Transient luminous events are short-lived optical phenomena associated with thunderstorms that occur well above the altitudes of normal lightning and storm clouds. This lightning that occurs in the upper atmosphere is believed to be a type of luminous plasma that is electrically induced.
The transient luminous events have only been recently documented by researchers using low-light-level television technology. Usually, they are described using fantasy-inspired names such as sprites, elves, pixies, gnomes, and trolls.
The lower orbit of the space station is ideal for studying the phenomenon. The image taken by Pesquet represents a single frame from a timelapse over Europe that shows a thunder strike with a glowing blue circle in the upper atmosphere. He described the occurrence as being "very rare."
"What is fascinating about this lightning is that just a few decades ago they had been observed anecdotally by pilots and scientists were not convinced they actually existed. Fast forward a few years and we can confirm elves, and sprites are very real and could be influencing our climate too," reads the caption of the picture.
ESA astronaut Andreas Mogensen was the first to capture the electrical phenomena clearly during his mission on the ISS in 2015. Back then, he was assigned to record thunderstorms using the most sensitive camera on the orbiting lab in order to detect these brief bursts of light.
Mogensen captured multiple miles-wide blue flashes while flying over the Bay of Bengal, including a pulsating blue jet that reached a 25-mile (40-kilometer) altitude.
????A single frame from a timelapse over #Europe, showing a transient luminous event in the upper atmosphere! We have a ????????-led facility monitoring these events thanks in part to @Astro_Andreas who took the first picture of them from space! ? https://t.co/tfFS3KqYmm #MissionAlpha pic.twitter.com/XqBdJ64pBq— Thomas Pesquet (@Thom_astro) October 7, 2021