What is this rare blue light photographed by Thomas Pesquet from the ISS? – Numerama

Thomas Pesquet, on a mission aboard the International Space Station (ISS) until the end of October 2021, continues to photograph the Earth. In one of his last images, we can see a strange blue light phenomenon. Where is he from ?

” Photo taken from a timelapse of a flight over Europe. Luckily, she shows lightning and sprites in the upper atmosphere! ” Thus Thomas Pesquet presented one of his many photos taken since the International space station (ISS) on October 8, 2021, via Twitter. The French astronaut, on a mission in the station until the end of the month, currently controls the ISS, but that does not prevent him from continuing to strafe space.

In this image, we can admire part of the Earth plunged into the night: we can indeed distinguish a piece of the European continent, with the “boot” of Italy clearly visible. A small blue light appears just above the surface of the planet. What is it about ? As explain it Thomas Pesquet in a caption of the image, the snapshot shows ” lightning and sprites in the upper atmosphere! We now know that blue or giant sprites / elves / jets really exist and that they could have an influence on the climate.. “

These are transient light events during thunderstorms

Sometimes called sprites, elves, jets, angels or even leprechauns, these phenomena are in fact described by scientists as transient light events (TLE).

As detailed it the CNRS in 2020, ” these are flashes of light that occur during active thunderstorms, above our heads [ndlr : en l’occurrence, en dessous de celle de Thomas Pesquet], barely a few tens of kilometers above sea level “. They take place ” between cloud tops and 90 kilometers altitude “. These phenomena were discovered fairly recently, some thirty years ago, although their existence was presumed longer (since 1920). These TLEs can occur in all regions of the world, provided thunderstorms occur.

The CNRS distinguishes several ephemeral light phenomena:

• The elves, which a form of ” expanding light rings », Appear at an altitude of 90 kilometers. Their duration is very short: barely a millisecond (a thousandth of a second). A single thunderstorm can produce thousands of them for several hours.
• The sprites, with their ” complex filamentary structure », Take place between 40 and 90 kilometers above sea level. They can last up to 10 milliseconds.
• The blue jets, which are observable at the level of ” the upper part of thunderstorm clouds and spread up to 50 kilometers altitude “.
• Sometimes there are also giant jets, spreading up to 90 kilometers.

The brevity and rarity of these TLE ” the [rendent] difficult to photograph and study », Adds Thomas Pesquet. He specifies that the ISS is precisely equipped withan instrument (“Atmosphere-Space Interactions Monitor”, ASIM), devoted to the observation of these phenomena, outside the Colombus module. Since the station repeatedly flies over the Earth’s equator each day (ISS astronauts experience between 15 and 16 sunrises and sunsets every day), it is adapted to the study of TLE. It is at the level of the equator that we find the most thunderstorms, specifies the astronaut.

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