Violent solar eruptions predicted for 2013
The number of sunspots is an indication of the intensity of violent eruptions from the surface of the sun. A spike in activity occurs in cycles of approximately 11 years. 2013 is predicted to be a big year for these solar events. Known as coronal mass ejections, they spew out plasma and magnetic fields into space. It washes over planets energizing the Earth’s magnetic field, producing charged particles and phenomena such as the northern lights. Currents can be induced in electrical circuits. Problems can occur with satellites. In extreme cases, they can even be destroyed. There could be interruptions to GPS and aircraft operations. It is estimated $2 trillion of the world’s economy is based on satellite transactions. Luckily, astronomers can see these eruptions lift from the sun’s surface, and their speed can be measured. Typically they take 1-3 days to get to the Earth. So warnings can be issued.
Lucie Green: From the surface of the Earth we get to see the visible light emission of the Sun but actually there is so much more to it than that. So what I do and what my colleagues do is put telescopes into space above the Earth's atmosphere, and this means that then you can see other wavelengths of light given off by the Sun. And for me the most useful information is carried by X-rays given off by the Sun and ultraviolet light given off by the Sun. And certainly most of the ultraviolet and all of the X-rays is blocked by the Earth's atmosphere.
Robyn Williams: Why isn't the signal just so strong that these headlights get blasted?
Lucie Green: Actually there's not very much X-rays and ultraviolet light coming from the Sun, it's a small fraction of the overall output. So we have to make sensitive detectors to pick it up, but there is still plenty for us to see. But yes, so going into space we can create these amazing pictures of these structures in the Sun's atmosphere. And it turns out that when you look at the surface of the Sun it's fairly uniform except for these dark spots that we call sunspots. When you look at the atmosphere, which contains really hot gases, the gas is shining very brightly in ultraviolet light and in X-rays, but they take on all these beautiful sinuous structures, that's because the Sun's atmosphere is full of magnetic fields, and the influence of the magnetic fields creates all these fantastic shapes.
Robyn Williams: So you're looking for these structures. How big are they, say, compared to the size of the Earth?
Lucie Green: They are immense, they are many, many times the size of the Earth. When you put the Earth to scale next to them, you feel completely dwarfed. And from time to time these magnetic structures erupt into the solar system, and when that happens they expand, so they become even bigger, millions of kilometres in size, the Earth is completely dwarfed by them. And if they wash over the Earth they can take maybe a day or half a day to flow over us because they are such vast structures.
Robyn Williams: One of the reasons we're talking about this now is that 2013 is supposed to be the year of extra special violent eruption. How do you know that's going to happen?
Lucie Green: When we look at the Sun we see it has a cycle, and this is one of the great achievements with the first telescopes. The first thing we saw was that the sunspot number varied over roughly 11 years, so it rises and falls and rises and falls. And with that goes associated activity, for example like these eruptions that we call coronal mass ejections. So by watching the sunspot number, we know that we are approaching a time of maximum activity, and that is currently predicted to be around 2013.
Robyn Williams: 2013, so we can expect some of those huge eruptions coming, and of course they flow across with space weather to the Earth and interrupt in all sorts of dramatic ways. Give us some examples of how they do that?
Lucie Green: When these magnetic eruptions hit the Earth, they interact with the Earth's magnetic field and they can energise it. They can accelerate charged particles from very high heights down to the top of our atmosphere, producing the Northern Lights and the Southern Lights, so a spectacular visible manifestation of space weather. But then there are invisible things that happen as well. So currents that get set up in our atmosphere can also have currents induced at ground level which flow through our electricity networks causing problems, they can cause transformer damage and blackouts, which is not good, you don't want your electricity to be lost. Higher up in the atmosphere we have problems or can have problems with our satellites. Certainly satellites can have malfunctions, they can be totally destroyed by space weather.
Robyn Williams: That's billions of bucks worth of damage.
Lucie Green: Absolutely, yes. So we rely so much on space science technology now, whether it is for your mobile phones, whether you're looking at GPS positioning, GPS satellites also give us timing stamps that bank transfers use. I think 6% of the GDP of the developed world relies on services provided by GPS satellites. And if they go down because of a space weather event, that's a huge loss to the economy.
There has also been some interesting research recently about the effect at the altitude of aircraft. So in Europe, airline workers are almost classified as radiation workers now because of these high-energy particles in the Earth's magnetic field and atmosphere during a space weather event. So you want to monitor the health of the people on board the aircraft, but also the sensitive electronics of the aircraft can be disrupted as well. And not only that, you can lose your radio communications because of changes to the atmosphere during a space weather event. So then you need to reroute your aircraft (in particular I'm thinking of the ones that fly near the poles) to bring them down to lower latitudes so that you can pick up satellite communications. That's assuming that all your satellites are working okay.
Robyn Williams: Of course the Earth is protected by its own magnetic field and also by its atmosphere, vis-à-vis other planets such as Mars. But your job of course is to spot one of these big ones going up, one of these huge structures, and you can give us a warning. How much warning?
Lucie Green: The good thing is that these things take a certain amount of time to travel towards us. You're absolutely right, we see the structure lift off from the Sun, and then we'd be looking to see how fast it's going, and then we can work out how long it would take to travel the 150 million kilometres from the Sun to the Earth. Typically they would travel between one day and three days, so we have some warning.
Robyn Williams: If there is a really big one, and I seem to remember the date, 1859, which happens to be when Origin of Species was published by Darwin, 1859...what if a really, really big one like that happens?
Lucie Green: That is the burning question at the moment; what happens? So fortunately the 1859 event happened before we had all the current infrastructure, but it also means we don't have much data to go on to really work out what the equivalent would be today. But we do think this 1859 event, the Carrington event, is the largest event on record, and we use that as an upper limit of what we think the Sun could do today. If that did happen, worldwide the prediction is that there would be...gosh, something like US$2 trillion worth of damage globally produced by this kind of event. Forecasting it is very difficult because you need probably so many things to come together to produce this perfect solar storm, including the details of that particular coronal mass ejection itself, but also events that might have happened previously to precondition the Earth's magnetic field to mean that when this event arrives it becomes particularly effective.
Robyn Williams: Why is it called Carrington, by the way?
Lucie Green: Ah, so Richard Carrington was a British son of a brewer who was also an amateur astronomer, and his passion was to study the Sun. And he was recording and drawing sunspots, which was the fashion in the 1800s, and he noticed a very, very bright light being given off by a sunspot group, the first time that had ever been seen. We now call that a solar flare. About 18 hours later the Earth's magnetic field completely went crazy.
Robyn Williams: And how did they notice that back then?
Lucie Green: It's a good question. At that point they did have magnetic measurements being made. So they were looking at how the Earth's magnetic field was changing. And so what they saw was a huge spike in these magnetic measurements. There was a spike at the time Carrington saw the flash of white light in the sunspot group, and then 18 hours later an even bigger spike as the eruption that was actually associated to this flash of white light finally reached the Earth. So Carrington gave us the first observation of something happening on the Sun, and then he was able to surmise that that event on the Sun caused these massive changes to the Earth's magnetic field.
Robyn Williams: Okay, well, 2013, not a terribly long way off, I hope you'll give us plenty of warning.
Lucie Green: I will be watching the Sun every second of every day and I will let you know what happens.
Robyn Williams: Glad to hear. Dr Lucie Green is a research fellow at the University College in London.
- Lucie Green
- Research Fellow
Mullard Space Science Laboratory
University College London
- Robyn Williams
- David Fisher