1 September 1859: the ‘Carrington Event’, the biggest solar storm ever recorded

The morning of 1 September 1859 was lovely and sunny in the south of England. That was good news for amateur astronomer Richard Carrington, who had a particular fondness for observing the sun. That day, he went up to his private observatory, pointed his telescope at the sun, and began to sketch the sunspots. What he saw next got him very excited indeed.

"Two patches of intensely bright and white light broke out" of the sun, wrote Carrington, and hurled invisible particles towards the earth. It didn't take long for the particles to smash into our magnetic field and light up the skies. That night, bright red and green auroras could be seen as far south as Cuba.

The “Carrington Event”, as it came to be called, was the biggest solar storm ever witnessed. It created huge electrical surges that sent sparks flying from new-fangled telegraph machines, in some cases setting the telegraph paper on fire. Operators disconnected their machines from their batteries, but found they could still communicate via the “power of the aurora”.

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We got a taste of how the world would cope now if such an event happened again (as it will – research suggests such a storm could occur as often as every 150 years) when in October 1989 a geomagnetic storm blew out the power grid in Quebec, plunging six million people into darkness.

In the US, between 20 million and 40 million people would be at risk of power cuts that could last from a couple of weeks to a couple of years. The costs to the US economy, estimated in 2013 by Lloyds of London, would be between $0.6trn and $2.6trn. Damage to the 900-odd satellites orbiting earth could cost between $30bn and $70bn.

Thankfully, the power grid in the UK is more resilient than in many parts of the world, according to the UK's Space Weather Preparedness Strategy. But we could still face “two to four months of disruption to power supplies”.