Astronomy and Geology
In the film, Pandora is depicted as being located in the Alpha Centauri A system approximately 4.37 light-years (276,000 AU) away from Earth. It is one of the many natural satellites orbiting the gas giant Polyphemus, named for the Polyphemus of Greek mythology. Pandora's atmosphere is a mix of nitrogen, oxygen, carbon dioxide, xenon, ammonia, methane, and hydrogen sulfide. Humans cannot breathe this, so they wear Exo-Packs when outside their buildings or vehicles.
Leri Greer, a designer at Weta Workshop, explained the unusual day/night cycle experienced by the Na'vi, who inhabit a moon orbiting a planet, that in turn orbits around a star.
I actually wrote about how it causes a particular sky coloration across the visible spectrum at moments of pure dusk. And the Na'vi, depending on what elevation they live at (sea level versus higher altitudes), perceive a distinct color in narrow band at the horizon at that moment. They identify themselves, and signify in their markings, with this color. Which helps other Na'vi quickly discern at a distance what/where they are from, or what they are likely to be like (fishermen, high plains, skyriders, etc.). That pure dusk "color," combined with their other predominant color markings lets you also know how they relate to Eywa as a "religion" versus Eywa as a physical reality. And during ceremonial gatherings you can "read" a Na'vi by how they mark themselves with dyes, muds, and paints. And the environment and day/night cycle is directly responsible for the development of this social expression behavior. Again, this was an internal idea to help us design things at Weta Workshop, it's hard to say how much filtered upward to the larger production.
Pandora has lush, tropical rainforests that cover much of its continents. Pandora also possesses a lesser gravitational force than Earth does. The geology of Pandora is strongly affected by the presence of unobtanium, a mineral whose superconductive properties allow it to float in magnetic fields. This property makes it highly valued by humans, who mine it for transport back to Earth. Pandora's levitating Hallelujah Mountains contain significant quantities of unobtanium, which allows them to ride the strong magnetic fields in their region. Cameron hopes to explore the other moons in future sequels, books, and spin-offs.
