History paints a stormy future

The last solar cycle officially peaked in July 1989, as measured by the number of monthly sunspots. But a second, only slightly less active peak came four months later. And the worst space storms from that cycle came after the main peak -- in November 1989, and even into July 1991.

Will we stay on a plateau for two years, like the last cycle, or has a slow decline already begun?

"No good answer," Murtagh said. "We certainly do expect several active periods in the next two years."

While this solar maximum has not been an historical whopper, it's no slouch. Two radiation storms this year were the third and fourth most severe since 1975. And a geomagnetic storm on July 15 was the worst since 1991. Geomagnetic storms arrive later than radiation storms, last longer and fuel the colorful lights known as auroras.

But major problems have not come, as they did in 1989 when a solar storm triggered a power surge that damaged a transformer at Hydro-Quebec, leaving 6 million people in Canada and the northeastern United States without power for more than nine hours. The current cycle has caused no more than some relatively minor radio blackouts and a few small satellite problems.

Satellites: Weathering the storms

Engineers design satellites to handle space weather. They know that heavy doses of radiation can fry an expensive electronic camera or disable navigational equipment.

But space can be a tricky place, and there's a lot going on up there that is still a mystery. Just ask the scientists who operate the XMM-Newton.

Twice on each orbit, both XMM and Chandra cross Earth's radiation belts, which extend out from the planet some 25,000 miles (40,000 kilometers). In this danger zone, charged particles -- essentially protons and electrons -- are trapped by Earth's magnetic field. Engineers planned for this, and forecasters can predict the arrival of major space storms that heighten the danger. Sensitive instruments on the spacecraft are shut down.

But more minor and mysterious waves of radiation, not confined the radiation belts, have buffeted the craft without warning -- and so far have stumped researchers.

In one gust, a sheet or cloud of protons, estimated to be 6 miles (10 kilometers) thick, pounded the telescope with 300 impacts per square centimeter (0.16 square inch) every second for fifteen seconds. The mysterious brief gusts are made of protons that pack less of a punch than larger, more predictable bouts of space weather.

"It is like trying to predict a gust of wind in a specific place at a specific time," said Fabio Giannini of the European Space Agency (ESA). "It appears that the Earth's magnetic field can concentrate these low-energy particles."

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