Solar burps

7 03 2012

So sorry for not posting more – life has been utterly hectic over the past few months.

Is the solar storm headed our way something to worry about? Should we hunker down inside and disconnect our TVs, toasters and breadmakers? Or is this just hype about a non-event?

The truth, as always, is somewhere in between. Solar storms can cause very real problems for electrical equipment. Residents of Quebec still remember the power outage in March 1989, that left many regions in the province without power for 9 hours. Five years later two of the Anik communication satellites were taken out of commission, one for hours, another for months, due to a solar storms.

But why exactly does electrical equipment take such a bashing in these storms while we seem just fine? And for that matter, what are these storms actually anyway???

Let’s deal with the second question first. Despite the Sun’s warm glow looking constant from day to day, in fact its surface is highly active. The truly incredible amount of power released every second in the Sun, roughly 25 trillion (i.e. 25,000,000,000,000!) times that required by the inhabitants of the Earth, makes its surface bubble like a cauldron. We can see structure on scales from thousands of kilometers down to just a few (see this incredible image for an example) and probably smaller.

Sun spots are just a very visible part of all this activity. They’re caused by regions of intense magnetic field activity and have enormous amounts of stored energy within them. All this energy can produce huge flares/eruptions which send billions of tons of hot plasma into space travelling at two million kilometers per hour.

And the Earth is often right in the firing line.

But it isn’t as bad as it sounds. While billions of tons travelling at high speed sounds like it would wipe out everything in its path, by the time it reaches the Earth it’s spread out over a vast area. The density is so low by the time it reaches us that if you could imagine standing up in the “wind” of particle travelling at millions of kilometers an hour, you wouldn’t feel a thing. But your body’s cells would. Constant bombardment of DNA with these high energy particles leads to cancer. That’s one of the reasons why sending astronauts to Mars is so tough. How do we protect them?

But the good news is while we’re on the surface of the Earth, our magnetic field protects us from the worst of these high energy particles, diverting them away and concentrating them around the poles – that’s what produces the aurora. But this safety net comes with a price. Under this flood of electrically charged particles our magnetic field changes and distorts, some times incredibly rapidly.

Why is that a problem?

Well, over 180 years ago Michael Faraday showed that if you change the magnetic field over a wire, it will produce an electric current. It’s a really simple idea that has incredibly profound consequences. Electric motors run on this principle.

But now take the magnetic field around the Earth and change it. Where are the wires? All around us! The power grid is the biggest example. When magnetic fields change on scales tens and hundreds of kilometers across, then you can really start getting some serious electrical currents induced. In 1989, it was enough to shut down the Quebec power grid.

These are all serious events. Lost satellites can cost billions of dollars. Losing a power grid can be equally costly, not to mention public safety issues. So it should come as no surprise that predicting these events, and building in safety measures for both satellites and power distribution systems is taken very, very seriously. Early warning systems are well in place now – we get anywhere between two and five days notice.

But the truth is we haven’t really seen a truly huge solar storm in over 100 years. Neither of these two events in 1989 & 1994 compares to the great solar storm of 1859. That flare produced currents so large that telegraph equipment produced huge sparks within offices and aurora were seen almost all around the globe. Compared to the so called “Carrington event” of 1859, what we’re seeing now are small solar “burps”.  Yet even the 1859 event is dwarfed by what we see on other stars. One distant event seen with an X-ray telescope corresponded to a flare so powerful (100,000x a typical solar flare) it would have caused mass extinction on the Earth if it came from the Sun. But don’t worry, the Sun isn’t about to do anything quite that bad.

It makes you think. The Sun may give us life, but one extra big belch from it could produce some real problems.

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