A major storm just passed through, but you might not have noticed because it happened out in space. The sun is at its 11-year peak of activity, and its solar disturbances are sending a lot of "space weather" in our direction.
While these "weather" patterns might pass us by far overhead, the storms can still affect us indirectly by knocking out electricity power grids, putting mobile phones on the blink and blacking out satellites. The world loses a satellite once every two years on average because of this solar activity, and lost satellites can mean lost technological services.
Space weather came under discussion at the weekend at the American Association meeting in Washington DC. The director of the space environment centre at the US National Oceanic and Atmospheric Administration, Dr Ernest Hildner, described the different types of storms, their effects and a new five-level scale used to measure their severity, ranging from "minor" to "extreme".
The storm that reached the Earth this past weekend was a G3, a "strong" storm powerful enough to cause some disturbance to power systems and require extra vigilance from satellite operators.
The "G" stands for "geomagnetic", one of three storm types which include solar radiation storms and radio blackout storms. Most storms pass unnoticed, as did this weekend's, but the effects of a bad storm are not trivial, explained Dr John Kappenman of Metatech Corporation, which specialises in protecting power grids.
A strong geomagnetic storm a few years ago plunged six million people in Quebec into darkness, with the storm collapsing a large power network in just 90 seconds.
It is important for airline flight crews and astronauts to know about these storms, said Dr Mark Weyland of Lockheed Martin, who spoke about efforts to reduce the radiation exposure to crews. Radiation levels climb rapidly during a solar event, he said. "Our primary concern for crews is cancer induction."
A level 4 solar radiation storm could cause radiation doses equivalent to receiving 10 chest X-rays for airline crews flying in the northern latitudes, Dr Kappenman said.
The storms are the result of magnetic disturbances on the solar surface, with highs and lows occurring on a regular cycle. A peak in activity drops away to a valley and returns to a peak over 11 years, with peaks recognised by intensive sunspot activity.
A "solar maximum", as it is called, will take place this year, Dr Hildner explained. Our ability to predict storms is relatively poor, however, he said, and so we generally have little warning. Events on the sun can be seen, but we often don't know what type of storm or its severity until it arrives.
