"Severe" solar storm could bring Northern Lights to U.S. this weekend
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A strong solar flare (circled) observed on Thursday. Photo: NOAA
The Sun has been emitting "strong" solar flares of high-energy radiation, raising the possibility of communications disruptions but also that the Northern Lights could be seen across parts of the U.S. from Friday evening.
The big picture: That's according to NOAA, which issued a "very rare" Severe (G4) Geomagnetic Storm Watch — the first such alert in 19 years.
Driving the news: "A large sunspot cluster has produced several moderate to strong solar flares since Wednesday," per a statement from NOAA's Space Weather Prediction Center (SWPC) on Thursday.
Between the lines: Such large bursts of plasma from the Sun, known as extreme coronal mass ejections (CME), cause geomagnetic storms when they are directed at Earth.
- CMEs have the potential to harm satellites, impact infrastructure and disrupt communications.
- "What's been quite remarkable is that it's been back to back to back — we've actually had six different eruptions" directed toward Earth, said Bill Murtagh, program coordinator at the SWPC, of the latest solar flares.
State of play: The Sun's activity is measured in 11-year cycles and the current Solar Cycle 25 is "very close to solar maximum, so we can expect frequent activity," said Rob Steenburgh, a space scientist at the SWPC, in an email late Thursday.
- "G4 storms are relatively rare, with about 100 over the course of an 11-year solar cycle," Steenburgh said. "The strongest storms (G5 - extreme) are the most rare, with only 4 during the course of an average solar cycle. We had no G5 events during the last solar cycle."
- Last December, NASA captured an image of what the SWPC said was likely "one of the largest solar radio events ever recorded."
- "Bursts of similar magnitude occurred yesterday," Murtagh said in a phone interview late Thursday. But unlike the December event that disrupted air traffic communications in places like Seattle and Northern California, these ones occurred about 4am, so U.S. air traffic control was not affected.
What we're watching: "Additional solar eruptions could cause geomagnetic storm conditions to persist through the weekend," according to the SWPC.
- "Geomagnetic storms can also trigger spectacular displays of aurora on Earth. A severe geomagnetic storm includes the potential for aurora to be seen as far south as Alabama and Northern California."
- Northern tier U.S. states bordering Canada should have a good chance of seeing the aurora borealis, or Northern Lights, if conditions reach G4 levels, Murtagh noted.
Go deeper: Sun's strongest solar flare in years knocks out radio frequencies
Editor's note: This article has been updated with comment from Bill Murtagh, program coordinator at NOAA's Space Weather Prediction Center, and Rob Steenburgh, a space scientist at the SWPC.
