Tough question. Couldn't tell without examples of your writing. I'd say just go for it and let what comes out come out.
if you can't, you can't<br />
I am not trying to undermine YOU, but writing a story (even a fantasy, where your imagination can be a plot-saving instrument) is very difficult<br />
If you have to ask a question of this nature then my opinion is that you're going to find it hard<br />
but I hope this helps (maybe): start writing a 'serious' story - and you will find the fanatsy somehow just marerialises. If you put sad, ancient elves in consciously then of course it will be cliched high fantasy<br />
Write a true but stranger than fiction type of story.
you may not want to write fantasy.
you can use the astronomy as a fantasy element ....
So it won't be "A Dark and Stormy Night" for instance.