Double Solar Storms Headed to Earth

A rare double burst of magnetically charged solar storms will hit Earth Thursday night and Friday, raising concerns that GPS signals, radio communications and power transmissions could be disrupted, officials said on Thursday.

Individually, the storms, known as coronal mass ejections, or CMEs, wouldn't warrant special warnings, but their unusual close timing and direct path toward Earth spurred the National Oceanic and Atmospheric Administration's Space Weather Prediction Center to issue an alert.

The first CME, which burst from a magnetically disturbed region of the sun on Monday night, should reach Earth Thursday night, center director Thomas Berger told reporters on a conference call.

The same patch of solar real estate produced a second, more powerful storm about 1:45 p.m. EDT/1745 GMT on Wednesday. "We don't expect any unmanageable impacts to national infrastructure from these solar events at this time, but we are watching these events closely," Berger said.

The sun currently is in the peak of its 11-year cycle, though the overall level of activity is far lower than a typical solar max.

Storms as powerful as the ones now making their way toward Earth typically occur 100 to 200 times during a solar cycle, Berger said.

"The unique thing about this event is that we've had two in close succession and the CMEs could possibly be interacting on their way to Earth, at the Earth's orbit or beyond. We just don't know that yet," he said.

The highly energetic, magnetically charged solar particles could hit Earth's magnetic field and disrupt some radio communications and degrade GPS signals, NOAA said.

The storms also have the potential to impact electric field power grids in the northern latitudes, which are more susceptible to geomagnetic disturbances.

Power grid operators and the Federal Emergency Management Agency (FEMA) have been notified "just in case," Berger added.

On the plus side, the storms should trigger beautiful auroral displays, visible wherever clear skies prevail along the northern tier of the United States. Aurora are caused by electrically charged solar particles hitting oxygen, nitrogen and other gases high in the atmosphere, creating curtains of light above the planet's magnetic north and south poles.

(Editing by Eric Walsh)