On Thursday, a significant solar outburst impacted Earth, leading to a "severe" G4-class geomagnetic storm. This event, triggered by an enormous mass of charged particles ejected from the sun on October 8, has generated the potential for auroras to be visible much farther south than usual, possibly reaching areas like California and Alabama.
Impact on Power Grids and Communications
The National Oceanic and Atmospheric Administration (NOAA) has warned that this storm could disrupt power grids and communications systems, especially those weakened by the recent Hurricanes Helene and Milton. The auroras are expected to light up the northern half of the U.S., with the possibility of sightings in lower latitudes. NOAA has been in contact with federal and state officials to discuss the potential impacts on hurricane recovery efforts.
Potential for Intensification
There is a chance that the storm could intensify into "extreme" G5-class conditions, similar to a notable solar event in May that resulted in auroras visible as far south as Florida. As the situation evolves, NOAA will provide ongoing updates regarding the storm's progression.
Nature of Solar Flares and CMEs
The solar outburst itself is the result of a coronal mass ejection (CME) linked to a powerful X 1.8-class solar flare, which is the strongest type of flare emitted by the sun. Solar flares occur when magnetic-field lines on the sun become tangled and snap back into place, sometimes releasing fast-moving blobs of plasma that take days to reach Earth. Upon contact, these CMEs can cause disturbances in Earth's magnetic field, leading to geomagnetic storms and stunning auroras. The severity of these storms is measured on a scale of 1 to 5.
Tips for Aurora Chasers
For those hoping to catch a glimpse of the northern lights, experts suggest moving to locations away from city lights to improve visibility. While no special equipment is necessary to see the auroras, using a smartphone camera can enhance the colours, making for a more vivid experience.
Solar Cycle Context
Solar flares, CMEs, and auroras typically increase in frequency during the solar maximum phase of the sun's approximately 11-year activity cycle. Although this cycle was initially expected to peak in 2025, some scientists believe we might already be witnessing its onset.
Comet C/2023 A3 at Risk
Interestingly, the CME also poses a potential threat to the bright comet C/2023 A3 (Tsuchinshan-ATLAS), which is currently making its closest approach to the sun in 80,000 years. Observers are curious to see whether the solar eruption has affected the comet's tail, similar to an earlier event involving another comet. The outcome will become clear when C/2023 emerges from behind the sun this weekend.
