The solar storm which hit Earth on Friday and Saturday was the most severe to affect South and Southern Africa in 21 years, the South African National Space Agency (SANSA) has reported. The SANSA Space Weather Centre, located at the SANSA Space Science facility in Hermanus, in the Western Cape, issued a G5 geomagnetic storm warning, as well as several G4 warnings, over the period of the event. G5 is the highest rating on the international scale, and signals an extreme storm. It was the first time since 2003 that SANSA had issued a G5 warning.

“Although the likelihood of such a storm occurring is quite low, the severity of the impacts on technological systems can be very high,” pointed out SANSA Space Science acting executive director Jon Ward. “The energy and transport sectors are particularly vulnerable at the moment. Space weather is a global phenomenon, [but] the impacts are regional and vary greatly, depending on the time of arrival of the storm and whether the region is experiencing day or night.”

A geomagnetic storm occurs when a coronal mass ejection (CME) from the Sun hits, and interacts with, Earth’s magnetic field. A CME is a large expulsion of plasma and magnetic field from the Sun’s corona. The US National Oceanic and Atmospheric Administration (the agency responsible for space weather forecasting in the US) reports that slow CMEs travel at speeds of less than 250 kilometres a second (km/s), but fast ones can move at almost 3 000 km/s.

“SANSA’s Space Weather Centre was purposely built to focus on the impacts in the Africa region,” explained Ward. “This storm highlights the importance for businesses using technologies that are susceptible to the adverse effects of space weather to include space weather in their risk planning. The world is so dependent on technology now and everything is so integrated with devices getting smarter and interconnected. We are so much more susceptible to disruptions due to solar events and space weather than we were 20 years ago. Awareness of space weather is critical in planning to protect against potential losses.”

SANSA’s 24/7 Space Weather Centre was launched in November 2022. The agency had previously been actively studying space weather, and issuing space weather forecasts (although not on a 24/7 basis) since 2009. This is the only accredited space weather centre in Africa.

A side effect of space weather events is that they trigger major auroral events, greatly stimulating both the northern hemisphere’s Aurora Borealis and the southern hemisphere’s Aurora Australis. During this storm, auroras were observed over Gansbaai in the Western Cape province, among other locations. (Gansbaai is a coastal town lying south-southeast of, but not far from, Hermanus, and about 113 km south-east of Cape Town.)