EDIT - The answer is that it is Falcon 9. And the spiral is excess fuel released from the rocket.
#astro #question This object was just passing over Brno (21:00-21:03 CET) from NWW to SEE. It started as a small butterfly from light - I thought about some kind of halo around a bright star. But it was moving in satellite speed, and the halo was rotating and growing. Photos are bad because it is from phone.