I don’t see it as “trite” at all, unless the big emphasis is on the “starting” and not on the club and what you do and what it says about you. Think of it this way: You want the Activities List to show who you are as a person. You’re into stargazing and astronomy? Cool! If it’s not necessarily related to your academics, I’d say that’s even better. The more stuff that isn’t the usual Athletics, Band, “I Live And Breathe Academics,” and Selfless Service to Others, the more you’ll stand out.
I’m not saying those other things aren’t good if they’re genuine interests – in which case you’ve probably got a kind of “theme” developing among your activities that shows growing focus in certain areas – but unusual things like “started an astronomy club” is actually pretty neat, particularly if you end up doing things like, I dunno, getting up at 4 am to see meteor showers.
My S at first didn’t want to include the totally hobby-related club he started (and spent a ton of time on – too much, frankly, LOL) on his Activities List for the same reason – he also thought it could seem trite, or not serious, or something like that. But honest to gosh, when the list was complete, it was so cool to see that funky hobby popping up among everything else, because it really helped to paint a picture of him as a full person. His ECs ended up looking great, not because of “started this or that” or “won this or that” (which he didn’t have much of), but because it’s just a clear picture of him as a person. And honestly I think that’s what you want.
Starting a club isn’t a big deal in itself. But what you do with it, and how it’ll end up showing who you are and differentiating you from the crowd (as a person, not as a “leader” – e.g., a community service twist would probably spin it towards trite because who’s going to believe you do stargazing to help the community?), is what I think would make it “trite” or “not trite.”
Oh, and either way, it’s not going to be a negative. C’mon, who thinks that way? (“Look at this kid! He started an astronomy club! What does he think that is, some big deal? That is SO bad. Let’s not let him come to our school.”) If you want to do it, go for it!