Space.com (December 27, 2009)
"The new science fiction blockbuster 'Avatar' is set on habitable and inhabited moon Pandora, which orbits the fictional gas giant Polyphemus in the real Alpha Centauri system.
"Although life-bearing moons like Pandora or the Star Wars forest moon of Endor are staples of science fiction, astronomers have yet to discover any moons beyond our solar system. However, they could be science fact, and researchers might soon not only be able to spot them, but also scan their atmospheres for key signs of life as we know it, such as oxygen and water.
" 'If Pandora existed, we potentially could detect it and study its atmosphere in the next decade,' said astrophysicist Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass...."
That word, "potentially," covers a lot of ground. According to the article, the next-generation James Webb Space Telescope's system could analyze a moon's atmosphere - if the moon and its planet passed between their star and Earth at intervals. My guess is that the odds aren't particularly good for the host planet's orbit to line up like that.
On the other hand, with hundreds of known planets orbiting other tars - and more being found on a fairly regular basis - it's not at all impossible that we'd find a transiting planet-moon system orbiting another star.
The Space.com article does a pretty good job of discussing what it would take for the moon of a gas giant to be habitable, based on what we know about radiation belts and tidal forces in the neighborhood of worlds like Jupiter Saturn.
More about the setting of Avatar:
- "The Real Science of 'Avatar' "
Space.com (December 21, 2009)
- "Beautiful Space Princesses, Almost Certainly Not: Flying Whales, Maybe"
Drifting at the Edge of Time and Space (December 8, 2009)
- "Really Old Dust Grains, a Galactic Collision, and a Lively Interest in God's Creation"
A Catholic Citizen in America (August 10, 2009)