I wouldn't consider myself an Astronomer yet, but I'm on the way to getting there (I just started my master’s thesis).
Indeed, there doesn't seem to be a lot of Astronomy-related discussion on the Fediverse, but that might be because it is a niche in a niche. And at least in my experience Astronomers are on average more interested in Free Software than other people, so there might be a chance.
Mastodon ist ein soziales Netzwerk. Es basiert auf offenen Web-Protokollen und freier, quelloffener Software. Es ist dezentral (so wie E-Mail!).