This strange shimmering ribbon of purple light, which was discovered in 2016, is known as Steve. It’s a weird feature of the aurora which has mystified astronomers for quite some time, but now – thanks to the European Space Agency’s Swarm mission – more is known about this strange phenomenon.
Researchers were first made aware of Steve when members of the Aurora Chasers Facebook group started posting photos of unusual streaks in the night sky. Aurorae are made when our magnetic field guides energy and atomic particles in the solar wind around Earth and towards the north and south poles. When these particles crash into the atoms and molecules of the upper atmosphere, waves of luminous green light of the aurora borealis and aurora australis appear.
While Steve can appear at the same time as an aurora, it’s found to be quite a different beast. While standard aurorae paint the sky in greens, blues and reds and can last for hours, Steve remains in the sky for a relatively short time.
Steve’s made through the same general process as a normal aurora, travelling along different magnetic field lines and appearing at much lower latitudes.