On 3 October 2015, a Gulfstream V research jet belonging to the National Science Foundation recorded a massive spike in atmospheric radiation while flying over the South Atlantic between Antarctica and the tip of South America. For 11 minutes, its on-board radiation detector watched as levels doubled, as if the aircraft had flown through a cloud of radiation.
That was not the only incident. Since 2013, airborne detectors have recorded 57 similar radiation bursts, each lasting between ten minutes and an hour.
The observations have raised significant questions, not least about the risks to aircrew and the safe operation of airborne electronics. But most of all, scientists want to know what causes these radiation bursts.