TLDW: Russia is jamming GPS and GNSS over Europe, purposefully, using a constellation of military satellites.

Theory is that Russia is constantly practicing to totally disrupt GPS and GNSS (and the Chinese system) across all of Europe.

Anyone have a good source to read up on the current state of the art for daytime celestial navigation? Maybe there isn't too much in the public domain, because things like GPS work so well. But I'd guess that since you can't easily artificially jam celestial navigation there would be military research on this. But I suppose clouds also limit the practicality as well.

https://www.scientificamerican.com/article/how-to-see-stars-...