The Sun is having a moment, and the Earth just got caught in the crosshairs of a coronal mass ejection. According to the US National Oceanic and Atmospheric Administration (NOAA), the solar outburst resulted in a moderate geometric storm, with “disturbed conditions” expected to continue for the next day or so.
Coronal mass ejections are large discharges of plasma and magnetic fields from the Sun’s corona. They can be emitted in any direction, and occasionally get blasted straight towards our home planet, like the one that occurred on March 10.
The ensuing storm can produce varying levels of disruption, depending on its strength. In most cases, the only noticeable effect is an increase in the intensity of the aurora borealis and aurora australis, which can be observed from lower latitudes than would normally be the case.
Typically, these aurorae are only visible at high latitudes, close to the north and south poles, and arise when charged particles from the Sun interact with Earth’s magnetic field. When a coronal mass ejection occurs, an increased number of these particles reach our atmosphere, resulting in greater ionization of molecules and a more spectacular light show.
Northern Hemisphere aurora forecast until March 16. Video credit: Met Office
According to the NOAA, a G2 level geometric storm hit the Earth on March 13. This corresponds to a “moderate” storm, which is powerful enough to cause voltage issues for high-altitude power systems and pose problems for spacecraft by generating an increase in drag. Aurorae have been observed as far south as New York during previous G2 level solar storms.
For reference, the most extreme geometric storms are classed as G5, and have been known to cause entire power grids to collapse and aurorae to become visible all the way down in Florida.
While the current solar storm is nowhere near that strong, it has brought the Northern Lights to parts of the UK. According to the UK Met Office, the nightly spectacular may continue to linger in parts of Scotland for the next day or so, with further mild solar storms expected until March 15.
The Sun's coronal mass ejection on March 10, 2022.Video credit: NASA/SDO
So far, 2022 has seen more than its fair share of outbursts from our star, and while life down here on Earth has remained largely unaffected, conditions in orbit have been somewhat chaotic. Last month, for instance, dozens of Starlink satellites were struck by a geometric storm shortly after launching, knocking them off course and causing them to burn up in Earth’s atmosphere.
Our Sun has a natural 11-year cycle of activity, measured from minimum (the least activity) to maximum (the most active, with sunspots, flares, and storms) and back to the minimum. Solar Cycle 25, the 25th since reliable records of solar activity began, started in December 2019 – so we're heading towards a solar maximum of peak activity in 2025.
With three years to go until the next solar maximum, more events like these are to be expected in the near future, although whether or not the Sun produces anything more dramatic than a G2 storm remains to be seen.