Swarm Scientific Highlights
Steve over the picket fence
27 November 2019
Strange ribbons of purple light that appeared in the sky – known as Steve – became the subject of debate in 2017, as their origins were unbeknown to scientists. Now, photographs of this remarkable phenomena have been studied to understand their exact position in the night sky.
Steve was first spotted by citizen scientists who posted photos of the unusual purple streaks of light in the Aurora Chasers Facebook group. Sometimes Steve was seen accompanied by smudges of green lines – nicknamed 'picket fences' owing to their appearance.
Unsure of what it was and how to refer to it, the name 'Steve' was chosen from a scene from the animated movie Over the Hedge, where characters choose a name for something unknown to them.
Scientists were able to compare ground sightings with data from ESA's Swarm mission, which showed that Steve actually comprises a fast-moving stream of extremely hot atomic particles.
Since then, scientists have been trying to better understand the science behind the phenomenon.