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 NASA’s 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.
