A geomagnetic storm lit up the night sky in parts of the US during the first weekend in October. South Africa’s National Space Agency (Sansa) told reporters that the storm had originated from a solar flare “that erupted from sunspot 3842 on October 3”. It said this was the strongest Earth-facing solar flare recorded by Sansa in the past seven years and that the eruption briefly affected high-frequency radio communications, “resulting in a total radio blackout over the African region which lasted for up to 20 minutes”. What is a geomagnetic storm? The Conversation Africa asked Sansa’s Amoré Nel, who…