![[Image: Gm1gxQYXAAAfPaD?format=jpg&name=medium]](https://pbs.twimg.com/media/Gm1gxQYXAAAfPaD?format=jpg&name=medium)
There's actually a very simple explanation of what it is. It's the second stage of today's successful NROL-69 mission. This was a SpaceX Falcon9 launch for the US National Reconnaissance Office. (One or probably more spy satellites.) The rocket stage is venting propellant in space as it rotates. While it's dark down below (in the Earth's shadow) the vapor plumes in space are illuminated by the Sun.
Video of it passing over Croatia
Reminds me of a depiction of an alien planet sky. Maybe there are planets that are close to a real spiral galaxy in their neighbourhood and the view is commonplace.
I wonder how much of that propellant it would take to light up a good chunk of the night sky. Maybe they could use it near the poles where there isn’t much light for a significant portion of the year.
I'm surprised Musk hasn't said "Mission Failure... It was suppose to be an X" (Afterall it would be possible to create a logotype in such a manner )