Unusual red northern lights over Japan suggest some solar storms are stronger than we thought

A rare crimson aurora glowing over northern Japan may be a sign that some solar storms are more powerful than scientists once believed. Researchers studying faint red auroras observed above Japan in June 2024 found that the displays stretched far higher into Earth's atmosphere than expected, reaching altitudes between roughly 310 and 500 miles (500 to 800 kilometers) — which is unusually high for a storm that was not considered especially severe by conventional geomagnetic indices, according to a statement from Hokkaido University. The discovery suggests that even "moderately intense" geomagnetic storms — which are a disturbance in Earth's magnetic field caused by charged particles and magnetic energy from the sun — may carry far more energy than previously thought, challenging scientists' understanding of how these space weather events develop and how their strength is measured. Low-latitude aurora observed on June 28, 2024, in Yoichi, Hokkaido, Japan, shows a rare red glow stretching across the night sky during a geomagnetic storm that scientists say reached unexpectedly high altitudes in Earth's upper atmosphere. (Image credit: Tomohiro M. Nakayama) "I was really surprised because I didn't expect such tall auroras to appear even during moderately intense storms," Tomohiro M. Nakayama, lead author of the study, said in the statement. …