I can’t see anything
It’s not cloudy and you’ve ensured that your telescope’s objective lens and finder scope caps are off, but you’re still struggling to see your chosen target. If you’re having difficulty seeing anything through your telescope, then one or more of the following could be to blame.
Option 1 Your telescope might not be collimated properly
When a telescope is collimated properly, all of its mirrors or lenses are aligned. When they aren’t lined up, then light from the object you’re looking at can’t be reflected or refracted in such a way that you can see the object through your eyepiece.
Solution
Schmidt-Cassegrain telescopes and reflectors can usually be collimated with ease, at least once you know what you’re doing. However, unless you’re an optical expert, we wouldn’t advise trying to align the lenses in a refractor. Remember, if you’re unsure of how to collimate your instrument, it’s best to err on the side of caution and take it to an expert who knows how.
Option 2 You might not be dark adapted
While it’s true that you can see some brighter targets as soon as you head outside – and even under moderately light polluted skies – it’s not true for the fainter stars and planets, even through a telescope.
Solution
This is a rookie mistake to make, but fortunately one that’s easily corrected with minimal experience. You should wait for your eyes to adapt to the dark before trying to view the night sky. This usually takes around 20 minutes. If you need to use a torch, ensure that it emits red light rather than white.
Option 3 You might not be aiming at anything
It seems like a silly mistake to make, but you might find that your telescope isn’t pointing at anything in particular other than a patch of dark sky, devoid of any bright objects.
Solution
Simply make sure you’re pointing your telescope at a bright target, at the very least to check if there isn’t something more serious afoot. A good example of one is the Moon – if it’s out on the night you have chosen to do your observations and viewing.