On May 11, 2024, the Sun unleashed a powerful X5.8-class solar flare, sending high-energy protons toward Earth! This triggered Ground Level Enhancement (GLE) 74 — a surge of radiation detected by both space-based satellites and ground-based neutron monitors.
The study by Papaioannou et al., conducted as part of the Horizon Europe project SPEARHEAD, showed that GLE74 reached a maximum particle energy of approximately 1.6 GeV, while the release time of solar energetic particles (SEPs) with 500 MeV energy was estimated to be around 01:21 UT.
Remarkably, a strong SEP flux was observed from the anti-Sun direction, with a broad angular distribution — indicating that the particles propagated under the influence of structures in a disturbed magnetic field. Comparisons with previous GLEs revealed that GLE74 was typical in terms of solar eruption dynamics.
It is worth noting that GLE74 occurred immediately after one of the 10 strongest geomagnetic storms recorded since 1957, highlighting the rare intensity of solar activity during that period.
More info: https://link.springer.com/article/10.1007/s11207-025-02486-0