The most powerful solar storm in nearly six years has hit the Earth, but space weather forecasters did not see it coming.
The storm made auroras visible as far south as New Mexico in the U.S., and forced spaceflight company Rocket Lab to delay a launch by 90 minutes, the company announced on Twitter.
The geomagnetic storm was marked as a grade 4 on on the 5-grade scale used by the U.S. National Oceanic and Atmospheric Administration (NOAA) to assess the severity of space weather events.
Geomagnetic storms are disturbances to Earth’s magnetic field caused by solar material from coronal mass ejections (CME) — large expulsions of plasma and magnetic field from the sun’s atmosphere.
The latest storm, which took place on Friday, was triggered by a “stealth” CME which is difficult to detect.
NOAA’s National Space Weather Service originally said on Wednesday a moderate grade 2 storm would hit the Earth on March 24. This was upgraded to a grade 4 storm at 00:41 a.m. EDT (04:41 a.m. GMT) on March 24.
U.S. space weather forecaster Tamitha Skov told Space.com such storms launch slowly and are very difficult to observe leaving the sun‘s surface without specialised training.
“This is why they are the cause of ‘problem geomagnetic storms’ like the G4-level storm we are in now,” Skov continued.
Geomagnetic storms are ranked by the NOAA on a scale of one to five. Grade 1 storms could cause an increase in auroral activity around the poles and minor fluctuations in power supplies. Grade 5 storms can disrupt telegraph services all over the world and trigger bright and powerful auroras.
A grade five storm occured in September 1859, and auroras were visible as far south as the Bahamas.
Strong geomagnetic storms can also affect spaceflight as they increase the density of gases in Earth’s upper atmosphere, thereby increasing the drag on satellites and other spacecraft.
In February 2022, Elon Musk’sSpaceX lost up to 40 brand-new Starlink satellites when they failed to reach orbit after being launched into a minor geomagnetic storm.
