My top two favorite resources for the scope of any Stack Exchange site are, in order, the tour and the help center. The former takes maybe a minute or two to read and should clear up some basic questions; the latter is useful for more specific concerns about scope and allows us to be more explicit about certain unique rules and guidelines.
The help center is in decent shape; moderators can edit certain pages, and, in general, this can/should be done early on, and revised later. The Astronomy What topics can I ask about here? page (moderator-editable) is one of the better ones I've seen, and I think it outlines the scope nicely. The Astronomy What types of questions should I avoid asking? page is substantially vaguer, but it's not moderator-editable and is the same for each site; at any rate, I think it's intended to be less important than the other page.
The tour on Astronomy could, I think, be better. It's the first place I visit when joining any Stack Exchange site, because it's concise. However, it's currently using the default text in most areas, I believe, which isn't good. Some parts can be edited, including the sections under the headings
- Welcome to Astronomy Stack Exchange
- Ask questions, get answers, no distractions
- Get answers to practical, detailed questions
The second one has been changed from the default to use a modified version of What is the name of our Solar System?; whether another question should be chosen is maybe something we should think about (criteria are given here). The third one is what I think needs to be changed; a good example is the version on Physics Stack Exchange. It has
- Examples of things to ask and not ask about
- Links to meta questions on topics that need more detail
- A couple of the default bullet points
I think we need to edit this section, as it's easy to point people to and easy to read; I'd also guess that many more people are willing to look there than in the help center, even if it's just to get the informed badge.
Here's my proposed text (it's just an example; we can change it):
Ask about . . .
- Experimental and theoretical problems in astronomy, astrophysics, cosmology, and planetary science
- Astronomical equipment, both professional and amateur
- The use of space probes, telescopes, and rovers for astronomical purposes
- Certain resource requests
Don't ask about . . .
Obviously, some of this needs to be a bit clearer, but you get the idea.
Now, we could instead just add in a version of the text from the What topics can I ask about here? page in the help center, as Space Exploration has done, but I feel like that would be too long and bulky - not concise enough for a good tour.