The Biggest Solar Storm in History

It was the 2 September 1859. The clipper ship Southern Cross was off Chile when, at 1:30am, itsailed into a living hell. Hailstones from above and waves from all around whipped the deck. When the wind-lashed ocean spray fell away to leeward, the men noticed they were sailing in an ocean of blood. The colour was reflected from the sky, which, they could see - even through the clouds - was wreathed in an all-encompassing red glow.

The sailors recognised the lights as the southern aurora that usually graced the skies near the Antarctic Circle, just as their northern counterparts cling to the Arctic. To see them from this far north was highly unusual. As the gale subsided, they witnessed an even more astonishing display. Fiery lights loomed against the horizon as if some terrible conflagration had engulfed the Earth. Vivid bolts flew across the now clear sky in spiral streaks and exploded in silent brilliance, as if the very souls of all humanity were fleeing whatever cataclysm had befallen the planet.

Upon their arrival at San Francisco, the ship's company discovered that theirs was not an isolated experience. Two thirds of the Earth's skies had been similarly smothered. Also, there was a sinister side to the aurorae.

The beguiling lights had disabled the telegraph system, wiping out communications across the world. For days, nature refused to allow these arteries of information to flow freely. It was as if today's Internet had suddenly, inexplicably shut down. Worse still, the aurora also threatened life and limb.

In Philadelphia, a telegrapher was stunned by a severe shock. In some offices the equipment burst into flames. In Bergen, Norway, the operators had to scramble to disconnect the apparatus, risking electrocution. On top of this, compasses spun uselessly under the grip of the aurora, disrupting global navigation.

In the scramble to understand just what had engulfed Earth, the Victorians had only one clue.On the previous morning amateur astronomer Richard Carrington was working in his private observatory at Redhill, Surrey, (left) and found himself witness to an unprecedented celestial event.

He was studying sunspots, the unexplained dark blemishes that occasionally speckle the Sun. The sunspot that Carrington gazed upon that day was huge, almost ten times the diameter of the Earth. Yet on the Sun, it barely stretched a tenth of the way across the fiery disc. Without warning, two beads of searing white light appeared over it.

No one had ever described the Sun behaving like this before and Carrington instantly began timing the lights as they drifted across the sunspot, faded and vanished. That night, the apocalyptic aurora burst over the Earth. Could it be that Carrington's titanic explosion had somehow hurled the electrical and magnetic energy at the Earth? If so, how?

Carrington himself never pursued the research. He became embroiled in a sex and drugs scandal that destroyed his reputation and then ended his life. Yet his discovery of the solar flare began half a century of intrigue, rivalry and speculation as other astronomers raced to understand the mysterious way in which the Sun could reach out across 93 million miles of void and strike the Earth. With the benefit of hindsight, we can see that the Carrington flare was a tipping point for astronomy. Suddenly aware that the Earth and its technology could be affected by celestial events, astronomers turned their attention away from charting the positions of stars to aid navigation, and began studying the nature of the celestial objects.

Today, the study continues. Astronomers routinely watch solar flares with their spacecraft and know that these explosions usually eject huge clouds of electrically-charged particles into space. When these strike the Earth, they produce the aurora in the atmosphere and cause technology to malfunction. Astronomers call it space weather and the ferocity of it still occasionally catches them unawares. In October 2003, a Japanese weather satellite died during a solar storm. In 1989, millions of North Americans were blacked out when a solar storm damaged the Hydro-Quebec power station in Canada.

In all these studies, however, there is one sobering thought. The scale of the solar storm of 1859 has never been equalled since. Even the fiercest recent storms are between three and five times smaller. With our current reliance on technology higher than at any time in history, another "Carrington-event" could cost us billions.