A Blue Luminous Event

On October 8, French astronaut Thomas Pesquet captured something strikingly rare from on board the International Space Station (ISS).

The photo – which is a single frame taken from a longer timelapse – might look like it shows a cobalt bomb exploding over Europe, but this scary-looking blue light didn't do any damage. In fact, most people would never have noticed it happening.

Instead, the frame shows something far less ominous called a 'transient luminous event' – a lightning-like phenomenon striking upwards in the upper atmosphere.

Also known as upper-atmospheric lightning, transient luminous events are a bunch of related phenomena which occur during thunderstorms, but significantly above where normal lightning would appear. While related to lightning, they work a little bit differently.

There are 'blue jets', which happen lower down in the stratosphere, triggered by lightning. If the lightning propagates through the negatively charged (top) region of the thunderstorm clouds before it gets through the positive region below, the lightning ends up striking upwards, igniting a blue glow from molecular nitrogen.

Then there are red SPRITES (Stratospheric/mesospheric Perturbations Resulting from Intense Thunderstorm Electrification) – electrical discharges that often glow red, occurring high above a thunderstorm cell, triggered by disturbances from the lightning below – and slightly dimmer red ELVES (Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources) in the ionosphere.

Sticking with the theme, there are also TROLLs (Transient Red Optical Luminous Lineaments) which occur after strong SPRITES, as well as Pixies and GHOSTS. We're sure the scientists had lots of fun naming all of these phenomena.   READ MORE...