Redditors recently got together on r/movies, the largest film subreddit, to discuss which sci-fi movies stick with the viewer the most. They mean the ones that touch on fascinating ideas and include a lot of food for thought.

Many sci-fi films are fun in the moment but don't have much substance, or they simply rehash old ideas. However, every now and then, one comes along that breaks new ground. These projects linger in the mind long after the credits have rolled.

10 'Contact' (1997)

Contact’  (1)

Contact delves into humanity's insatiable thirst for knowledge – and its occasionally grim consequences. It's directed by Robert Zemeckis from a novel by scientist Carl Sagan and stars Jodie Foster as Dr. Ellie Arroway, a scientist who discovers proof of a faraway alien intelligence.

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"Contact was already one of my favorites. Rewatched it the other day when I noticed it’s on HBO Max and loved it even more. It holds up so well. One of the most underrated movies of all time," said user LETS_MAKE_IT_AWKWARD.

9 'Forbidden Planet' (1956)

Robot and crew on a planet

This quirky classic movie centers on a group of space explorers who discover ruins left behind by a long-extinct advanced race. Forbidden Planet was a trailblazer in the genre, particularly with its innovative special effects, including the iconic robot Robby. He represented a major step forward for robots in film, in that he's a supporting character in his own right.

"If you want to go old-school cool: Forbidden Planet. Bonus: Leslie Nielsen as a leading man," said jeffsb. "I love this movie and highly recommend it, but like any old movie you need to adjust your brain a little to get the most out of it," said TheGRS.

8 'Gattaca' (1997)

Ethan Hawke in Gattaca
Image via Sony Pictures Motion Picture Group

Ethan Hawke stars in this sci-fi set in a dystopian future where genetic engineering has created a society divided between the genetically superior and the natural "in-valids" who are deemed inferior. It's thought-provoking, especially because a lot of the technology already exists, albeit in a much simpler form.

"Gattaca is one of my absolute favorite movies of all time – top 10 at the very least. Fun fact: Back in 2011, NASA rated Gattaca as the most plausible sci-fi movie of all time," said Sentrion.

7 'Edge of Tomorrow' (2014)

Emily Blunt and Tom Cruise looking to the distance in a poster for Edge of Tomorrow.

Major William Cage (Tom Cruise) finds himself caught in a time loop, reliving the same brutal battle against an alien invasion again and again. With each iteration, Cage becomes more skilled and determined to break the cycle and save humanity. Edge of Tomorrow is one of the most purely fun sci-fi movies in years, but it's also jam-packed with intriguing ideas.

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"Edge of Tomorrow is an absolute must," said user furianeh. "Edge of Tomorrow is sooo good," agreed superjenious. "It's really a 3 way split for best time loop between this, Palm Springs, and Groundhog Day."

6 'Palm Springs' (2020)

A still from Palm Springs” (2020)

This delightful sci-fi rom-com centers on Nyles (Andy Samberg) and Sarah (Cristin Milioti) who find themselves trapped in an infinite time loop during a wedding in Palm Springs. As they navigate the surreal (and often hilarious) repetition of the same day, their initial antagonism evolves into a deep connection as they contemplate the meaning of life, love, and personal growth.

"Palm Springs was way better than I expected," said Evakron. "Watched it because my girlfriend is an Andy Samberg fan, expected some cringe and an inconsequential story. What I got was an easily digestible philosophical exploration of humanity's relationship with time, purpose, inevitability, and escapism."

5 'Annihilation' (2018)

A group of female soldiers armed with guns standing in line in Annihilation.
Image via Paramount Pictures 

Screenwriter-turned-director Alex Garland had proven his sci-fi chops with his directorial debut Ex Machina, but he took things to a whole other level with his sophomore project Annihilation. It follows a group of scientists who enter "The Shimmer," an eerie phenomenon that defies the laws of nature. There, they discover far more than they bargained for.

"I watched Annihilation recently. That third act really viscerally terrified me in a way that nothing else has," said one Redditor. "This movie got under my skin unlike any other movie," agreed thespianomaly.

4 'The Fountain' (2006)

The tree of life in The Fountain
Image via Warner Bros. Pictures

Darren Aronofsky is famous for trippy movies like Mother!, but his weirdest film is arguably The Fountain, starring Hugh Jackman and Rachel Weisz. It weaves together three interconnected narratives that span different time periods and explore the quest for eternal life.

"Some similar themes as Interstellar (love/time) plus great visuals and a deep and beautiful story. My personal favorite movie," said ibenjamind. "The Fountain is one of my favorite movies as well. I wish people appreciated this movie more since the themes of love and loss are so strong in this movie and told through an amazing story. Rachel Weisz and Hugh Jackman are a great pairing for this," said the user qaa541.

3 'Sphere' (1998)

sphere 1998 dustin hoffman0

Dustin Hoffman stars in this film about a team of scientists who discover a mysterious spacecraft at the bottom of the ocean. As they investigate the wreckage, they encounter a powerful force that tests their perception and challenges their understanding of reality.

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Hoffman is joined by a terrific ensemble cast including Sharon Stone, Samuel L. Jackson, and Liev Schrieber. The Redditor No-year9730 called it "space but underwater." "Sphere absolutely terrified me as a kid," said the user jimmy-c-b.

2 'Event Horizon' (1997)

event horizon

A rescue crew set out on a mission to investigate the mysterious reappearance of the experimental spacecraft, Event Horizon, which vanished years earlier. However, they soon learn that the forces aboard the vessel are not of this world. Event Horizon was a box office bomb on release but has since garnered a cult following.

"[Event Horizon] plays out like a haunted house movie in space," said CuddlyIronBoot. "It's also the rare horror movie where the characters are all competent and make logical decisions. I absolutely love Event Horizon. Fun fact: if you have played Dead Space, Isaac's helmet was based on the front of the ship."

1 'Moon' (2009)

Moon - 2009
Image via Sony Pictures Classics

Sam Rockwell carries Moon, an introspective sci-fi film that's essentially a one-man show. Rockwell plays Sam Bell, an employee on a lunar base who is nearing the end of his three-year solitary stint. However, he starts questioning everything when he encounters a clone of himself on the base.

"Moon is an amazing film. Sam Rockwell is a superb actor and it's really well shot," said UnfinishedThings. The Redditor who started the thread watched it and was blown away. "What a ride! Definitely got what I was asking for. I’ll be thinking about this movie for weeks! Great acting. No idea how I would handle that situation if I was in it," said LoveSeemsDoomed.

NEXT: The Best Sci-Fi Movies of All Time, Ranked