Magnetic eruptions on the Sun on Tuesday and Wednesday released two huge bursts of lights — two of the largest solar flares over the last five years — and accelerated a blob of high-speed particles headed toward us. As the charged particles slam the Earth’s magnetic field at more than a million miles per hour and are funneled toward the north and south poles, they generate the nighttime light now known as auroras or northern and southern lights.
Giant solar storms can wreak havoc on satellites and power grids. One storm knocked out power in a large area in Quebec in 1989. The current storm, which started Thursday morning, is not nearly large enough to cause that much trouble.
“At this point it’s a minor storm,” said C. Alex Young, a senior solar physicist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “It’s not going to be that big even if the levels increase a bit. This is really not something to be concerned about.”
Nevertheless, concern did ensue after NASA issued a statement on Wednesday saying that two large solar flares could send “a severe geomagnetic storm” toward Earth that could cause “possible disruption to high frequency radio communication, global positioning systems and power grids.”
That announcement caused a storm of its own, sparking numerous hyperbolic news reports about possible dangers to air travel and communications systems from large clouds of charged particles rushing at the Earth.
The storm particles started shaking the Earth’s magnetic field Thursday morning, the disturbance was rated only “minor,” a 1 on the 1-to-5 scale used to describe the intensity of such storms. The intensity did not crescendo to the “strong” threshold as had been predicted. A similar-size storm also hit Earth in late January.
Elsewhere, closer to the Sun, the storm was felt more acutely. The splash of intense radiation temporarily blinded the European Space Agency’s Venus Express spacecraft.
There has been a five-year lull in strong solar storms because the ferocity and pace of the Sun’s flares and magnetic eruptions rise and fall on an 11-year cycle, and the Sun has only recently emerged from its slumber and started generating new solar flares.
“We’re getting the first few snowfalls of the year, so to speak,” said Robert Rutledge, lead of the forecast office at the Space Weather Prediction Center in Boulder, Colo., part of the National Oceanic and Atmospheric Administration.
During the course of a typical cycle, some 200 solar storms as strong as Thursday’s will hit Earth. Even though the current cycle appears quieter than usual, such storms could strike Earth a few times a week when the cycle peaks in the next year or so.
If the cycle matches the usual pattern, about a tenth as many of the solar storms — 10 to 20 — would reach the stronger, “severe” level and one or two would be described as “extreme.”
It is the most powerful storms that generate real worry. In addition to knocking out power grids, the larger solar storms can also damage satellites or pose a health hazard to astronauts on the International Space Station.
“I don’t think people should really be concerned” unless an extreme solar storm is headed toward Earth, Dr. Young said. “We want the general public to be aware of it and know what’s going on, but at the same time not lose sleep over it.”
