The storm occurred on the Sun at 4.24 a.m. Wednesday.
“The magnetic field orientation needed to cause strong geomagnetic storming finally occurred overnight, so although it got off to a slow start, levels have reached what was predicted,” the NOAA’s Space Weather Prediction Center said.
Strong geomagnetic storms can wreak havoc on satellites and have even knocked out power grids on Earth, as occurred in Quebec in 1989.
The current storm caused the European Space Agency’s Venus Express probe to temporarily malfunction shortly after the occurrence of the flare, known as a coronal mass ejection (CME), but controllers say they have now restored the spacecraft to normal operation.
“The CME was the second largest in the current 11-year solar cycle and the largest so far this year,” Sergei Bogachev, a specialist at Russia’s Laboratory of Solar X-ray Astronomy told RIA Novosti.
“A G4 event occurred earlier in the cycle (last year), so this is a major event, but not a record one for the cycle,” he said.
The kp index used to measure geomagnetic activity initially rose to 5 units following the March 7 CME, based on data from ground stations.
That is considered the minimum level to qualify as a geomagnetic storm. It remained at 5 kp for about nine hours, then dropped to 4 kp only to begin rising again four hours later.
It measured more than 7 kp Friday evening in Moscow, which corresponds to a “strong” storm according to the NOAA scale.
Solar storm gains strength
- Intro-text: A magnetic storm that is being felt on Earth due to a huge solar flare on the Sun has now intensified to G3 (strong), the US National Oceanic and Atmospheric Administration (NOAA) said.