The dangers of solar storms
Sitting on Earth, going through the seasons every year, it can be easy to think the Sun is totally stable and unchanging; but it isn’t: periodically there are storms on the Sun, and if those storms fling material our way, it can cause us serious problems. Chris Smith spoke to Stephanie Yardley, from University College London, who studies these phenomena...
Stephanie - So basically they're huge bubbles of magnetic field and gas that the sun ejects, and they can travel at several million miles an hour through space, and sometimes they hit Earth. And when they reach Earth, in about one to three days on average, then they can interact with the Earth's magnetic field and also the atmosphere.
Chris - Isn't the sun slinging stuff at us all the time? That's called the solar wind, isn't it?
Stephanie - Yes. There's also the solar wind. There's also energetic particles as well. So we're constantly buffeted by the sun's wind.
Chris - But in terms of the intensity, you're saying one of these cosmic burps is far more powerful than just the normal wind that wafts our way off of the sun?
Stephanie - It depends on the conditions and that's why it makes it so difficult to predict, but generally the eruptions cause the spectacular displays of the Aurora. But that doesn't mean that we can't get effects from the solar wind as well or energetic particles.
Chris - Do we know why they happen and why the sun does this?
Stephanie - Yeah. So it's all to do with the magnetic field. So the sun has strong magnetic fields and if you imagine almost like an elastic band that twists and stretches, if you do that, then the elastic band will eventually break. And the same happens with the magnetic field. So it's essentially the sun storing energy in these magnetic fields and then it being released when they snap.
Chris - Do we therefore have a way of spotting when that elastic band is getting over tightened?
Stephanie - Yes. So we look at these regions on the sun of strong magnetic fields and essentially the way we predict what we call "space weather" - so just weather in space - is by looking at these regions and seeing when an eruption occurs. So we sit and stare at the sun and generally we look in wavelengths such as what we spoke about already, so ultraviolet radiation, and also visible light.
Chris - When this material arrives at Earth, what might it be able to do? We've talked about the health of our bodies being hit by sunlight and material from the sun such as UV radiation. But what about when these storms fling this debris our way, what impact does it have?
Stephanie - So as I've already mentioned, we have the spectacular displays of the Aurora, but you can also really affect our technology. Obviously we're very reliant on our technology nowadays and it can affect things like the power grids that we've already spoken about. So we can have power outages and the transformers can be severely damaged. They can affect things like the railway networks. Space flights - so astronauts on space walks, they can receive radiation, or even if you're on a passenger plane, if you're a passenger or crew on an airline aircraft, and also it can affect the actual electronics itself. So it can affect the aircraft itself or satellites and therefore affect communications and things like GPS.
Chris - How does it do that because this is just material coming from the sun, so how can it cause trains to go off kilter and electricity grids to melt down?
Stephanie - Well, it's all to do with the communication. So you can get things like signalling errors, for example, if the timings don't add up and that's all to do with communications going down. The power grids - you get currents induced in the ground from the changing of the magnetic field, of the Earth's magnetic field, so this can affect the power grids. And you can have power outages for hours but sometimes, if it's strong enough, then you can damage the transformers and they can take even several years to fix them.
Chris - So this has actually happened, it has a documented history of happening, and this is not just speculation - we've got this down, we know this happens?
Stephanie - Yeah. So one of the more recent events was in 1989, actually, where 6 million people went without power for nine hours in Quebec. And so this cost probably millions or billions of pounds. The biggest event we know of is called the Carrington event, quite a few people have heard of this, which was back in 1859. And we weren't so reliant on technology then so it only really affected the telegraphs and the telegraph operators were receiving shocks. But we had a near miss in 2012 - we call this the Near Miss Event, and it was during the Olympics. And so this eruption was actually not Earth directed, but if it was, maybe we might've lost the coverage of the Olympics. So who knows we're, you know, sitting and waiting for the next event to occur.
Chris - Perish the thought! So are we watching closely though? Do we have a way to do as good a forecasting for what the sun is doing as we can really forecast for weather on some parts of the surface now? Is there actually a physical program in place to do that?
Stephanie - Yeah. So we're sitting and staring at the sun and we're predicting all the time. Essentially what happens is an eruption will occur at the sun and we will then put this into models and model when it will arrive at Earth, but it's a bit harder than weather prediction so it's still quite difficult to do. And also, for example, the power grid or the national grid, they'll want five days of warning and we can't necessarily give them that lead time. So ideally scientists such as myself look at the regions that these eruptions come from to try and predict them before they happen, rather than once they've occurred. And even then things can go awry. And the eruption doesn't cause as much disruption as we thought, or it doesn't hit us head on, so obviously things evolve as they travel through space.
Chris - Is there anything we can do about this if you do detect an Earth bound storm coming our way?
Stephanie - So the main things, for example, for the power grids you can spread out the power, so you're less likely to get damaged. Or for example, if you're in an aircraft, you can fly at lower altitudes or I guess in a really extreme case you can ground the flights, but obviously doing stuff like this costs money. So we have to be sure that these events are going to happen and are going to affect us.