STEVE may be even less like typical auroras than scientists thought
Horizontal green streaks that often appear in the sky glow can’t be formed by electron showers
The sky glow known as STEVE is a cousin to the auroras. Its bright smear of purple is formed by a torrent of charged particles rushing across the atmosphere. That plasma heats surrounding air particles to make them glow purple.
NASA Goddard Space Flight Center, courtesy of Krista Trinder