A mysterious lightning sprite in the sky ! What is it ?

What you see here is a red sprite, captured by an astronaut aboard the International Space Station, which happened to be passing over Myanmar during a large thunderstorm.

Sprites — named after Puck, a nature sprite in English folklore — are huge electrical discharges that occur in the mesosphere (50-100km above Earth), which are triggered by positive lightning strikes on the ground below.

Beyond that, we don’t know a whole lot about sprites. Because they’re so high up in the sky, often obscured by huge clouds, and only exist for a few milliseconds, the existence of sprites was only confirmed in 1989 when the University of Minnesota accidentally caught one on tape. Since then, they’ve been captured on film and tape hundreds of times — but their properties and the mechanism that creates them is still a big mystery. My educated guess would be that lightning strikes also send some energy up into the mesosphere, where the electrons collide with other molecules (oxygen, when excited, emits a red glow).

The photo of the sprite is actually a still frame from a time-lapse sequence shot by Expedition 31 aboard the ISS. The sprite appears around the 7-second mark, in the top right corner of the frame.