One-Two Punch From the Sun Knocks Out Radios

X9-level solar flare was preceded by weaker one on Wednesday
By Jenn Gidman,  Newser Staff
Posted Sep 7, 2017 8:44 AM CDT
Most Powerful Solar Flare in Decade Knocks Out Radios
Wow.   (NASA)

In what one space scientist says is "just part of living with a star," two solar events rocked the cosmos Wednesday, one of them strong enough to knock out radio communications for up to an hour. Scientific American reports on a pair of X-class solar flares (the most powerful type of flare): an X2.2 that burst out of a sunspot at around 5:15am EDT, followed by a much stronger X9.3 flare at 8:02am, per the NOAA's Space Weather Prediction Center. That second flare was a doozy: It was the first X9-level flare since 2006, causing a "wide area of blackouts" to high-frequency radio with "loss of contact for up to an hour over [the] sunlit side of Earth," as well as the degradation of low-frequency radio, which is used for navigation, for about an hour.

"Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however—when intense enough—[it] can disturb the atmosphere in the layer where GPS and communications signals travel," NASA notes. Solar scientists say the sun has undergone changes over the past three decades: There's been an odd sunspot dearth during the low-activity periods of 11-year solar cycles, magnetic field distribution has thinned, and even the sun's rotation rate has shifted. "It's clear that we are in unusual times," an expert tells Newsweek. It doesn't look like the show is over: A geomagnetic storm warning is in place for the next few days after a coronal mass ejection—a large explosion of plasma and magnetic field that often accompanies a solar flare—that could cause auroras later this week. (Solar flares nearly caused a nuclear war in the late '60s.)

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