Raging sun provides earthly light show.

At the tumultuous peak of its 11-year activity cycle, the sun is spitting out X-ray flares and belching giant clouds of high-energy particles at a furious rate. On April 2, the sun unleashed the most powerful flare recorded since regular measurements began 25 years ago.

Packing more energy than 100 megatons of TNT, the flare erupted from a turbulent region on the sun's northwest edge that had grown to be 13 times bigger than Earth's surface. Because the explosive region soon rotated onto the sun's far side, Earth was spared the brunt of the storm. Nonetheless, ultraviolet and X-ray radiation from the flare triggered a temporary radio blackout on Earth's sunlit side.

The flare was more powerful than the infamous one that disrupted power grids in Canada on March 6, 1989, during the peak of the last solar cycle, notes Paal Brekke, a European Space Agency scientist based at NASAs Goddard Space Flight Center in Greenbelt, Md.

With solar activity expected to continue at a peak level for another year, the sun's rage is far from over. Over the past few weeks, coronal mass ejections--huge clouds of electrified gas hurled from the sun's outer atmosphere--have created giant shock waves that plowed into Earth's magnetosphere, our planet's magnetic cocoon. These waves generated powerful geomagnetic storms. As a result, charged particles that normally crash into Earth's polar regions creating the shimmering lights known as auroras moved to lower latitudes.

Sky watchers observed dazzling displays of these so-called northern lights as far south as Mexico. "It was a wide or broad veil of a silvery yet delicately faint glow in the northern sky," says Chris Grohusko of El Paso, Texas, describing the aurora borealis he photographed in southern New Mexico on April 11.