Ep. 321: Solar Flares

Sometimes the Sun is quiet, and other times the Sun gets downright unruly. During the peak of its 11-year cycle, the surface of the Sun is littered with darker sunspots. And its from these sunspots that the Sun generates massive solar flares, which can spew radiation and material in our direction. What causes these flares, and how worried should we be about them in our modern age of fragile technology?

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This episode is sponsored by: Swinburne Astronomy Online, 8th Light

Show Notes

  • Solar Flares — NASA
  • What Will Happen When the Sun’s Magnetic Poles Reverse? — Universe Today
  • How Apollo Astronauts Avoided a Deadly Solar Flare — Science Focus
  • Solar Flares: How much does it take to be X-Class? — NASA
  • Carrington Flare — NASA
  • The Quebec Blackout — the Day the Sun brought Darkness — NASA
  • Come On Eta Carinae … Explode Already! — UT
  • Your Guide to When, Where and How to see the Aurora Borealis — UT
  • SpaceWeather.com
  • Ep. 163: Auroras
  • Ep. 238: Solar Activity
  • Transcript

    Transcription services provided by: GMR Transcription

    Dr. Pamela Gay: This episode of Astronomy Cast is brought to you by Swinburne Astronomy Online, the world’s longest running online astronomy degree program. Visit astronomy.swin.edu.au for more information.
    Fraser Cain: Astronomy Cast episode 321: Solar Flares. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain. I’m the publisher of Universe today. And with me is Dr. Pamela Gay, a professor at Southern Illinois University, Edwardsville, and the director of Cosmo Quest. Hey Pamela, how are you doing?
    Dr. Pamela Gay: I’m doing well. How are you doing, Fraser?
    Fraser Cain: Good. I’m just returning back from a week of recording video down at the YouTube LA studios. So, we got tons of good stuff, and that’ll all be appearing in the YouTube feed on Universe Today over the next couple of months, probably.
    Dr. Pamela Gay: And, you got to experience what it’s like to record in someplace that is not only warm – because I know we both freeze to death in our studios – but also had all the bells and whistles, which is kind of awesome.
    Fraser Cain: Yeah, it was great. It was just amazing to be able to use all of this great gear, cameras, lighting equipment, yeah. It was great, and I really appreciated their assistance as well, when we didn’t know what we were doing, which was most of the time.
    So, hopefully this’ll allow us to provide more professional recording type stuff in the future.
    Dr. Pamela Gay: It’s a goal.
    Fraser Cain: Just as a reminder to everyone that we record Astronomy Cast every Monday at 12:00 p.m. Pacific, 3:00 p.m. Eastern, as a live Google+ Hangout on air, and you can find that video in a bunch of places. Over on Universe Today we post it, on Google+, on YouTube, on Cosmo Quest. So, if you want to watch us live, and then interact and ask us questions, you can do that every week Monday, except for next week when we’ll be recording at a different time. But, normally every Monday.
    All right, let’s get rocking with the episode.
    Dr. Pamela Gay: This episode of Astronomy Cast is brought to you by 8th Light Inc. 8th Light is an agile software development company. They craft beautiful applications that are durable and reliable. 8th Light provides disciplined software leadership on demand, and shares its expertise to make your project better. For more information, visit them online at www.8thlight.com. Just remember, that’s www.8thlight.com . Drop them a note. 8th Light; software is their craft.
    Fraser Cain: So, sometimes the sun is quiet, and other times the sun gets downright unruly. During the peak of its 11-year cycle, the surface of the sun is littered with darker sunspots, and it’s from these sunspots that the sun generates massive solar flares, which can spew radiation and material in our direction. What causes these flares, and how worried should we be about them in our modern age of fragile technology?
    So yeah, let’s talk about solar flares. And, you could not have timed your selection of this episode any better because we are just experiencing a gigantic sunspot cluster, AR 1890, and it has been firing off material in our direction.
    Dr. Pamela Gay: It is flare happy, and this means if you have any flights upcoming, make sure you figure out which side of the aircraft is gonna be the north side of the aircraft if you’re flying after dark. Because, these aurora are absolutely amazing to watch from an aircraft, and you couldn’t get a better time to see them.
    Fraser Cain: Yeah, absolutely. It’s an absolute treat to – especially because a lot of, like, if you’re going to fly from, say, New York to Europe, you’re going to go a great circle route, you’re going to go past Greenland, and you’re going to get a view. So absolutely, if you’re going that way, try to take the left side of the aircraft.
    Dr. Pamela Gay: Chicago to Beijing, right side of the aircraft.
    Fraser Cain: Yeah, so figure that out.
    So okay, so let’s talk about solar flares then. So, what is the series of processes that lead up to us seeing a solar flare?
    Dr. Pamela Gay: It’s basically a fairly simplistic process to try and explain, and extremely complicated to mathematically model. What’s happening is, as our sun is working on turning its magnetic fields inside out, as it’s working to make its north magnetic pole its south magnetic pole or its south its north, however you want to look at it, it reaches this phase that what we call is solar maximum. And, during solar maximum, a bunch of the magnetic field lines, the lines of force along which particles flow, end up forming helixes that pop out through the surface of the sun. And, where they pop out, we see these darker regions, these sunspots, or solar sunspot complexes.
    And, these field lines, they contain vast amounts of energy. And sometimes these field lines realize that, “Hey, we’ll be at a much lower energy if we break the top part of our coronal loop,” this loop of helixed magnetic lines that come out the surface of the sun and basically form giant arches. “If we break off the top section, set it free, and re-connect closer to the surface of the sun.”
    During these magnetic field line reconnection processes, all of that energy that was trapped in that magnetic field, that tube of plasma, suddenly gets released. It becomes kinetic energy. It becomes thermal energy, and all of that goes firing off. And, in some cases it gets fired off straight at us.
    Fraser Cain: You know what’s one of the best experiments that you can do to sort of show this process is take spaghetti and bend it, and break it, and I forget the exact physics that make this happen, but you will always get a chunk of spaghetti flying off.
    Dr. Pamela Gay: Stress and strain.
    Fraser Cain: Yeah, it never just breaks. It always fires off a chunk of spaghetti out, and you’ll get one or two pieces that will head off in one direction just because of the physics involved, the forces and the stresses and stuff. So, you can imagine you can fire chunks of spaghetti at your friends, and you say, “I’m just making solar flares. It’s just a science experiment.”
    Right, so you get these disconnections and reconnections, and then you get this release of energy. And so what kind, what order – how much energy are we dealing with here?
    Dr. Pamela Gay: This is one of those things that, when I started looking up the energies, it was really kind of mind-numbingly large. I’m in the process of pulling up the numbers, so if you see me looking in strange directions, it’s because I want to get this right.
    So, it’s the equivalent of millions of 100 megaton hydrogen bombs exploding all at once. It’s a little less than 10 percent of the sun’s solar output per second. So, when you start thinking about that, that’s a pretty huge number. That’s, like, earth destruction number. But luckily, we’re far away.
    Fraser Cain: Yeah, 10 percent of the sun’s entire output for a second is released in one little spot.
    Dr. Pamela Gay: And when this energy is released, it fires off protons, electrons, basically ionized particles, things that have charge. And, this is where it gets interesting. Because, a charge in motion generates its own magnetic field. And, those charges in motion end up hitting our own Earth’s magnetic field.
    Fraser Cain: So, how long does this process take? Like, say you’ve got these magnetic field lines are starting to twist up, and then you get that event. How long does that whole process take then to sort of get to the Earth?
    Dr. Pamela Gay: Well, it’s only a few seconds for the whole arch, the loop of twisted magnetic field lines, to break and reconnect. But then, the light travels towards us so that we can see this happening. That travels at us, well, at the speed of light. So, about eight minutes later, we see what has happened. Some of the satellites that are closer to the sun than us will see it first, but we still have to wait for their information to get to us at the speed of light. So, we’re not gonna find out about this in anything less than a little over eight minutes.
    But, then we have to wait for the particles themselves to get to us. And the particles, luckily, are not traveling at the speed of light. In some cases, they’re traveling faster than others, but in general, you’re looking at several hours. Now, where it gets a little bit squirrely is our best indication that, “Oh, oh dear, the Earth is about to get hit,” comes from a set of geostationary satellites. These are the GOES satellites, which highly amused me with their naming scheme. They’re the Geostationary Operational Environmental Satellites.
    They’re constantly watching both down at the Earth to measure weather, and before they get launched, they’re named letters. So GOES A, GOES B, GOES G, last year they launched GOES P, which is my most favoritely named satellite. But, once they’re in orbit –
    Fraser Cain: Giggle.
    Dr. Pamela Gay: Yeah, yeah, you have to giggle at that one. But once they’re in orbit, they get renamed with numbers. So, we’ve had GOES 1, GOES 2, GOES 3 orbiting the earth.
    And, these satellites, being up at geostationary orbit, they’re significantly higher up than the space station, than the space shuttle, or was the space shuttle, now Soyuz, and they detect the particles coming towards the earth a little bit sooner because they’re further out. And, they can provide the astronauts all of about 15 minutes’ warning that they need to seek shelter, something really bad is coming.
    Fraser Cain: Now, why would the astronauts need to seek shelter?
    Dr. Pamela Gay: Well, these high-energy particles, they can cause severe damage when they start hitting your molecules. This is a form of radiation. This is actually one of the major reasons that we’re worried about keeping our astronauts safe if they go on a mission out to Mars. Here on the surface of the Earth, we’re well inside the Earth’s magnetic field. We have a big atmosphere above us. All of these different things work to either redirect the streaming particles, or to protect us from the high energy photons that they release.
    We’re safe on the surface. The astronauts are up above a lot of the protection, and they can get zapped in ways that could increase the probability of cancer, and otherwise harm their DNA.
    Fraser Cain: Now, is this an issue for the astronauts on board the International Space Station? Because, it orbits much lower, right? And it’s protected by our magnetosphere.
    Dr. Pamela Gay: It’s protected by our magnetosphere, but it’s not protected by our atmosphere. So, if you have X-ray photons, those are quite happy to go through things like, oh, fiberglass. So, they’ll get stopped by metal shielding. They’ll get stopped by other things. But, the highest energy photons that get released, those are going straight for the astronauts through the outer shell of the space station in some areas. There are regions that they can go into that are safer, and that’s where they go when there’s really bad events.
    Fraser Cain: But, the real risk is for the folks who would leave the Earth’s orbit and go to the moon, or Mars, or things like that, right? I mean, they’re really exposed.
    Dr. Pamela Gay: Right. So, it’s the space between here and Mars that is the most dangerous. If you’re on the moon, you can go under the surface. If you’re on Mars, you can go under the surface. You always have some hole in the ground that you can climb into if you need it.
    Between here and Mars, you want to have as lightweight a spacecraft as possible, which means you’re probably not going to have a big lead shield all around you. And, you’re probably not going to have a big water layer between you and the outside of your spacecraft. All of these extremely heavy things can help to protect you from the radiation, but they weigh too much to support taking them all the way to Mars.
    Fraser Cain: Yeah, and I know that the astronauts, when the astronauts went to the moon, they actually were really fortunate that they avoided some of these major flares. They were there when it was quiet. But before and after, there were some pretty bad flares.
    Dr. Pamela Gay: Yeah, there was at least one Apollo mission where it was just a couple of weeks before and a couple of weeks after, there were some big X class flares that could have seriously harmed the lives of the astronauts. And, at that point, we didn’t necessarily have all of the GOES satellites giving us early warnings.
    Fraser Cain: Yeah, this is a really new development, is that we have this monitoring system, so that we can see these flares on the sun and then take action. I guess you see the radiation and then take action before the particles arrive. You’ve got this gap, right?
    Dr. Pamela Gay: And in all honesty, GOES wouldn’t have helped with the Apollo missions because geostationary is inside of the moon’s orbit. But, we also have things like Solar Dynamic Orbiter, we have a whole series of satellites out there monitoring the sun. The stereo missions, the numbers just go on and on.
    Fraser Cain: Yeah, and the worse the flare, the less time you have, right? Because there’s more energy boosting the particles out.
    Dr. Pamela Gay: Well, it’s a combination of – yes. There’s more energy how it’s released, but you can spread that energy over a larger area, or you can concentrate it in a smaller area. So, when you use words like “big,” that’s not the clearest word. Because, you could have this big, giant thing, but the flux over any small area is much less.
    So, when you start trying to figure out, “Is this a big flare? Is this a small flare?” What we actually look at is the flux over a set region as measured by the GOES satellites at the distance of, well, geostationary orbit above the earth.
    Fraser Cain: Well, they have a method for classifying flares, right? They have an actual M, X, different kinds.
    Dr. Pamela Gay: Right, and this ends up being – so, they make estimates of how strong they think the different flares are going to be based on what they see, and then they classify the flare finally by how strong it is when the energy hits the Earth’s atmosphere. So, this is where you start looking at watts per square meter. They look at it in 100 to 800 pycnometer wavelength of the light that’s coming, and it’s actually measured by satellites in geostationary orbit of the Earth.
    So, they do make estimates based on what they see. But, the final measurement comes from the flux it’s hitting at geostationary orbit.
    Fraser Cain: And so, what is the measurement system? Like, we have like with earthquakes, right, you’ve got the, I guess before it was the Richter scale. There’s a new scale. But you’ve got tornado scales, you’ve got hurricane scales.
    Dr. Pamela Gay: Right. So just like with the Richter scale and just like the magnitude system we use with our eyes, this is a logarithmic scale. A is the wussiest. It gives off 10 to the minus seven watts per square meter. So, if you imagine a millionth, basically, of a one watt Christmas tree light, or a 10 millionth of a Christmas tree light, that’s how much light you have covering a square meter.
    Then 10 to the minus seven to 10 to the minus six, that’s a B class flare. And then the X class flares are ones that are 10 to the minus four watts per square meter.
    So, the amazing thing is that these things are not even giving off as much light as your faintest Christmas tree light, with its energy spread out over an entire square meter. But, when you start looking at the size of the Earth’s atmosphere, there’s a whole lot of area to be collecting all of that wattage, and it adds up. And all of those moving particles, they create changes in our Earth’s magnetic field.
    And, here’s where it starts to sound a little bit like turtles all the way down. So, you have moving particles coming from the sun. Moving particles generate magnetic fields. The magnetic fields from these particles cause variations in the Earth’s magnetic field. When the Earth’s magnetic field varies, you end up creating, well, in this case, currant, and that currant just happens to be in places like, oh, the power grid on the planet Earth.
    Wires are very good at carrying currant that’s generated by changing magnetic fields.
    Fraser Cain: So, what’s the most powerful flares that are sort of possible?
    Dr. Pamela Gay: The most powerful one that’s been measured so far is one that occurred – it’s called the Carrington flare. And, it occurred in the 1800s. In fact, it occurred on September 1st, 1859. And, there was a well-to-do scientist, a gentleman scholar you might say, 33-year-old Richard Carrington. And, he was, at the time, England’s foremost solar astronomer.
    And, he got up in the morning, and he was happily making his daily measurements, and there was this amazing sunspot cluster that, well if you look at the image, science.nasa.gov has them posted, and they’re stored by the Royal Astronomical Society. It looks more like a sea serpent or a whole bunch of slugs come together than like your classic single or double sunspot. It’s this amazing system.
    And, at 11:18 a.m. in the morning, he saw where the sunspot that he was sketching was suddenly flashed out with white light. And, that is significant because the majority of the energy given off in solar flares isn’t in white light. It’s in much higher wavelengths of light that aren’t visible to the eye. He saw a white light flare in his projection of the sun. And, he went to get a friend to witness it with him so that it wasn’t a lone account, and just five minutes later when he returned with someone, it was already starting to fade away.
    So, this amazing flare that was visible in white light, the next day created aurora borealis in Aurora, Australia, that reached all the way down to places like Jamaica and Cuba, places that normally never get to see this. So, this was the biggest flare that anyone has ever seen. And what’s kind of remarkable is if you take arctic ice cores or Antarctic ice cores, you start to see the history of solar flares recorded in the ice, and this is a once in 500 years’ event. No other flare in the 160-some odd years of visual observations or in the 500 years that we can measure through the ice has compared to this. And, in fact, it’s more than twice as powerful as the next brightest flare.
    Fraser Cain: Well I know the one that was fairly recent, we had one a couple of years ago, and it was like an X 28 flare.
    Dr. Pamela Gay: Right. That was the one that took out the power grid. That was a kind of awesome one.
    Fraser Cain: Yeah, and I heard that that one in the 1850s was like an X 40.
    Dr. Pamela Gay: Right. So, the one that you’re talking about is the March, 1989 geomagnetic storm. So, it makes us old that that seems like just a few years ago.
    Fraser Cain: Yeah. Well, I remember it happening. We had a big problem in Canada. We had this –
    Dr. Pamela Gay: It’s referred to as the Quebec blackout. So, this was when we learned for the first time, really – and, we knew from the 1859 event because it actually caused telegraph wires to set paper on fire, and they disconnected all of the batteries from telegraphs, and they were still able to send messages through the wires. But, this was the first modern history one where everyone was relying on electricity and this happened.
    So, the problem was that the power grid in Quebec was running at pretty high capacity. And, you can only send so much electricity through the wires before they start to do things like melt, like change length, stretch under their own. So, as they stretch, as you heat them up, they’ll eventually even just break. And, so in this case, they overpowered the Quebec power grid and sort of took out power to a large chunk of the Northeast Corridor.
    Fraser Cain: And, so this is, I think, the big issue. And, when you think about these horrible blasts of radiation coming from the sun, and you wonder, ‘Are we going to get irradiated?” The answer is no, thanks to our atmosphere. But, it’s this impact on our technology that’s the problem.
    Dr. Pamela Gay: Right. And, you have to worry about what happens if this sudden blackout happens and it’s winter and there’s people relying on electronic heat. We learned during the more recent 2003 blackout, which was caused by tree limb on a wire and a faulty alarm going off, that if you knock out the power for the Northeast, Canada and the United States, it can take as long as two days to get that power back on.
    Well in the summer, you just sweat a lot. But in the winter, that can become deadly because not everyone has fireplaces anymore.
    Fraser Cain: Yeah, Quebec is not a nice place in the wintertime without power.
    Dr. Pamela Gay: Right, and so we have to really start worrying about northern China, about northern Russia, about Scandinavia, Iceland, and all through Canada, Alaska, and the northern United States. And, it’s in these northern extremes, where the winter is so much worse, that our power grid is the most fragile.
    Fraser Cain: But, I mean, it’s more than that. I mean, we’ve got these telecommunication systems, we’ve got communication satellites. We’ve all got these computers that sit in our pockets now.
    Dr. Pamela Gay: And these X class flares can take out a satellite now and then if they’re particularly strong. All of that X-ray energy – yeah, that can knock out sensors.
    Fraser Cain: Yeah, so I think that’s the big risk. Now, our sun is a – what is it? A minor dwarf star. Is it a G dwarf star?
    Dr. Pamela Gay: It’s a G star, yeah. Main sequence, everyday star.
    Fraser Cain: But, the solar flares change with the different kinds of stars. And, we’ve talked about red dwarf stars. They have totally different kinds of flares, right?
    Dr. Pamela Gay: Right. And in fact, depending on what phase a star is in, they’re all generally called flare stars, but they have different sub classes. And one of the nastiest stars for a prolonged period is those red dwarfs. When they’re quite young, they’ll go through a couple billion years of giving off massive blasts of X-rays, such that any planet that was in what would otherwise be known as their habitable zone would simply get irradiated into oblivion.
    And, that’s long enough that your planet is formed, is sitting there, and any life on it gets destroyed before the system really settles into existence.
    Fraser Cain: And then, what about some of the bigger stars, like the big Eta Carinae, things like that?
    Dr. Pamela Gay: So Eta Carinae, it’s not so much a flare star as it’s undergone various nova over – Well, it underwent one big, bright one in the 1800s. But, we have other things like UV Ceti stars. These are stars that, when you watch them, they give off these sudden brightening moments that are quiet brief. And, we believe that these are flares just like our sun experiences.
    We’re able to observe sun spots on other stars. We have no reason to believe that these parallel brightenings aren’t a parallel event caused by flares. So, it’s neat to see that the physics that applies to our sun applies at different scales in other types of stars all across our universe.
    Fraser Cain: So, we’ve done a whole show on the aurora borealis and aurora Australia. So, if you want to go back and get more information about how to see the northern lights and the mechanism that’s going on there. But just a refresher, if people wanted to see the northern lights thanks to these flares, and especially now that we’re in this solar maximum time, this is your chance.
    So, what should people do to sort of get up to speed on what’s going on? And there’s great new technology now.
    Dr. Pamela Gay: Well, the best thing you can do is keep an eye out on spaceweather.com. That website will always keep you up to date on where the best auroras are likely to happen. And if you find out you’re in a region where there’s a likelihood of seeing aurora, get out of the city lights. Find someplace that doesn’t have that much light pollution, or make sure the light pollution is on the southern horizon and then look north. And watch for streaks, for curtains, for all sorts of amazing, glowing movement along the horizon, and sometimes all the way up to the zenith. It’s really beautiful to watch.
    Fraser Cain: Yeah, I mean, even since we’ve been recording this show, the technology for tracking them and predicting them has gotten a lot better, and that information has even really gotten disseminated out through the internet. So now there’s apps you can use, and maybe people could make some recommendations of what they’ve used. But, there’s apps you can use that will give you predictions when it’s time to go see some aurora. So, it’s really amazing now what’s possible. So, if you live anywhere north of, I don’t know, Chicago? Even more south than that.
    Yeah, you stand a chance of being able to see one, especially during this solar maxim.
    Dr. Pamela Gay: The best shot is always in Scandinavia and in Alaska, but really anyone from about Boston, London, northward, you’re probably good to go. But, this is where I’d say also go back and listen to our show on coronal mass ejections. Because, solar flares do have a bigger, badder brother.
    Fraser Cain: Yeah, absolutely. Awesome. Okay, well thank you very much, Pamela.
    Dr. Pamela Gay: Thank you.
    Fraser Cain: Thanks for listening to Astronomy Cast, a non-profit resource provided by Astro Sphere New Media Association, Fraser Cain, and Dr. Pamela Gay. You can find show notes and transcripts for every episode at astronomycast.com. You can email us at info@astronomycast.com . Tweet us @astronomycast. Like us on Facebook, or circle us on Google Plus. 
    We record our show live on Google Plus every Monday at 12:00 p.m. Pacific, 3:00 p.m. Eastern, or 2000 GMT. If you missed the live event, you can always catch up over at cosmoquest.org. If you enjoy Astronomy Cast, why not give us a donation? It helps us pay for bandwidth, transcripts, and show notes. Just click the donate link on the website. All donations are tax deductible for US residents. 
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    [End of Audio]

    Duration: 29 minutes

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