Carole McDonnell passed me the Best SF Movie scene meme...
There are some famous, favorite scenes already mentioned by Carole, Stacia, and others, great scenes from Gattaca, Blade Runner, Dune, Logan's Run.
So, I dug around for something not yet mentioned:
The Fifth Element, the scene in which Zorg (Gary Oldman) explains how the universe works, how things are to the priest Cornelius, and ends up having to be saved by his captive.
Here's the scene on YouTube:
It would be difficult to tell you why I love The Fifth Element. I know a lot of people hate it, put it down as one of the worst SF movies, but there's something about the mix of Gary Oldman, high-speed rocket taxi chases, operatic cut scenes with murder, countdown timers on explosives, good versus evil, the end of the world, and futuristic kitsch that works for me.