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A blue light over Europa has been captured from the International Space Station: this is the explanation of the strange phenomenon

ON October 8, astronaut Thomas Pesquet captured an amazing blue light on the European continent, somewhere southeast of Italy. From the International Space Station he was able to photograph the phenomenon and later published the image on Flickr. A blue stain that did not cause any damage and that went unnoticed by most despite its enormous size.

What is the explanation for this phenomenon? The astronaut himself leaves us a brief explanation at the bottom of the image. As defined, it is a “transient light event”, an electrical phenomenon equivalent to as if lightning struck the atmosphere upwards.

A rare electrical phenomenon that can be observed well from the Space Station

The phenomenon occurs in a “very rare” way, as described by the astronaut. Fortunately, the International Space Station is excellent for observing these types of events. Such is so the ISS has a laboratory, Columbus, dedicated to studying them.

“The fascinating thing about this lightning bolt is that only a few decades ago pilots had observed it anecdotally and scientists weren’t convinced they really existed“, says Pesquet.

Although this phenomenon is related to lightning, its operation is different. These “transient light events” often occur during thunderstorms, but higher than normal lightning.

Very occasionally, lightning can travel through the upper region of storm clouds before passing through the positive region. This causes the beam to strike upward, producing a blue flash and a blue glow of molecular nitrogen. It usually has a bluish tone, but depending on the height and inclination it can be seen in other tones, from orange to green.

‘Sprites’, “elfos” y “trolls”

The name given to these disturbances is curious. On one side are the ‘sprites’, large electrical discharges that occur above the storm cloud. On the other hand there are the “elves”, a popular name given to ELVES (‘Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources’). These are very faint bursts in the ionosphere, lasting a few milliseconds.

Finally we have the TROLLs (‘Transient Red Optical Luminous Lineaments’), a phenomenon that occurs after the strongest ‘sprites’ and produces a spot of red light. The fantastic names do not stop here, as there are different similar phenomena of brief light peaks with different colors. Green GHOSTs (‘Green emissions from excited Oxygen in Sprite Tops’) or “gnomes”, the most elusive for study and believed to produce white sparkles.

Red SpectrumRed Spectrum

First color image of a ‘sprite’ or red spectrum, in 1994. Taken from a NASA jet.

The study of these phenomena dates from 1988, when very brief and intense flashes of light began to be detected in the atmospheres of Jupiter and Saturn. That caused the attention of scientists who wanted to see if they were also possible to observe on Earth. A year later, in 1989, a storm cloud event was recorded in the China Sea. From then on they are periodically studied, being able to produce images as striking as the one captured by the astronaut Thomas Pesquet.

Vía | Science Alert