When the sun brought darkness

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When a huge solar flare Thursday sent a magnetic storm heading toward Earth, Americans heard the usual warnings of possible power outages, disruption of satellite communications and other effects -- and for the most part ignored them.

The warnings seem to come with every such event. "Heard it all before." "They always say that." Familiarity breeds contempt.

And yet Canadians in Quebec province probably felt the same way on March 13, 1989, complacent and happily going about their business -- until the lights went out in the early-morning hours, the start of a 12-hour blackout that left people stranded in dark office buildings by stalled elevators, or waking up to up to cold homes.

Schools and businesses were closed by the blackout, and the Montreal Metro commuter system was shut down during the morning rush hour.

The entire province of Quebec had suffered a loss of electricity.

The cause? A solar storm.

Six days earlier, astronomers had witnessed a powerful solar flare, resulting three days later in a so-called coronal mass ejection, a burst of matter and electromagnetic radiation into space.

This solar storm of electrically charged particles, when it reached the Earth, began creating extremely intense auroras at the Earth's poles, with some in the Northern Hemisphere visible as far south as Texas.

Satellites in polar orbits did not respond to signals from the ground and tumbled out of control for several hours, and weather satellites stopped sending images to Earth.

The intense magnetic disturbance actually created electrical currents in the ground beneath much of North America, and at 2:44 a.m. on March 13, those currents found a weakness in the electrical power grid of Quebec, tripping circuit breakers on Hydro-Quebec's system.

The entire grid went down in less than 2 minutes.

In a cascade effect, U.S. utility companies found themselves dealing with problems of their own. Across the United States more than 200 power grid problems erupted within minutes of the start of the outage, although fortunately none caused a blackout.

Quebec was particularly vulnerable because it sits on a large geological shield of igneous rock.

Such areas are the most vulnerable to the effects of intense geomagnetic activity because the high resistance of the igneous rock prevents current from the storms flowing through the Earth, and in the Quebec blackout it found a less-resistant path by traveling through Hydro-Quebec's long-distance transmission lines, eventually overloading them and tripping the system's breakers.

In the wake of the outage, Hydro-Quebec implemented various strategies to prevent such events in the future, including raising the breaker trip level, installing protections on ultra high voltage lines and upgrading various monitoring and operational procedures.

Other utilities took note, and in North America, Northern Europe and elsewhere they implemented programs to reduce the risks associated with geomagnetically induced currents.

Could such a thing happen again?

Scientists say solar storms of the magnitude of the 1989 event are rare, and it would require an enormous flare and coronal mass ejection to create conditions that would trigger a Quebec-style blackout.

Still, the sun, for all we've learned about it, remains something less than predictable in its behavior.

Which is why they issue those warnings about which perhaps we shouldn't be quite so complacent.