Ah, now here is what science-fiction was meant to be, a genre of ideas. The genre of writers like Arthur C. Clarke and Isaac Asimov, or in this case Polish author Stanislaw Lem and Russian film director Andrei Tarkovsky. I have not read Lem's famous 1961 novel Solaris, I've only seen two of the three movie adaptations (this one, and the recent one made by Steven Soderbergh and George Clooney) but apparently Lem was not happy about this version. He and Tarkovsky had communicated and worked together early on in Tarkovsky's adaptation, but ultimately they had different ideas. Lem thought the movie should simply be a direct adaptation of what was in the book, whereas Tarkovsky felt that the movie should be based on the book, but different enough to stand up on its own as an independant work of art.
The movie begins as psychologist Kris Kelvin (Donatas Banionis) is readying to leave Earth for the spacestation orbiting Solaris. He's been called upon to make a judgment regarding the mental state of the crew of the station, and whether or not the station should even continue. Humans have been studying the planet for years, with no true findings to present. When Kelvin arrives, he is not greeted by anyone, and the station seems to be in a rapidly declining state of neglect. He finds that his friend Dr. Gibarian has committed suicide in his room, but has left Kelvin a cryptic video message in which he insists that he's not insane. He is given a vague warning by Dr. Snaut, one of the two remaining crew members, that should he run into anything strange, he should stay calm and not overreact. Kelvin doesn't understand the message until that night, when he wakes from sleeping to discover a woman in his room, despite his barricaded door. The woman is his wife, Hari (played by the mysteriously attractive Natalya Bondarchuk). He's taken aback by her appearance, because Hari had comitted suicide many years before. The next morning, Dr. Snaut is more forthcoming with Kelvin, now that he has been visited by a "Guest". Snaut explains that all the crew members were visited by Guests after they tried to x-ray the surface of Solaris. They theorize that Solaris may not be just a planet, but some sort of sentient being beyond their comprehension. The Guests seem to be manifestations of people the crew members want to see, created by Solaris.
The movie goes on from there to explore themes of love, what it means to be human, and what we're really hoping to find in space travel and research. Tarkovsky has made a movie that is certainly not for everyone, many people complain that Solaris is boring and slow, but I never thought so. Early on, while still on Earth, we get an absurdly long scene of a man driving through the city. I'm sure some people don't think this had a point, but I think Tarkovsky was trying to evoke the extended time it still takes to move around Earth, there are no teleporters or easy fixes just because this is science-fiction. I also think that Tarkovsky uses long takes, and a "slow" atmosphere to get the rhythms of daily life. Life isn't the roller coaster ride we see in many movies, it's often slow and quiet, and I think the people and (even outlandish happenings) seem more real because Tarkovsky has set us up into a realistic feeling world. Steven Soderbergh tried to do this in his adaptation with George Clooney, and the main complaint about his version was that it was slow. It almost has ADD compared to Tarkovsky's.
Movies like Solaris are what sci-fi movies are supposed to be. We get fed a lot of the same sci-fi over and over again, but sometimes a movie like 2001: A Space Odyssey, Children of Men, or Dark City comes along and reminds us that ideas are what makes science-fiction so great. Sci-fi can tackle any subject in any way, because it is not tied down to anything, it can create its own world. On the other end of the spectrum, sci-fi can get too bogged down in ideas, and forget to create real people with whom the audience can identify. Solaris comes along and gives us what is often missing from sci-fi, humanity and ideas.