A stealth solar storm occurred on November 20, catching many off guard. This event led to stunning auroras being sighted in areas like Maine and Denmark.
Typically, solar storms, especially coronal mass ejections (CMEs), make a loud entrance. They can produce bright flares and sudden bursts in ultraviolet light. Scientists use instruments called coronagraphs to spot these explosive events. In contrast, stealth CMEs are quiet and hard to track, often only noticed after they reach Earth and alter solar wind conditions.
On that November day, NOAA’s Space Weather Forecasters reported unusual solar wind activity. The magnetic field strength surged from a usual range of 4-6 nanoteslas to 18 nanoteslas around 9:20 a.m. EST, while solar wind speeds increased to between 400-500 km/s. This spike hinted at the presence of a stealth CME.
Space weather expert Tamitha Skov noted the return of such stealthy storms on social media, emphasizing their elusive nature. Only after their arrival can we discern their impact, leading to minor geomagnetic storming, especially in higher latitudes. Interestingly, some stealth CMEs can cause significant disruptions when they occur alongside faster solar wind streams.
The auroras reported on the night of the 20th were likely due to this stealth CME combined with effects from the fast-moving solar wind. Photos shared online showed spectacular displays of red and purple lights across the skies.
Stealth CMEs are essential to understand. Research shows they can originate from seemingly quiet areas on the sun, making them a challenge for forecasting. Their faint signatures often require various observations to detect.
Historically, conversations about solar activity have increased as we near a solar minimum phase, which means less frequent but possibly impactful storms. As we track our sun’s behavior, knowing about these stealth CMEs can help us prepare for their surprises.
For more on CME activity and its effects on Earth, check information from NOAA’s Space Weather Prediction Center.
