Solar Blasts Slam Into Earth

By CASSANDRA SWEET

Two blasts of energy from the sun hit the Earth's magnetic field Friday and could disrupt one or more electrical grids, global-positioning systems or other satellite-communications systems, scientists at the National Oceanic and Atmospheric Administration said Friday.

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National Oceanic and Atmospheric Administration

X-ray image of the sun, taken by spacecraft on Aug. 4.

The blasts touched Earth's magnetic field in the form of fast-moving "solar wind" and is blowing by the Earth, Joseph Kunches, a space weather scientist with NOAA's Space Weather Prediction Center, said in an interview.

Mr. Kunches said it is too early to know what the effects of the blasts will be. "If it's a really big storm, it still could be active [Saturday] night, but this kind of disturbance level won't be sustained for long," he said.

But Mr. Kunches added, "It seems that the magnetic field is getting hit harder than we thought it would."

The storms are two of three large explosions from the sun's surface since Tuesday, according to NOAA.

The agency has notified U.S. electric-grid and satellite-communication operators of the events, which could interfere with some communications, particularly those that are closest to the South and North Poles, Mr. Kunches said.

"The magnetic poles in both hemispheres are most exposed to charged particles that come from solar wind," he said.

Airlines with international flights between North America and Asia have been notified of the solar wind, which has been known to interfere with high-frequency radio communications, Mr. Kunches said.

NOAA earlier identified the first solar blast as a category 2 or category 3-level solar storm, with 1 being mild and 5 suggesting an extreme storm, said Tom Bogdan, director of the agency's Space Weather Prediction Center.

Mr. Bogdan said that solar blasts are like "tsunamis in space" and that they can either "ride gracefully" over Earth or create turbulence in Earth's magnetic field, which can disrupt satellite communications.

Scientists expect the frequency of these kinds of events to increase over the next two to three years.

Write to Cassandra Sweet at cassandra.sweet@dowjones.com