ELVES, the light phenomenon first hunted by a satellite 400 km high

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ELVES, the light phenomenon first hunted by a satellite…

Looking at our skies not from the ground but from above is very useful and sometimes provides us with beautiful surprises. This was the case with the latest photograph taken by the storm chaser device installed on the International Space Station (ISS), which studies how, where and why atmospheric phenomena take place. Its powerful sensors and photometers record a huge amount of data. Thanks to this satellite, orbiting at an altitude of 400 kilometres, ELVES have been spotted from above for the first time.

But what are ELVES? Naturally, we’re not talking about forest gnomes with pointy ears. In meteorology, ELVES (“Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources”) are the highest of all known luminous events. ELVES appear and disappear in the blink of an eye, just like lightning. But they are a very special kind of lightning: a series of concentric rings expanding hundreds of kilometres across, formed by electrons that collide with and exciting nitrogen molecules. They’re just like gorgeous jellyfish-shaped bolts travelling across the skies in just centiseconds.

One of them was registered with unprecedented accuracy by the ASIM (Atmosphere-Space Interactions Monitor), installed last April outside the EEI’s Columbus laboratory. The discharge occurred during a thunderstorm off Sumatra island, Indonesia, and was observed when it reached the upper layers of the atmosphere, at which time it became an ELVES. “We collected 100,000 measurements per second of this amazing force of nature”, said Torsten Neubert, chief of the scientific team at the Technical University of Denmark. “This fantastic achievement shows how powerful our photometers are”.