On December 17, 2024, a powerful coronal mass ejection (CME) erupted from a sunspot located on the far side of the Sun, sparing Earth from potential geomagnetic storms. Experts suggest that had this CME been directed towards our planet, it could have triggered one of the strongest geomagnetic storms in decades, with effects akin to the historic Carrington Event of 1859, which caused widespread disruptions to telegraph systems.
The solar flare, recorded at a speed of 3,161 kilometers per second—approximately 1% of the speed of light—would have reached Earth in about 18 hours, significantly faster than typical solar wind, which usually takes a couple of days. This CME's expansive nature was captured by the LASCO coronagraph aboard the SOHO spacecraft, illustrating its dramatic release of energy.
Dr. Ryan French, a solar astrophysicist at the National Solar Observatory in the UK, explained that the sunspot responsible for this event remains on the Sun's far side, making it impossible to assess its potential for future activity. Sunspots are cooler, darker areas on the solar surface, and their associated magnetic fields can lead to explosive energy releases when they reconnect—a process known as magnetic reconnection.
While the recent CME missed Earth, the sunspot will soon rotate into view, raising the possibility of future solar events. Dr. French warns that although such events are statistically unlikely to reach 'Carrington-level' intensity, they can still disrupt technological infrastructure. For instance, a similar CME in 2003 caused power outages in South Africa and Sweden, highlighting the risks associated with solar activity during the solar maximum phase.
As the Sun approaches its peak activity, the frequency of solar flares and CMEs is expected to increase, potentially leading to geomagnetic storms and auroras at lower latitudes than usual.