Here's a slightly better list of the 50 Greatest Sci-Fi Movies Ever by TotalFilm:
50 Barbarella (Roger Vadim, 1968)
49 Primer (Shane Carruth, 2004)
48 Flash Gordon (Mike Hodges, 1980)
47 The Man Who Fell to Earth (Nicolas Roeg, 1976)
46 A.I.: Artificial Intelligence (Steven Spielberg, 2001)
45 Gojira (Ishiro Honda, 1954)
44 Serenity (Joss Whedon, 2005)
43 Forbidden Planet (Fred M. Wilcox, 1956)
42 THX 1138 (George Lucas, 1971)
41 Tron (Steven Lisberger, 1982)
40 Independence Day (Roland Emmerich, 1996)
39 Moon (Duncan Jones, 2009)
38 Total Recall (Paul Verhoeven1990)
37 The Day the Earth Stood Still (Robert Wise, 1951)
36 The Fly (David Cronenberg, 1986)
35 Akira (Katsuhiro Ohtomo, 1988)
34 Starship Troopers (Paul Verhoeven, 1997)
33 District 9 (Neill Blomkamp, 2009)
32 Solaris (Andrei Tarkovsky, 1972)
31 Dark Star (John Carpenter, 1974)
30 Brazil (Terry Gilliam, 1985)
29 Predator (John McTiernan, 1987)
28 Twelve Monkeys (Terry Gilliam, 1995)
27 Mad Max 2 (George Miller, 1981)
26 Metropolis (Fritz Lang, 1927)
25 A Clockwork Orange (Stanley Kubrick, 1971)
24 Minority Report (Steven Spielberg, 2002)
23 Robocop (Paul Verhoeven, 1987)
22 Eternal Sunshine of the Spotless Mind (Michel Gondry, 2004)
21 Invasion of the Body Snatchers (Don Siegel, 1956)
20 Wall-E (Andrew Stanton, 2008)
19 Jurassic Park (Steven Spielberg, 1993)
18 Planet of the Apes (Franklin J. Schaffner, 1968)
17 Star Trek (J.J. Abrams, 2009)
16 The Thing (John Carpenter, 1982)
15 Terminator 2: Judgment Day (James Cameron, 1991)
14 Close Encounters of the Third Kind (Steven Spielberg, 1977)
13 Donnie Darko (Richard Kelly, 2001)
12 Back to the Future (Robert Zemeckis, 1985)
11 Avatar (James Cameron, 2009)
10 The Terminator (James Cameron, 1984)
9 The Matrix (Wachowski Brothers, 1999)
8 Inception (Christopher Nolan, 2010)
7 Aliens (James Cameron, 1986)
6 E.T.: The Extra-Terrestrial (Steven Spielberg, 1982)
5 Star Wars (George Lucas, 1977)
4 Alien (Ridley Scott, 1979)
3 2001: A Space Odyssey (Stanley Kubrick, 1968)
2 The Empire Strikes Back (Irvin Kershner, 1980)
1 Blade Runner (Ridley Scott, 1982)