Purple streaker Steve a mystery of the night sky

Given a 'down to earth' nickname for the time being, a newly found fast-moving gas ribbon is fascinating astronomers

A mysterious streak of purple light spotted by aurora watchers adds to a growing list of upper atmospheric phenomena. Previously spotted electrical effects have been called elves, sprites and gnomes; the newcomer has the less fairytale name of Steve.

The name was bestowed by the Alberta Aurora Chasers, an online skywatching group who first noticed the phenomenon. Initially it looked like a faint contrail, but longer exposures showed that it was luminous with a distinctive purple colour.