'Pushed back to the Stone Age': massive solar storm missed Earth by just one week

The burst of radiation would have been strong enough to destroy equipment such as navigation satellites and communications and trigger widespread blackouts had it hit the Earth, according to NASA.

“We would have been well and truly pushed back to the Stone Age for days,” said Alan Duffy, an astrophysicist at Swinburne University, of the most powerful solar storm detected in more than 150 years.

Daniel Baker of the University of Colorado told NASA’s Science News blog that the Earth and its inhabitants were “incredibly fortunate” the eruption happened when it did.

"If the eruption had occurred only one week earlier, Earth would have been in the line of fire,” Dr Baker said. "If it had hit, we would still be picking up the pieces."

A previous extreme solar storm - known as the Carrington Event of September 1859 after the English astronomer Richard Carrington – caused telegraph poles to ignite but only minimal damage to Victorian societies just beginning to industrialise.

Northern lights, sparked by geomagnetic storms, were seen as far from the poles as Cuba and Tahiti, NASA said.

The July 23, 2012 event, though, would have triggered a “catastrophic effect on modern power grids and telecommunications networks,” the US space agency said. It cited a National Academy of Sciences study that estimated the impact would have been 20 times that of Hurricane Katrina, which devastated New Orleans in 2005, or some $2 trillion dollars.

The bursts came during a relatively inactive period of solar magnetic activity. This month, for instance, has been a period with remarkably few sun spots, a phenomenon scientists are still trying to understand.

'12 per cent chance'

While the 2012 storm – known as a coronal mass ejection (CME), with its billion-tonne clouds of magnetised plasma – was observed by astronomers at the time, the nature of the event and its possible impact have only reached a wider audience with the publication of scientific papers.

The chances of a solar storm with the intensity of the Carrington Event – which was more powerful that the 2012 one – hitting the Earth in the next 10 years is about 12 per cent, or one in eight, according to a paper cited by NASA by Pete Riley and published in Space Weather.

Modern societies are highly exposed to the effects of solar storms even of much lower intensity.

“We have literally ringed our planet with electric wires,” Dr Duffy said.

Although aircraft are strengthened against magnetic bursts, such as from lightning, pilots would likely have lost satellite navigational aids if the 2012 solar storm had hit the Earth. Airports would probably have lost power and communications, making landing hazardous.

“There’d be panic in the air,” Dr Duffy said.

The storm now appears to have involved two CMEs, about 10 to 15 minutes apart, according to University of California Berkeley space physicist Janet Luhmann and Ying Liu, writing in Nature Communications. Importantly, the storm passed through a region of space that had been “cleared out” by a separate CME only four days earlier, NASA said.

“As a result, the storm clouds were not decelerated as much as usual by their transit through the interplanetary medium,” NASA said.

Satellite companies will be among those watching the research with interest, given the vulnerability of their equipment to bursts of solar magnetism, Swinburne’s Dr Duffy said. Early warning of a CME, particularly if it follows the path on a previous eruption, could give them time to shut down their equipment and limit damage.

For ordinary punters, “there’s nothing you can do short of unplugging your equipment” – such as computers – if you get the warning in time, Dr Duffy said.

The most resilient part of society would probably be the military, elements of which in some nations are hardened against the effects of a nuclear war. Nuclear weapons send a similar electro-magnetic burst that can fry electronics, he said.