Aurora-like STEVE phenomenon has a 'secret twin' that appears only before dawn, study finds

A wispy purple ribbon stretches across the night sky.

A purple ribbon of light in the sky known as "STEVE" appears to have a long-lost twin. 

This isn't the plot of a space soap opera; it's a finding from a trio of European Space Agency satellites known as Swarm. The research, published in the journal Earth, Planets and Space in April, finds that whereas STEVE appears before midnight and flows from east to west, a twin phenomenon occurs in the predawn hours, flowing in the opposite direction.