A while back, I wrote a blog post about Pandora, the gas giant moon that is the setting for Avatar, the visual masterpiece by James Cameron.
To celebrate the opening of Avatar 2: the way of water this week, I made a slideshow to give a little more astrophysical context to Pandora. And, like the movies, it’s all about the visuals — just click through the slides, like you’re sliding down a waterfall, with a gas giant hanging in the sky…
Additional Resources
- Real-life Sci-Fi Worlds: a series of blog posts at the intersection of science and science fiction
- Pandora (from the movie Avatar), the habitable moon of a gas giant planet (older post)
- The Dune planet Arrakis
- Kalgash, a planet in permanent daytime (from Isaac Asimov’s Nightfall).
- The hot Eyeball planet
- Black Holes, Stars, Earth and Mars: my astronomy poem book (just in case you need to buy a present for someone who loves both astronomy and poems!)
PLANETPLANET 
Neat summary! However, I think there is one small error. If the planet is around the size of Jupiter, and presumably the mass of Jupiter, then a 15-day orbit corresponds to an orbital radius of 1.75 x 10^9 m, or 1,750,000 km. At that distance from Polyphemus, and with a 29 degree orbital tilt to the plane of the orbit of Polyphemus, the configurations shown in the “Seasons” slide (i.e. the solstices) would not create eclipses for Pandora. It would experience the eclipses during some of the year around the equinoxes, but not every day.
Depending on the mass-radius relationship the Polyphemus follows, it seems like it would have to be well into the Neptunian regime in order for a 15-day orbit with a 29 degree obliquity to always experience eclipses.
Hi Josh — You are right, eclipses shouldn’t happen every time if Pandora’s orbit is aligned with Polyphemus’ equator. They should be seasonal, like you suggest. Thanks for catching that!