If you haven’t checked out @FediTips , it’s a great place to start.
There’s no algorithm to feed you here, so you need to put in a bit of effort at the start to kick things off.
As others have mentioned, you can search on people and their main hashtags. Following hashtags and people related to your interests is the best way to start filling your feed with things of interest to you.
Using hashtags enthusiastically will help people find you.
A couple of other cultural points. Please use Alt-text on every image you post if possible. This is a platform with a high proportion of users for whom accessibility matters, and there is solidarity on this point. Many users won’t interact with you or boost posts with images without Alt-text. If you’re not yet ready to describe your images, there is a hashtag Alt4Me, that invites others to describe your images.
Last, you’ve chosen a large instance that brings with it some of the challenges of a large platform like the one you have just fled. As you go forward, you might wish to migrate to another instance that aligns more closely with your personal stance on moderation.
Hey Chris, welcome! 👋
There are lots of ways to discover accounts to follow on here: https://fedi.tips/how-do-i-find-accounts-to-follow-on-mastodon-and-the-fediverse-how-do-i-find-my-friends/
There are some astrophotographers listed here too: https://fedi.directory/tag/astrophotography/
(If you want to follow from the directory, copy-paste an address into your search box on Mastodon to bring up their account.)