event on the sun,” is next to impossible. We see events and then what we can do is forecast how they’re going to impact the Earth or whether they’re going to impact the Earth, whether they’re going to propagate in the direction of the Earth or go harmlessly out into space, how significant they’re going to be, how energetic they’re going to be, and then that kind of correlates to the kinds of effects you can expect to see on the Earth. That’s space weather forecasting in a nutshell.

On Earth, you watch satellite video and you run these models. You say, “We see this little tropical wave forming off the coast of Africa and we can predict that in two weeks it might be a hurricane that’s going to be a problem.” But we don’t get that. The best case, you get a couple of days of suspicion that something could happen, and you still don’t know when or how.

Liza Lester:         How much warning are we talking about, here?

Dan Seaton:      Well, it’s not much. Some of the space weather effects that you get with a solar flare happen the moment that the light from the solar flare gets to the Earth, so that’s eight and a half minutes. The flare happens, eight and a half minutes later the light gets to Earth. That’s the first chance we have to see it. Instantly, it induces changes in the ionosphere that can cause radio blackouts and stuff.

Shane Hanlon:  Wait, hold on. Okay. We talked about the magnetosphere and the heliosphere, but what’s the ionosphere? I’m picturing a sphere of ions.

Nanci Bompey: I mean, not that far off, I guess, maybe? So, it’s the upper layer of the atmosphere and the gases in that layer get excited by all the radiation coming out from the sun and forms ions, so ionosphere.

Shane Hanlon:  All right.

Liza Lester:         The ionosphere is also cool because you can bounce certain kinds of radio waves off it, so like AM radio, which maybe you’ve never heard.

Shane Hanlon:  I have heard. I’m not that young, gee.

Liza Lester:         But also, short wave radio, the kind that ham radio operators use, they use that to bounce it off the ionosphere and that’s how you can hear it on the other parts of the world, get the radio waves to go that far. But, if the ionosphere’s really charged up, if things are really exciting on the sun, then it absorbs these radio waves instead of bouncing them back, and you can’t have radio that way.

Dan Seaton: The ionosphere sitting between us and all the satellites that do the GPS, so if the GPS signal is coming through an ionosphere that’s not what’s expected, it can get distorted, and so you can get a bad reading on your GPS. If you’re driving a car down the road and you get bad directions, it’s not necessarily that big of a deal, but planes rely on GPS and ships, and really importantly search and rescue relies on GPS. There’s a lot of significant risk if there’s interference there. There’s other effects. There’s old school navigation technology used by boats out on the ocean that bounces signals back and forth between antennas that are on the land. That stuff can get messed up. There’s a lot of potential impacts that you might not think of.

Then, there’s also effect that take a few days to get here from the sun. Those are easier to forecast. A power outage that is spawned by a space weather event, we usually have a pretty good idea that event is coming. We don’t always know how serious it’s going to be until we get here.

Shane Hanlon:  As an ecologist, I had no idea what the heck space weather was. It doesn’t rain in space.

Nanci Bompey: No, not really.

Liza Lester:         Let’s back up just a little bit first. Describe a flare to me. What does that look like?

Dan Seaton:      Yeah, they’re really dramatic, impulsive explosions. Flares, by their definition, are just brightenings on the sun. They’re very rapid brightenings that we see in X-Rays. But, we have images where we can really see the sun. You don’t just measure the amount of light, you see all this dynamic stuff. When we look at the sun, we can really see the actual sun’s magnetic field traced out in the plasma that’s in the sun’s atmosphere. The same thing that people see during a solar eclipse, we see with satellites all the time, not just during a solar eclipse. So, you can actually see the sun’s magnetic field and it changes configuration and you see big flows of material out into space. Flares are these really dramatic things, they set in and they kick stuff off into the heliosphere. That’s stuff that’s interesting from the space weather perspective.

These ordinary flares, they may be have a brief impact on the ionosphere. They get bright, but they’re a quick little blip. Something gets bright on the sun and it goes away in a few minutes or an hour or something like that. These big flares like the September flares reconfigured the sun’s entire atmosphere. They launched these shock waves that propagated all the way around the sun and bounced back off of each other and just scrambled everything. They threw huge amounts of stuff out into space. They heated parts of the sun’s atmosphere up to 30 million degrees, outrageous temperatures, temperatures that are hardly real, it’s so hot. What is 30 million degrees?

You get amazing data. You see so many effects, physical effects. You get a chance to test exotic theory. You know, these flares act as particle accelerators so this is like a physics lab at the same time as it’s a driver of space weather science research or whatever. The really big flares are really special.

Liza Lester:         What’s the biggest flare every recorded?

Dan Seaton:      Nobody knows. There was a really big flare in the mid-1800s, which was called the Carrington Event. It was so bright that you could see it in white light on the sun, which is not normal. That doesn’t typically happen. Flares, they make a lot of radiation but it’s generally in ultraviolet and X-Rays. To actually increase the brightness of the sun takes extraordinary energy. This thing touched of huge geomagnetic storms. These things set telegraph equipment on fire, telegraph offices. It caused auroras so far south. It never happened again.

Shane Hanlon:  All right, so this Carrington Event was a really big deal, but it happened a long time ago, almost a couple hundred years ago. Has anything like that happened since?

Nanci Bompey: Yeah, it has. It’s happened, and actually last September there was a pretty big event that happened.

Liza Lester:         Early September 2017. This was an exciting time for space weather, also a bit too exciting for some places on Earth.

Dan Seaton:      Yeah, so in September, the sun had been very quiet for a long time. Suddenly, in September, this big what we call an active region emerged on the sun. This big, complicated, mass of magnetic field and it causes sun spots, which are big dark things you actually see on the surface of the sun. It causes lots of radiation. This thing produced two huge solar flares, the biggest solar flares we’ve seen in more than a decade. Both of those solar flares just happened to occur on the sun at a time when the part of the Earth with the Caribbean was oriented towards the sun. If you think back to September, you remember it was this horrific hurricane season in the Caribbean. They just kept coming, big ones, bad ones. Hurricane Harvey had recently passed over and then you had Irma coming through, moving up through the Caribbean up to Cuba, and then Jose, which was a little further north.

A lot of these islands maybe had weathered the storm and now they’re trying to figure out what’s coming next. Do we have to prepare? They’re relying on radio networks run by amateur radio operators, for instance. Just as these hurricanes were sweeping over various islands in the Caribbean, big radio blackouts happened. Now, for emergency response, a big widespread radio blackout might not be that big of a deal because they don’t usually use the kind of communication technology that relies on this use of the ionosphere to bounce radio signals. But, imagine that you don’t have cell service because all your cell towers are either without power or knocked down. You don’t have telephone wires because they’re all knocked down. You don’t have electricity. You’ve gotta get messages through and sometimes you’ve gotta coordinate with disaster relief that’s on the mainland of North America. You’ve gotta get information to people like weather forecasters, who may not be able to get to their normal sources of satellite information or whatever.

It happened twice because there was one big flare on September 6 and then another one on September 10, and both of those caused problems. It’s a reminder that you’ve gotta look at the whole picture, including what’s happening on Earth and globally around the Earth in space, if you really want to understand the impacts of major national scale, potential disasters.

Shane Hanlon:  I had no idea that this was happening. We just live our daily lives and there’s solar flares everywhere.

Nanci Bompey: Yeah. Flares happen all the time.

Shane Hanlon:  All the time.

Nanci Bompey: Well, not all the time, but they happen.

Shane Hanlon:  Is there one happening right now?

Nanci Bompey: You just don’t even know about it.

Liza Lester:         What is making … Why does a flare happen?

Dan Seaton:      That’s a really good question. We sort of know. What happens on the sun is that the sun’s magnetic field is entwined with the plasma, the electrified gas that makes up the sun’s atmosphere, which we call the corona. Over time, the motions of the fluid in the sun, because the sun is not a solid body, it’s a fluid. It’s boiling and churning away, and each little motion of the fluid in the sun twists up the sun’s magnetic field. It’s a bit like if you twist up a rubber band and you twist it and you twist it, and then all of a sudden it kinks. This can happen in the sun’s magnetic field. It gets twisted and stressed and stores up all this energy, and suddenly, it reaches the point where it can’t maintain its equilibrium anymore and it can kink. It can actually kink. We have movies of this happening.

Or, it can explode out into space, where this deposits huge amounts of energy into the sun’s atmosphere. So much energy in big flares, it’s like if you add up all the energy produced by humanity since the beginning of humanity, it’s that much energy. More than that much energy in a matter of seconds. Big stuff.

This process can accelerate particles, so protons, electrons, that kind of stuff, to almost the speed of light. Those things, they generally go out in all directions, but they can come streaming towards the Earth. They can run into the Earth within a few minutes of the time we see the flare, to a few hours, depending on exactly how fast they’re going. And, those things are really hazardous. If you’re an astronaut outside of the International Space Station, you do not want to be there, when suddenly there’s all this radiation coming at very high energy. One of the next things that has to happen, if we see a big event, NASA would take some steps to protect astronauts, that kind of thing. It can also impact satellites, cause satellites to fail or to have weird computer problems or whatever.

After that, there’s stuff that gets blown off the sun. It’s not gradual. It’s thousands of kilometers a second sometimes, but it’s not the speed of light. This is a big cloud of magnetic field and ionized plasma that sweeps over the Earth, and then that’s when you get later effects like power outages and potentially currents can flow in railroad tracks and warp the railroad tracks. It’s crazy stuff as this magnetic field interacts with our own magnetism at Earth.

The simplest thing that can happen is it just compresses the sun side of the Earth’s magnetic field. Who cares, right? Well, if you’re somebody who operates satellites that expect to be inside this magnetic field and protected from all the crazy radiation and stuff that’s in inner planetary space, they can suddenly find themselves outside this field. In the worst cases, satellites fail because they get exposed to this radiation and they can build up electrical charges inside their bodies, and the discharge can damage components. If you lose your radio on your satellite then you can’t talk to it anymore. It’s effectively lost. That’s happened on occasion.

That’s the simplest thing and then, obviously, there’s more complex interactions that can happen. You can actually strip magnetic field from the front side of the Earth and move it to the backside of the Earth and then that magnetic field can interact with itself and cause a storm of its own. That’s often the process that actually generates the most damaging effects on Earth. It’s actually the Earth’s magnetic field being reconfigured, not totally unlike what happens on the sun when a solar flare happens. You store energy in the field and then you change its structure and then you release that energy, and then that causes all sorts of flows of particles that can lead to the aurora, which is space weather at its best, right? It’s really beautiful, it doesn’t have a lot of harmful effects, but it can also lead to these geomagnetic currents that can wreck power grids and that kind of thing.

Liza Lester:         It induces these currents and power grids that they’re just not prepared for?

Dan Seaton:      Yeah, that’s the idea of space weather forecasting. They can be prepared.

Shane Hanlon:  And, I assume they are preparing.

Nanci Bompey: Yeah. That’s why this science is so actually really important. If you are a power company, running a power grid, you know about space weather. You’re watching, you’re working with the science and the space weather forecasters to understand what’s coming and how you can prepare your grid in case something bad comes our way.

Liza Lester:         Is there an alert system like we have for Earth weather?

Dan Seaton:      Yup. It’s just like we have for Earth weather, like with hurricane categories or whatever, and severe storm watches and warnings, flash flood watches and warnings, all that stuff. They have a parallel system that anticipates the primary effects of different kinds of space weather effects, and categorizes them on a scale of one to five, where one is like, “Don’t worry about it,” and five is like, “This is a big deal. You’d better take precautions.”

The Space Weather Prediction Center is staffed by two people all the time, around the clock, just like any weather station, weather service office. They sit in a room with 40 computer screens and the screens are showing all the information we have available about what’s happening on the sun, between the sun and the Earth, near the Earth. You know, there’s ground based sensors on the Earth that can tell us some things. There’s satellites in Earth orbit that tell us some things. They’re watching, what does the sun look like? Is it active? Is it not active? Do you see a flare? Where is the flare? And then, do you see stuff going out into space that could be dangerous to Earth or not?

And then, there’s some satellites between the Earth and the sun, and they’re watching little timelines that, “Oh, yeah. This thing sees a big jump in the speed of the solar wind,” which is one of the best predictors for whether there’s going to be a geomagnetic effect. That, also, is the only bit of warning that you get that a big geomagnetic storm’s going to happen, because the satellite that looks at it is a million-ish miles away from the Earth.

Liza Lester:         So, it’s almost like the wind coming in before a big thunderstorm?

Dan Seaton:      Yeah. You see this and then you say, “Okay, at the speed this is going, we have 30 minutes before this is going to reach the Earth, or an hour before this is going to reach the Earth, so we’d better be prepared.” Then, in addition to all the data, they have models. The models aren’t quite as sophisticated yet as the Earth weather models, but they do a pretty good job of telling you if something comes off the sun, is it likely to hit the Earth or miss the Earth, that kind of thing. They’re just on the phone. Airlines will call them up and say, “It looks like the sun’s a little active. What’s your opinion?” They give an opinion and they write forecasts. I think they talk daily with NASA for planning activities on the International Space Station. I think it’s a pretty busy and stressful job, actually.

There have been historical episodes where flares were misinterpreted as nuclear strikes. I don’t know that much about them, but you definitely want to know the difference between an electromagnetic pulse from a nuclear weapon and a flare, or bad things could happen. This is one of the services that the Space Weather Prediction Center provides. They let you know. This was just a flare, there’s no need to panic. I don’t think space weather’s the kind of thing that causes the apocalypse. It can cause a big hassle and an expensive problem, but I don’t think it’s one of those things that’s going to threaten civilization as we know it. But like that, it’s a big expensive problem that can be a real headache for civilization, and we’re working on solving that.

Shane Hanlon:  So, Nanci, what are your views on Nicholas Cage?

Nanci Bompey: I don’t have a view on Nicholas Cage.

Shane Hanlon:  Everyone has a view on Nicholas Cage.

Nanci Bompey: I don’t know.

Shane Hanlon:  Did you ever see Knowing?

Nanci Bompey: No.

Shane Hanlon:  Okay. Oh my goodness. So, it’s bad but it’s good. The world’s ending because of solar flares but it’s actually because of aliens and the aliens are stealing the children to put them on another planet to help them build a better life. It’s Nicholas Cage and Rose Byrne.

Nanci Bompey: But they think it’s a solar flare?

Shane Hanlon:  No, it is a solar flare. The world ends.

Nanci Bompey: But it’s aliens?

Shane Hanlon:  Spoiler alert.

Nanci Bompey: Aw, thanks. Guess I’m not going to go see that one.

Shane Hanlon:  I know. You’re welcome. I just saved you the time. All right. So, that’s all from Third Pod From the Sun, but stick around to see how Dan thinks the world is actually going to end.

Nanci Bompey: But first, special thanks to Liza for bringing us this episode and, of course, thanks to Dan for sharing his work with us.

Shane Hanlon:  And the podcast is also produced with help from Lauren Lipuma, Josh Speiser, Olivia Ambrogio, and Caitlyn Camacho. And thanks to Kayla Surrey for producing this episode.

Nanci Bompey: AGU would love to hear your thoughts. Please, write and review us on iTunes and listen to us on your favorite podcasting app.

Shane Hanlon:  Now, Liza.

Liza Lester:         So, we have this new question we’re asking everyone and it is, “How do you think the world is going to end?”

Dan Seaton:      As a solar physicist, I think what’s going to happen is the sun is going to increase in brightness over the course of its lifetime. It very gradually is getting brighter and brighter. In about a billion years, it’s going to be bright enough that the incoming energy from the sun is going to be too much for the Earth to be habitable anymore, so we have a billion years and then we’ve gotta move somewhere else. We can move to Mars maybe. Then, a few billion years after that, maybe at five billion years from now, the sun will run out of fuel, hydrogen. So, normally what it does, it fuses hydrogen into helium in its core and that’s what gives it its energy.

When it runs out of hydrogen, it’s going to start fusing heavier elements and it’s going to change the pressure equilibrium inside the sun, and it’s going to blow up really big, so big it’s going to sweep up Mercury and Venus and probably the Earth, which will already be uninhabitable. But, our new civilization, which has moved to Mars, is also going to be in trouble, so then we’re going to have to think of another solution. That’s my prediction. I try to be optimistic. I think we’re problem solvers. I think there’s a lot of things that could go wrong for us, but I think we’re going to solve them. We have solved problems in the past, and space weather is one of those things.

Similarly, other problems on Earth, I think we’ll work to solutions, but there’s some things you can’t control, and one of them is, eventually the sun’s going to change, so maybe we’ll make it a billion years, but then we’re going to be out of time. We’re going to have to leave.

Shane Hanlon:  Thanks all and if the world doesn’t end, we’ll see you next time.

1 Comment

  1. Paul Seaton on September 10, 2018 at 4:14 am

    Very informative! Thanks, Dan! I’m impressed.
    (Full disclosure, this comment is from his dad.)

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