High-energy proton flux over the polar regions

Each star tracker consists of three cameras pointing in different directions. These cameras are sensitive to ionising radiation: when an energetic particle hits the sensor, it appears as a white spot. Analysts have been able to produce data on particle fluxes, in particular detecting impacts from protons with energy levels of Megaelectronvolt (MeV), higher than 100 MeV.

While the South Atlantic Anomaly (SAA) is the main source of penetrating ionising radiation, magnetic storms can lead to a temporary enhancement of high-energy particles in the polar regions, due to particles being injected into the magnetosphere and becoming trapped. This image shows the particle flux over the polar regions on 12 November, 2025.

Read full story: Swarm detects rare proton spike during solar storm