The violent solar storms that threaten the Earth

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Scientists have been warning that a violent solar storm could disrupt communications on Earth and cause massive economic damage. Why are solar storms such a threat?

In 1972, dozens of sea mines off the coast of Vietnam mysteriously exploded — and it has recently been confirmed that the explosions were caused by solar storms, which can significantly destabilize the Earth’s magnetic field.

Today, the effects of such an event could be much more serious, crippling the technology we use for everything from satellites to electricity grids. The cost to the economy of such an unexpected event in the UK alone has been estimated at £16 billion.

There are good reasons for our vulnerability to events happening millions of miles from Earth.

What causes an extreme solar event?

The Sun is a star — a mass of boiling hydrogen charged with electricity. As this fluid moves, it accumulates energy in its complex magnetic field.

This magnetic energy is released by intense rays of light known as solar flares and by vast emissions of material and magnetic fields known as coronal mass ejections or solar storms.

While eruptions can disrupt radio communications on Earth, solar storms pose the greatest threat. Each storm contains energy equivalent to 100,000 times the world’s entire nuclear arsenal, but that energy is spread across a huge volume of space.

The Sun spins around like an immense set of spinning fireworks, spewing emissions in all directions into space. If one of these eruptions is launched towards our planet and its magnetic field is in opposite alignment with Earth’s, the two fields can come together. As the solar storm sweeps through space, part of Earth’s magnetic field is distorted into a long tail.

And the moment this distorted magnetic field aligns itself again, it accelerates electrified particles towards Earth. Here, they reach the upper atmosphere and heat it up, glowing spectacularly and forming what is known as the aurora australis and borealis.

But this distortion of Earth’s magnetic field has other, more significant effects. It is believed to have triggered the sea mines off the coast of Vietnam in 1972. The mines had been designed to detect small variations in the magnetic field caused by approaching ships with metallic hulls. But its engineers did not imagine that solar activity could have the same effect.

When will the next extreme solar event occur?

Scientists are looking for clues about what causes these vast eruptions and, after they’ve been launched by the Sun, how to track them through interplanetary space.

Our records of Earth’s magnetic field date back to the mid-19th century. They suggest the probability of an extreme space weather event occurring every 100 years, but smaller events occur more frequently.

In 1859, the Carrington Event — the largest solar storm ever recorded — caused sparks in telegraph systems and the aurora borealis was even observed in the Bahamas.

The next time it happens, its effects are likely to be much more serious.

With each cycle of solar activity, our global community becomes more dependent on technology. Today, space satellites are critical for global communication and navigation, while aircraft connect continents and extensive electrical grids crisscross the planet. All of them could be seriously affected as a result of extreme solar events.

The electronic systems of planes and spacecraft could be damaged, as accelerated energy particles in our atmosphere can destroy their miniaturized electronic circuits. On the other hand, power grids on land can be overloaded by excess electrical current.

How can we plan

Several satellites and electrical grids have failed during recent space events, making it clear that the Sun needs to be carefully monitored to help predict when a solar storm will affect Earth.

Forecast experts are working on it all over the world, from the Meteorological Offices in the UK and Australia to the Noaa Space Weather Prediction Center in the United States. If all goes well, they can detect when a storm is heading towards Earth and predict its arrival time six hours in advance.

This forecast still offers relatively little lead time, but could reduce costs to the UK economy, for example, from £16bn to £3bn (from £122.5bn to £23bn).

Space weather is now included in the UK government’s risk register, alongside other more well-known risks such as flu pandemics and severe flooding. Space weather is considered a risk equivalent to a severe heat wave or the emergence of a new infectious disease.

Government agencies are now communicating with energy companies, spacecraft operators and airlines to ensure they have plans in place to limit the impact of extreme space weather events. It is critical, for example, to ensure that there is enough energy to cool stocks of food and medicine, as well as ensuring that water and fuel can be pumped as needed.

If communication with some satellites is lost, technologies known as navigation satellites and satellite television may stop working. Spacecraft engineers study extreme events to be able to provide resistance to space vehicles, protecting vulnerable electronic circuits and installing backup systems.

Accurate space weather forecasts will allow operators to better protect their equipment, ensuring its safety after the storm passes.

Many planes fly over the North Pole on their travels between Europe and North America. During space events, aircraft operators divert their planes away from the polar skies, where most energy particles enter Earth’s atmosphere. This bypass allows limiting exposure to high doses of radiation and ensuring reliable radio communication.

We’ve learned a lot about space weather since the events of 1972, but as modern technologies evolve, we need to ensure they can withstand even the worst conditions the Sun can offer us.

* Chris Scott is professor of atmospheric and space physics at the University of Reading, UK.

This analysis was commissioned by the BBC from an expert working for an outside organization and edited by Eleanor Lawrie.

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