A strong geomagnetic storm is on its way to Earth this week after two solar flares erupted from a sunspot region pointed almost directly at Earth. The second of the two was a low-end X-class flare — the most intense type of flare on the classification scale.
After Tuesday’s minor solar fare from sunspot region AR 2158, the same location emitted an X1.6-class flare on Wednesday, prompting the NOAA’s Space Weather Prediction Center to up their forecasts for the geomagnetic storm expected to arrive here on Earth on Friday. A G2 geomagnetic storm watch is in effect for Friday, and a more intense, G3 storm watch is in effect for Saturday, due to the combined effects of the two coronal mass ejections (CMEs).
Geomagnetic storms of this magnitude are not uncommon, but the current solar cycle, in which we are near the maximum, has been relatively quiet. Tom Berger, director of the Space Weather Prediction Center, estimates that a G3-level storm occurs about once a month in the more active, 11-year solar cycles.
However, space weather forecasters were intrigued by the location of these solar flares. “What’s unusual about this event is that the sunspot group producing the flares is right in the middle of the sun,” Berger says. “This is the first time in a while that we’ve had an active sunspot group pointed almost directly at Earth produce two successive major events.”
While the active region is close to the center of the sun, it’s off by just enough that Earth isn’t going to experience the full force of these ejections. Instead, they are expected to brush mostly to the north, or above, Earth, meaning we will endure only a portion of the solar blast.
Impacts from the geomagnetic storms are expected to begin on Thursday night as the first wave of CME arrives. While high frequency radio transmissions in aircraft will likely be impacted, scientists do not expect any other major infrastructure effects, like power grid perturbations or satellite anomalies.
Of course, there will be an enhanced aurora in the northern states, “Montana, Wyoming, and of course the far northeast states like Vermont and New Hampshire. It could be seen as far south as New York,” says Berger. The aurora activity will begin on Thursday night, and will last into Friday night, as well.
While the SWPC is expecting strong storming at the most, Berger says they could be surprised. “This is an inexact field. Scientists are still very active in trying to understand the physics of these things.”