Geomagnetic Storm Watch Issued for August 27-28

The US National Oceanic and Atmospheric Administration (NOAA) has issued a geomagnetic storm watch covering August 27-28, after a powerful solar flare erupted from the sun and sent material hurtling toward Earth.

According to NOAA's Space Weather Prediction Center, the flare released one or more coronal mass ejections (CMEs) — massive clouds of magnetised plasma expelled from the sun's outer atmosphere, or corona — that are now travelling through space in Earth's direction.

CMEs typically take one to three days to reach Earth, depending on their speed, which is consistent with NOAA's forecast of possible impacts arriving on August 27 and 28. When these clouds of solar material collide with Earth's magnetosphere, the region of space dominated by the planet's magnetic field, they can trigger a geomagnetic storm.

Geomagnetic storms occur when solar wind and CME material disturb Earth's magnetic environment, sometimes disrupting satellite operations, GPS signals and power infrastructure on the ground. However, they also energise particles in the upper atmosphere, producing the vivid aurora displays commonly known as the northern lights, or aurora borealis, in the Northern Hemisphere.

Under the influence of a strong enough storm, the aurora can become visible at much lower latitudes than usual, extending the viewing zone well beyond its typical range near the poles. NOAA's watch suggests conditions could favour a particularly dazzling display, with Friday, August 27, highlighted as a likely peak period for visibility.

Sky-watchers hoping to catch the phenomenon are generally advised to seek dark locations away from artificial light, with clear, unclouded skies offering the best chance of observation. The precise intensity of the storm — and therefore how far south the aurora might be seen — will depend on the exact speed, density and magnetic orientation of the incoming CMEs, factors that solar physicists will continue to refine as the event approaches.

NOAA has stated that it will keep monitoring solar activity and update its forecasts as new data becomes available, a standard practice for geomagnetic storm watches, which are issued in advance to give satellite operators, power companies and the public time to prepare for potential effects.