Last week, an astronaut aboard the International Space Station captured a lightning strike over Europe. But unlike most lightning, this electrical outburst was not a bunch of spiky tendrils but rather a big blue bubble over the continent.
The “transient luminous event,” as such upper atmospheric lightning is known, was spotted in a timelapse taken by French astronaut Thomas Pesquet. This sort of lightning looks different from the flashes that occur in and below storm clouds and tends to be much larger.
There are sprites, which are vertical, supertall bright flashes of red or bluish-green light; jets, which tend to be blue and occur in the stratosphere; and elves, which are very high-altitude electromagnetic pulses. There are also trolls, which are jet-like, and other magically named luminous forms of lightning that happen above the clouds.
The colours of the various phenomena are shaped by the atmosphere; on Earth, nitrogen makes sprites appear red, but on Jupiter, a hydrogen-rich atmosphere would make sprites blue.
Since 2018, the ASIM experiment aboard the ISS has observed these forms of giant lightning. It is the successor to the earlier THOR experiment proposed by Danish astronaut Andreas Mogensen, who caught blue jets and red sprites on video over the Bay of Bengal in 2015.
These forms of lightning are extraordinarily brief, so researchers had to go back through Mogensen’s footage frame-by-frame to pick out specific phenomena. Similarly, Pesquet’s photo of the recent transient luminous event was extracted from a longer timelapse of the night sky.
In a caption for the new photo posted online, Pesquet noted that the ISS is well-positioned to photograph such phenomena, as it flies over the equator, where more thunderstorms occur. This particular event popped up somewhere southeast of Italy, as the picture shows.
“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,” he wrote. “Fast forward a few years and we can confirm elves, and sprites are very real and could be influencing our climate too!”
More observations like this one are sure to come and reveal more about these brilliant natural phenomena, so dazzling that they required supernatural names.
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