A solar storm was due to arrive Saturday morning and last through Sunday, slamming into Earth's magnetic field. Scientists said it will be a minor event and they have notified power grid operators, airlines and other potentially affected parties.
"This isn't the mother of all anything," said forecaster Joe Kunches at the government's Space Weather Prediction Center in Boulder, Colo. "We don't see any ill effects to any systems."
The storm began Thursday when the sun unleashed a massive flare that hurled a cloud of highly charged particles racing toward Earth at 3 million mph. It was the sixth time this year that such a powerful solar outburst has occurred; none of the previous storms caused major problems.
In severe cases, solar storms can cause power blackouts, damage satellites and disrupt GPS signals and high-frequency radio communications. Airlines are sometimes forced to reroute flights to avoid the extra radiation around the north and south poles brought on by solar storms.
In 1989, a strong solar storm knocked out the power grid in Quebec, causing 6 million people to lose electricity.
Juha-Pekka Luntama, a space weather expert at the European Space Agency, said utility and navigation operators "will certainly see something but they will probably find ways to deal with any problems" from the incoming storm.
The storm is part of the sun's normal 11-year cycle of solar activity, which is supposed to reach peak storminess next year.
There's a bright side to stormy space weather: It tends to spawn colorful northern lights as the charged particles bombard Earth's outer magnetic field. Shimmering auroras may be visible at the United States-Canada border and northern Europe this weekend, Kunches said.
AP writer Frank Jordans in Berlin contributed to this report.
NOAA Space Weather Prediction Center