On Monday evening, sky gazers enjoyed a moderate exhibition of the aurora borealis. For those who missed it, there’s a possibility of witnessing it again tonight as a stronger geomagnetic storm is anticipated. The U.S. National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) is predicting an intense geomagnetic storm, following the moderate one on Monday.
The sun has been quite active lately, with numerous sunspots on its surface that can trigger solar flares. These solar flares, which are massive bursts of electromagnetic radiation, can disrupt radio transmissions on Earth. Often, these flares are succeeded by coronal mass ejections (CME), which are large discharges of solar particles traveling rapidly on the solar wind. When these particles interact with Earth’s magnetic field, they produce stunning northern lights, known as aurora borealis.
In this instance, two CMEs were emitted by the sun on August 30 and are now heading towards Earth. According to Tamitha Skov, a space weather physicist and professor at Millersville University in Pennsylvania, the significance of the eruptions was not evident at first. However, a more thorough analysis revealed that the second eruption was more potent than initially thought.
Monday’s geomagnetic storm was classified as G2 on a scale of one to five. The SWPC is forecasting a G3 geomagnetic storm for Tuesday night.
Predicting auroras is notoriously tricky, so there is no guarantee of a show tonight. However, various apps, such as Aurora Alerts and Aurora Now, can inform you if the auroras are visible in your vicinity.
Many people may recall the spectacular northern lights displays on May 10, 2024, and October 10, 2024, when both storms reached G5 intensity. Originally forecasted as G3 or G4, this serves as an example of the challenges in accurate forecasting. On both occasions, the northern lights were visible across Canadian and U.S. cities, extending as far south as Mexico.
Regarding the current storm forecast, the first impact was felt on Monday, with the second anticipated for Tuesday. Skov mentioned that Earth is likely to face consecutive solar storms, with severe conditions expected at high latitudes. Canadians, particularly in high latitudes, are in for a treat, while cities in mid latitudes have a 50% chance of experiencing a strong geomagnetic storm in the next 24 hours, increasing to 85% for those in high latitudes.
Various factors need to align for auroras to be visible in mid-latitudes, including the speed of the solar wind and the orientation of the auroral oval, which determines the southern extent of the auroras. NOAA uses the Kp index, ranging from one to nine, to gauge the intensity of geomagnetic storms. Typically, for mid-latitudes, a Kp of 6 or higher is necessary to witness auroras unless conditions are optimal.
At present, the Kp stands at four, with the auroral oval extending into northern Europe. Canadians are hopeful for a prolonged storm, as favorable magnetic field orientation could lead to a remarkable aurora display.
