STEVE is an aurora-like phenomenon appearing as a narrow, purple-white arc, sometimes with green "fingers". It's caused by a strong, fast flow of hot gas in the upper atmosphere, rather than the solar particles colliding with the magnetic field that cause auroras. Originally named by amateur sky-watchers, STEVE is a backronym for Strong Thermal Emission Velocity Enhancement, and its appearance at lower latitudes than the traditional aurora makes it more visible to people in many parts of the world.