Hi, I have a few questions about telescopes; (But a quick disclaimer: I know almost nothing about telescopes or astronomy) My uncle lent me his Celestron C90 telescope (he said it would be a good thing to start with) and I tried it out just now. I saw the moon with it, and it was incredible; one of the most beautiful things I've ever seen. The weird thing was, when I tried to look at stars, I would see a pretty blurry ball of light (which is what I expected), but in the middle there was a black ball. Is that a problem with the telescope, or the eyepiece, or does that always happen? To learn to see more things, I got an app for my phone called Night Sky that I hope will help me know what I'm looking at. Is that enough or should I also get a book? Also, when should I move on to a better scope? (And what would that scope be?) What resources could I use to learn more about telescopes and astronomy? Is the scope I'm using now good to start with? PS. I'm planning to take a summer class in astronomy (as well as physics, of course :D) in a university here in Chile, so I hope to learn more there.