With no warning, the lights go out. A sudden loss of electrical power has struck the whole country. Air traffic control goes offline, hospitals switch to back-up generators and as you wait it out at home a stunning aurora dances in the sky above your head.


The blackout stretches on. Hours become days and the power does not return. There is no internet, TV or newspapers to tell you what is happening. Soon, the diesel driving the hospitals’ emergency generators runs out and food stops arriving in supermarkets because fuel for the delivery trucks can’t be pumped without electricity.

Why is nothing working? An extraordinarily powerful solar storm has battered the Earth causing phantom currents in the power lines and damaging the transformers beyond repair. But that’s not all it has destroyed. High above us, many of the satellites that we rely upon for communications and navigation have been reduced to useless junk.

In short, the technological trappings of our civilisation have been wrecked by a hail of electrified, superheated gases, catapulted from the Sun with the energy of a thousand atomic bombs.

It is the natural disaster to top them all. And the greater our reliance on technology, the more vulnerable we are; thus it’s the developed world that would suffer most from this particular threat. Should an extreme solar flare hit us, it will take up to a decade to fully recover. It may take months just to reconnect the country’s essential infrastructure with electricity.

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Sound far-fetched? Not according to a report by the National Academy of Sciences (NAS), published in the US back in January. Daniel Baker is the chairman of the board that produced the report to investigate the impact of an extreme solar event. “What would it be like without power on a continental scale for months? It is almost inconceivable,” he says.

We got a hint of what it might be like in 1989, when north-eastern Canada’s power grid was knocked out during a solar storm. In just 90 seconds, the region went from operating normally to suddenly having six million people without electricity. It took nine hours to re-route electricity into that part of the power grid. Repairs took months. But that was by no means a big solar flare. In the aftermath of an extreme solar storm, the problems would be on a much greater scale.

Forecasting a storm

Solar storms are largely unpredictable right now. They occur when magnetic fields near the Sun’s surface change their configuration, giving out energy that catapults particles from the solar atmosphere into space. If this solar flare is aimed at Earth, it takes between 18 and 36 hours for an eruption to reach us. And when it hits our atmosphere, it causes a solar storm. The only warning we get is from NASA’s Advanced Composition Explorer (ACE) satellite. The ACE can provide between 15 and 60 minutes of warning of an incoming solar storm, but that is not enough time to do very much about it.

So, solar physicists are hard at work trying to understand what triggers solar flares in order to improve their ability to forecast them. At the forefront of this research is a brace of NASA spacecraft called STEREO (Solar Terrestrial Relations Observatory). “We are looking to find signatures that will show when a flare is about to happen,” says Chris Davis at the Rutherford Appleton Laboratory in Didcot, who works on a team that tracks these massive eruptions as they speed towards Earth.

STEREO consists of one spacecraft millions of kilometres ahead of Earth and another the same distance behind, both on the same solar orbit as Earth. They look into the region of space between the Sun and the Earth, with some instruments trained on the Sun itself.

One promising signature appears to be the sudden appearance of an expanding bubble of plasma just above the Sun’s surface. This seems to pinpoint the location of where a solar flare is about to explode, giving a day or two’s notice of the explosive event.

Once the flare has fired, Davis’s team can begin an analysis of any eruption of solar gas. Being able to look from two different vantage points, the scientists can reconstruct the eruption in 3D. “We can determine the direction of an eruption, which helps with forecasting whether it will hit Earth,” says Davis.

Once a disturbance hits Earth’s atmosphere there are other physicists watching. James Borderick, at the University of Leicester, uses the Super Dual Auroral Radar Network (SuperDarn) to watch particles entering the atmosphere at both the North and South Poles to understand how solar storms interact with the planet and cause their devastating effects. “We are in the best position we have ever been to observe and study space weather,” he says. “The number of ground- and space-based facilities are better than ever.”

But what happens when the scientists see an extreme solar event blasting towards us? The answer is sobering. “There isn’t a safe place,” says Mike Hapgood, chair of ESA’s Space Weather Working Team. In most disaster situations, aid can flow into the affected region from outside. With a solar storm, it strikes such large areas that there may be no ‘outside’. Everywhere that relies on electrical power is potentially affected.

The big one

The last gigantic solar storm took place in 1859, exactly 150 years ago this month. Known as the Carrington event (amateur astronomer Richard Carrington observed the solar flare that triggered it), this superstorm still tops the scale of solar events that have affected the Earth. Back then, the communications technology was the telegraph network, while compasses and canny seamanship handled global navigation. As the storm hit, compasses spun uselessly, and the telegraph network went down, swamped with electrical currents produced by the aurorae high above.

Today, the satellites that enable global navigation and communication are all situated in highly vulnerable positions above the Earth. In 2003, a series of solar storms battered the planet around the Halloween period. At least two satellites were rendered useless and almost 60 per cent of NASA satellites malfunctioned in some way. Airliners were diverted to avoid potentially high radiation doses to the passengers and radio blackouts with air traffic control.

A Carrington-sized event would be far worse. January’s NAS report estimates that another solar superstorm could cause $1-2 trillion dollars of damage to the US economy alone. So what can we do?

“The only real protection is to switch everything off,” says Hapgood. This solution, however, comes at a high price. “If you do that, people will die. There will be accidents because of the power outage, and what if the back-up generators do not work?” But perhaps it is better to suffer a few hours of dangerous blackout than risk months without power?

It’s anyone’s guess when the Earth might be struck by another superstorm. Solar activity waxes and wanes in an 11-year cycle. We are currently in a period of low activity, known as solar minimum, waiting for the next cycle to begin and ramp up to a maximum around 2012 or 2013. All the indications are that the coming cycle is going to be the least active for 80 years. But this will not protect us from giant flares, because the Carrington event took place when the Sun was similarly inactive.

So we wait while scientists try to persuade governments to take the threat seriously, and try to understand more about these extreme events. Following the NAS report, Baker is now discussing the best way to prepare for such an event with the US Government. “The challenge is not to be alarmist, not to overstate the case, but not to underplay it,” he says.


So you may want to buy a few more tins of baked beans, and some candles – just in case.


Dr Stuart Clark is an astronomer, science journalist and author of several popular science books, the latest of which is Beneath the night: How the stars have shaped the history of humankind. You can find a version of his book, remade for radio, called Beneath the Night over on BBC sounds. Stuart is also a fellow of the Royal Astronomical Society and he regularly works with European Space Agency to communicate their work to the general public.