Ice cores suggest that such a blast of solar particles happens only once every 500 years, but even the storms every 50 years could fry satellites, jam radios and cause coast-to-coast blackouts.

The cost of such an event justifies more systematic solar monitoring and beefier protection for satellites and the power grid.

The impact of the 1859 storm was muted only by the infancy of our technological civilization at that time. Were it to happen today, it could severely damage satellites, disable radio communications and cause continent-wide electrical blackouts that would require weeks or longer to recover from. Although a storm of that magnitude is a comfortably rare once-in-500-years event, those with half its intensity hit every 50 years or so. The last one, which occurred on November 13, 1960, led to worldwide geomagnetic disturbances and radio outages. If we make no preparations, by some calculations the direct and indirect costs of another superstorm could equal that of a major hurricane or earthquake .

 Source : Scientific American

As night was falling across the Americas on Sunday, August 28, 1859, the phantom shapes of the auroras could already be seen overhead. From Maine to the tip of Florida, vivid curtains of light took the skies. Startled Cubans saw the auroras directly overhead; ships’ logs near the equator described crimson lights reaching halfway to the zenith. Many people thought their cities had caught fire. Scientific instruments around the world, patiently recording minute changes in Earth’s magnetism, suddenly shot off scale, and spurious electric currents surged into the world’s telegraph systems. In Baltimore telegraph operators labored from 8 p.m. until 10 a.m. the next day to transmit a mere 400-word press report.

Just before noon the following Thursday, September 1, English astronomer Richard C. Carrington was sketching a curious group of sunspots—curious on account of the dark areas’ enormous size. At 11:18 a.m. he witnessed an intense white light flash from two locations within the sunspot group. He called out in vain to anyone in the observatory to come see the brief five-minute spectacle, but solitary astronomers seldom have an audience to share their excitement. Seventeen hours later in the Americas a second wave of auroras turned night to day as far south as Panama. People could read the newspaper by their crimson and green light. Gold miners in the Rocky Mountains woke up and ate breakfast at 1 a.m., thinking the sun had risen on a cloudy day. Telegraph systems became unusable across Europe and North America.

The news media of the day looked for researchers able to explain the phenomena, but at the time scientists scarcely understood auroral displays at all. Were they meteoritic matter from space, reflected light from polar icebergs or a high-altitude version of lightning? It was the Great Aurora of 1859 itself that ushered in a new paradigm. The October 15 issue of Scientific American noted that ‘‘a connection between the northern lights and forces of electricity and magnetism is now fully established.” Work since then has established that auroral displays ultimately originate in violent events on the sun, which fire off huge clouds of plasma and momentarily disrupt our planet’s magnetic field.

The impact of the 1859 storm was muted only by the infancy of our technological civilization at that time. Were it to happen today, it could severely damage satellites, disable radio communications and cause continent-wide electrical blackouts that would require weeks or longer to recover from. Although a storm of that magnitude is a comfortably rare once-in-500-years event, those with half its intensity hit every 50 years or so. The last one, which occurred on November 13, 1960, led to worldwide geomagnetic disturbances and radio outages. If we make no preparations, by some calculations the direct and indirect costs of another superstorm could equal that of a major hurricane or earthquake.

The Big One
The number of sunspots, along with other signs of solar magnetic activity, waxes and wanes on an 11-year cycle. The current cycle began this past January; over the coming half a decade, solar activity will ramp up from its current lull. During the previous 11 years, 21,000 flares and 13,000 clouds of ionized gas, or plasma, exploded from the sun’s surface. These phenomena, collectively termed solar storms, arise from the relentless churning of solar gases. In some ways, they are scaled-up versions of terrestrial storms, with the important difference that magnetic fields lace the solar gases that sculpt and energize them. Flares are analogous to lightning storms; they are bursts of energetic particles and intense x-rays resulting from changes in the magnetic field on a relatively small scale by the sun’s standards, spanning thousands of kilometers. So-called coronal mass ejections (CMEs) are analogous to hurricanes; they are giant magnetic bubbles, millions of kilometers across, that hurl billion-ton plasma clouds into space at several million kilometers per hour.

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