Two coronal mass ejections—eruptions from the sun that send a cloud of charged particles into space—are hurtling toward Earth right now. As they enter the Earth’s magnetic field, they could create magnetic storms that interfere with radio transmissions, GPS, and even power grids. But scientists from the National Oceanic and Atmospheric Administration say the risk is low. This time.
When the CMEs encounter the Earth’s magnetic field, they stretch and distort it as they pass. It releases energy in the process of recovering, which is what causes auroras and radio communications problems. For more watch Slate’s vide explainer:
On Monday night, a minor solar flare gave off a first magnetic cloud. Then on Wednesday afternoon, a major flare from the same sunspot region gave off a bigger CME. Thomas Berger, the director of the Space Weather Prediction Center at NOAA, said that both are aimed at the Earth. The first burst is forecast to hit Earth sometime Thursday night, and the second should arrive around midday on Friday.
“On a geomagnetic storm scale of 1 to 5, we’re currently expecting the CME impacts to cause G2, moderate, to G3, strong, geomagnetic storming,” Berger said. But there’s good news: “ [The] effects are expected to be manageable and not cause any major disruption to power transmission. The grid operators have been notified … and FEMA has been notified of these events as well just in case.”
NOAA uses observation of the sun and mathematical modeling to predict when magnetic storms will hit. And about an hour or so before the storms hit, they pass NASA’s ACE satellite, which is upstream from Earth and therefore encounters CMEs first. At that point, NOAA can obtain specific measurements about attributes like the direction of the cloud’s magnetic field, which plays a role in how intense the magnetic storms are when the CMEs interact with the Earth’s magnetic field.
Sarah Gibson, a senior scientist at the National Center for Atmospheric Research, says it’s significant that the CMEs are coming one after the other. “Our simulations are starting to show us that if you have one of these coronal mass ejections and then another one not long afterwards, [the first] is like a snowplow making a path and it makes it possible for the second one to become especially fast.”
Berger said that this confluence of events could possibly cause storms as intense as G4 (out of 5), especially at the Earth’s poles, but he emphasized that NOAA is not forecasting a doomsday scenario. “We don’t expect any unmanageable impacts to national infrastructure from these solar events at this time, but we are watching these events closely,” he said. “More pleasantly, we do expect these storm levels to cause significant auroral displays across much of the northern U.S. on Friday night. With clear skies currently forecast for much of these regions this could be a good opportunity for auroral sightings.”