The scale was just right: two humans against the awe and peril of the cosmos. The fact that it was two rather than more made all the difference, and gave us a chance to get into the thinking especially of Ryan Stone, the main character, well played by Sandra Bullock. George Clooney's Lt. Matt Kowalski was also perfect in the crucial supporting role.
We're tragically accustomed to catastrophes in space travel, due to the Challenger and the Columbia space shuttle disasters. But these actually were disasters of space travel not far off the Earth, and the only disaster the took place out in space was actually the close call, not disaster, of Apollo 13, made into a superb, realistic movie by Ron Howard back in 1995.
Gravity, a totally fictional story, is closer to Apollo 13 in taking place well off Earth, but with tragic circumstances for all but one of the crew. All the icons of near-Earth orbit, old and new, are brought into play in this riveting story, including the US Space Shuttle, the Hubble telescope, the International Space Station, the Russian Soyez, and the Chinese Tiangong 1 space station, just launched in 2011. The interplay of these major players in near space - each has a significant role in the story - is one of the best parts of the movie.
Stone's struggle to survive and get back to Earth is also one of the more satisfyingly heroic stories to appear on the screen in some time. This is due, in large part, to the sheer complex simplicity of the contest of one woman against the universe. Although I guessed that Kowalski's return was a dream, his role in the story, including his sacrifice to give Stone a fighting chance, was also one fine piece of moving movie making.
Outer space in the movies has all too often been given over to military conflicts and vast battles. These can be excellent, but also make a movie on the human scale of Gravity all the more inspiring.