Researchers have found that faint red auroras visible from Japan can extend far higher into the atmosphere than previously thought, even during moderate solar storms.
A study from Hokkaido University and the Okinawa Institute of Science and Technology measured the auroras at altitudes of 500 to 800 kilometers. The findings come from observations of five events recorded in Hokkaido between June 2024 and March 2025. Scientists combined satellite data with images taken by citizen observers to map the structures along magnetic field lines.