From the director who brought us Trainspotting, this is an excellent sci-fi that combines the thoughtfulness of 2001 with some real sounding dialogue like we saw in Alien, all to the tune of an original premise. The concept is that the earth is frozen in the future, and a small group of scientists and astronauts are launched on a mission to re-ignite the sun, without having any idea what happened to the first team after they disappeared.
There are very human moments (a character walks into a room, stares at a second character until the second characters says "Is that your apology?" The first one replies "Yes," and they turn away from each other) and with all humanity hanging in the balance one simple decision that doesn't seem unreasonable begins a chain of events that makes the mission an increasingly desperate one. The end is a little surreal, and not paying close attention can allow you to miss some important information, but it's nothing that isn't in keeping with the tone and thoughtfulness of the film.
Like Blade Runner, this is one of those films that was fairly misunderstood on release (don't expect a disaster movie, an action film or aliens, this is somewhere between a drama and an art film), but I believe it will eventually gather a following and be considered a classic.