I have this little project of my own to determine to how extent is Avatar's story-line scientifically possible. Pandora, where the story-line of Avatar takes place is depicted as a moon orbiting around the gas giant Polyphemus that orbits around the star Alpha Centauri A.
In this project, I have to find a large amount of facts unspecified/not explicitly specified in the film. Among these many facts, one would be the size of the orbit of Polyphemus, the gas giant which Pandora orbits around.
We currently know that Alpha Centauri A is a star slightly larger than our Sun, and it's one of the stars in a binary system. The size of the orbit of Polyphemus will tell us how far Pandora is from its host star, and thus how much radiation it gets. Then we can determine whether or not Pandora can support life.
So, how far is Pandora (and Polyphemus) from its host star, Alpha Centauri A?
This will be the start of a series of questions (a multiple question, now deleted) I have.