I remember taking a physics class in high school, and an astronomy class in college, and being somewhat disappointed that stuff that like travelling at the speed of light or visiting other star systems will probably never happen for real (unless someone comes up with some really fantastic ideas that enable us to really travel at near the speed of light and what not without requiring too much mass to make it feasible).
That doesn't mean that you won't learn some interesting stuff though (I like the twin paradox that talks about I think einstein's theory of relativity, where if you travel at near the speed of light, time slows down for you, so if a twin travels for a year at like 90% of the spd of light, when he comes back, his twin on earth will have aged like 40 years while the twin on the ship will only be a year older).
You'll probably also learn of Newton's three laws as well. For instance, an object in motion tends to stay in motion unless acted on by a force. So for instance, say during WW2, when planes were dogfighting over the Pacific Ocean, bullets that missed would eventually get slowed down by friction from the air and gravity acting upon it, so it would fall harmlessly into the water for the most part. In outer space, there would be no air, and if you're not near a source of gravity, such as a planet, that same bullet flying from a gun in space would continue to fly through space at the same speed until it either hits something, or gravity pulls it down.
It certainly does help to make your story more "convincing", but for me, while I do know some of this stuff, I think that it'll be too much of a hindrance, so I just chuck a lot of it out the window for the sake of telling a good story. For instance, again, FTL (faster than light, or "hyperspace" as it's popularly known in many sci-fi books) travel will probably never happen (and you'll probably learn this in your physics class if you ask your professor), but man, if the book is good, I really don't care that a spaceship can defy some laws of physics hehe. You'll probably have critics no matter what you write about, but again, if your story is good enough, most people won't care about it.
That's my advice. You can take it for what you think it's worth. I'm no expert on this stuff (I suck at math hehe), but I don't think anything I've told you here is entirely false or inaccurate either.