Overview
- A peer-reviewed paper published November 20, 2025 in Earth, Planets and Space reports continuous observations from Japan’s Arase satellite combined with ground-based GPS measurements.
- During May 10–11, 2024, the plasmasphere’s outer edge fell from about 44,000 km to roughly 9,600 km within nine hours, shrinking to around one-fifth of its typical size.
- Recovery required more than four days—the slowest since Arase began monitoring in 2017—because a negative storm depleted ionospheric electron density and altered atmospheric chemistry.
- The compressed magnetic environment enabled unusually low-latitude auroras observed in Japan, Mexico, southern Europe, Uluru and Townsville in Australia, and as far south as Florida.
- Infrastructure effects included degraded GPS accuracy, radio communication outages, and satellite anomalies, highlighting needs for better forecasting and space-system resilience near solar maximum.