One satellite, one rocket stage. "One (Cosmos 2004) is an old Russian communication/navigation satellite from the 1980s, and the other (CZ-4C R/B) is the upper stage of a Chinese Long March rocket that launched in 2009. Both of them are inactive and have been for a long time."
Sounds more like the trailer of a romantic comedy than a terrifying space accident.
Mastodon is a server for a federated social network: everyone can run a server if they want to, including me. So this is a Mastodon server for me (Vierkantor) and my friends.