It was 49 years ago this month that a movie came out and changed the course of sci-fi cinema.

That movie, of course, was 2001: A Space Odyssey. Released in April 1968, the film was produced and directed by Stanley Kubrick, and written by Kubrick and legendary science fiction writer Arthur C. Clarke. Although there had been exceptional films released in the genre before it (including gems like Forbidden Planet, The Day the Earth Stood Still, The Incredible Shrinking Man and Quatermass and the Pit, to name a few), 2001 was a quantum leap forward both in filmmaking and the portrayal of subjects like spaceflight and human evolution.

While there have been a lot of good and even great sci-fi films made since the genre was born -- heck, it's almost as old as cinema itself if you consider 1902's A Trip to the Moon as "film zero" -- there aren't many that can be said to capture the sweep, majesty and cosmic awe of the genre at its finest. 2001 did that in one evolutionary leap, creating a gold standard that decades' worth of movies since have aspired to -- and few have equaled.

Here are 10 reasons why 2001 remains the greatest sci-fi movie of all time: