If you’re in the Northern Hemisphere, look up at the sky tonight for a spectacular light show. Two coronal mass ejections from the Sun on March 15 hit the Earth Tuesday, generating a severe geomagnetic storm. The storm has caused an Aurora Borealis, or the northern lights, but also threatens to disrupt GPS satellites and electrical grids.
Residents in Minnesota, Wisconsin, Alaska, Washington, North and South Dakota reported seeing the lights before dawn Tuesday morning. The storm’s effects will linger for the next 12 to 36 hours, causing beautiful lights in the darkened skies as far south as the central United States, said Thomas Berger, director of the Space Weather Prediction Center.
When bubbles of gas erupt on the Sun, they throw off large clouds of magnetic field and a wave of protons and electrons into space, Berger said. It’s called a coronal mass ejection. On Sunday, two coronal mass ejections happened in quick succession and merged, he said.
When the wave of electrons, protons and magnetic field hits the Earth, it is similar to bringing together opposite ends of a magnet, Berger said. The magnetic field from the coronal mass ejection interacts with the Earth’s magnetic field and changes electrical currents on the ground.
The flood of electrons and protons to the atmosphere generates the aurora borealis, creating spectacular colors in the night sky. Depending on the storm’s severity, it can disrupt instruments in airplanes, space stations, cause power outages and disrupt GPS signals.
At 10 a.m. Eastern Time on Tuesday, NOAA’s Space Weather Prediction Center recorded G4 levels for approximately an hour. That’s on a scale from G1 to G5, with G5 considered the most severe. The center hasn’t recorded a storm this intense since 2013, said Bob Rutledge, forecast lead at the Space Weather Prediction Center.
But the wave of charged electrons, protons and magnetic field has to travel 93 million miles to reach the Earth, a relatively small target, Berger explained. The center’s models predicted that the storm would glance off of the Earth, generating a G1 level storm for today, Rutledge said. Now, it appears the storm offered a more direct hit to the planet, he said.
The storm could still cause power fluctuations, but no outages or failures have been reported yet, Berger said in a press briefing this afternoon. The currents from the solar storm could be strong enough to disrupt GPS devices, he warned.
The G4 storm appears to be subsiding, but it’s hard to predict what it will do over the next several hours, Rutledge said. It’s likely we will still be in the midst of the storm for the next 12 hours, and the effects could linger as long as 36 hours, he said.
NOAA has a satellite, ACE, a million miles from Earth that acts a buoy to predict these storms, said Brent Gordon, space weather services branch chief at the Space Weather Prediction Center. A new satellite, DSCOVR, was launched a month ago to replace the aging satellite, but it hasn’t reached its destination yet. When DSCOVR takes over in late summer, scientists will hopefully be able to better predict these storms, Gordon said.
To find out if the aurora is visible where you live, check out the Space Weather Prediction Center’s Aurora Forecast.