What Are Solar Proton Events?
Solar proton events (SPEs) are periods when high-energy protons from the Sun (from flares or CME shocks) reach Earth in elevated fluxes. They are a type of solar energetic particle (SEP) event. SPEs can last hours to days and pose a radiation hazard for satellites, astronauts, and aviation on polar routes. NOAA issues radiation storm alerts (S1–S5 scale). Cosmic Radar shows space weather and Kp in the daily report; for radiation storm details see NOAA SWPC.
Sources and further reading
- NOAA – Solar radiation storm – SPE and S-scale
- NASA Space Weather – Energetic particles