Science fiction has always been my favorite specific genre (well, sort of specific; of course there are any number of sub-genres of science fiction). But SF is itself part of a group of genres collectively called "genre," so you should also check out other movie genres, such as:
action/adventure, anime, B-movies, comic book adaptations, dystopian, fantasy, giant monsters, sci-fi horror, and supernatural
See also SF books, SF TV, and SF webseries
I also want to note that, while I'm using a background of stars for my science fiction reviews, certainly not all sci-fi involves space. Basically it's just anything that involves science that is beyond what we currently have in reality. Which is a pretty broad spectrum. So I may include lots of different types of movies here, though... yes, most of them will probably involve space travel and/or aliens. I dunno what else to say, really. Except that some sci-fi is kind of mindless fluff, involving explosions and stuff, while other sci-fi is more intellectual than anything else... and some stuff falls somewhere in between. Of course, I could get all philosophical about it and say that science fiction is really about ideas, thinking about the unknown, and so forth, which is the kind of thing people often associate with star-gazing. Ta-da.