Alien Worlds in SciFi Movies

Avatar’s Pandora is Beautiful

But Too Good to be True

So, we went to see Avatar last night — in glorious 3D at the IMAX theater.  It’s a beautifully rendered film and I was reminded of scenes from the game Uru (which, nearly a decade ago had similar lovely landscapes).  I won’t go into the storyline in case readers haven’t seen the movie yet, but I’d like to use the world Pandora (where the movie’s action takes place) as a way to talk about other worlds and why they’re never going to be quite like they’re portrayed in the movies.  We’re all pretty used to seeing alien worlds in movies like the Star Trek franchise, Star Wars and others.  There’s a long tradition in science fiction (movies and print) of casting them as places where humans can go and explore. Hence, they kind of have to be places where humans can exist, even if they can only do it in space suits and habitats.  That’s okay — most of us have grown up knowing that humans on the Moon or Mars will be wearing space suits for a long time.  And, that will probably be the case on at least some planets that humans may one day explore beyond the solar system.

However (there’s always a gotcha), the planets have to be at least somewhat approachable and not be instant deathtraps for human explorers.  Io, in our own solar system, is a place that might be fascinating to explore, but it’s embedded in a deadly zone of radiation trapped within Jupiter’s magnetosphere.  While you could theoretically send humans there, they’d have to be really well protected — not a simple thing to do!  And, their habitats might not last very long, shortening their useful exploration time.

Pandora is a planet that seems to be set next to a Jovian-type planet in the movie Avatar. As such, if this Jovian planet is anything like the solar system’s Jupiter, there’s bound to be a HUGE magnetic field emanating from it, and magnetic fields trap charged particles. Where you have charged particles, you get radiation — and voila, Pandora could well be a deathtrap for humans. Yet, in the movie, there are humanoids living there on a lush, green world that defies current understanding of how such a world could exist next to a gas giant. And, there ARE humans there, and we ARE told that Pandora’s atmosphere is deadly to the humans but not the native humanoids.   The humans walk around with masks on (presumably sucking in oxygen), but are otherwise dressed in shirtsleeves.

So, deadly atmosphere and a presumed high-radiation environment don’t exactly say “run around in t-shirts and shorts with a mask on” to me. But hey, I’m willing to suspend disbelief for the sake of the story — I just won’t suspend the laws that govern planetary atmospheres and magnetospheres.  As beautiful as Pandora is in the movie — and hey, I hope that we DO someday find a planet as beautiful as it is — it can’t really exist in reality in the given circumstances of the movie (i.e. smack up next to a Jovian planet, embedded in its magnetosphere, and very likely also feeling the force of the Jovian’s gravity via tidal forces).

That’s just one science quibble I have with the movie. There are others — but I think you see where I’m going with this. Real-life planets around other stars are going to be far more alien than our filmmakers can imagine. They’re going to have their own life forms and appearances and environments that follow the laws of nature.  I think that someday, when our descendents are exploring those worlds, they’ll look back on our movies (if they have access to them) and probably laugh at how simplistic our viewpoint was — that we could remake worlds in our own imaginations and image and ignore the science that governs how worlds are created and how they evolve (with life or without).

All that being said, I really enjoyed the movie. I’ll probably see it again just to catch some details in the story and sets that I missed the first time around.  As long as I (and you) go into it with eyes open to the nuances and enjoy it for what it is, that’s cool.

For another scientist’s viewpoint on Avatar, go to Seth Shostak’s discussion here.



  1. Jeff in Tucson

    Jupiter is the only one of the four gas giants in our solar system which has the radiation problem that you mention. Why can’t Polyphemus (the planet in Avatar), be like Saturn or Neptune? That would solve the radiation problem. The only problem I had with the science of Pandora was that it should be tidally locked–like every large gas-giant-orbiting moon in our solar system (I think, don’t quote me on this–there may be some that aren’t, but none pop into my head). If that were the case, then we wouldn’t see majestic veiews of the planet rising and setting like we do in the movie. It would either always be in the sky or never. That would also create some pretty interesting day/night cycles too, I imagine…

  2. While I understand your issues with the movie, I feel that we don’t have an extensive sample size of what large planets may be like. We can not make general assumptions that all gas giants are like Jupiter, with intense magnetic fields and radiation belts. This makes it easier to accept Pandora as depicted.

    I would have bigger concerns with the local flora and fauna wiping out our defenseless immune systems. Not being able to cope with native bacteria, viruses and parasites is probably the most disappointing thing about visiting extra-terrestrial planets – especially one as inviting as Pandora.
    -RC Davison

  3. ccp

    I don’t disagree with either of you on the points you raise. We don’t know enough about the gas giants discovered so far to know what level of magnetic fields and radiation environments they have, but consider that if you have a gas giant, it probably will likely be structurally similar to Jupiter and Saturn — i.e. layers of conducting material beneath the cloud tops, atmospheric activity (as seen in Pandora’s primary by the giant red spot-like storm) that would interact; and conducting layers would imply magnetic fields — large planets at this level will likely have large, powerful magnetic fields. And, if there’s any source of charged particles, we’ll have a radiation environment. Those particles could come from the star in the system. So, we should, at some level, assume some radiation environment. What it is and how it affects the pandora-like planet remains TBD.

    About Saturn’s magnetosphere: I refer you to the Cassini mission site about it:

    Saturn does have a strong magnetic field and an immense magnetosphere that’s about a fifth of Jupiter’s. It is in some ways more similar to Earth’s, and it does trap radiation belt particles, and these particles reach levels similar to those of the terrestrial magnetosphere. That does imply that any world near a Saturn-like world could be affected, but that would depend on the strength of the field, etc.

    I like the point about the native flora and fauna being a danger to humans. Cameron doesn’t really address that, but it’s interesting that he addresses the CO2 atmosphere and its effect.

  4. Alex

    Also Pandora’s proximity to its parent planet seem to suggest that it’s close enough that it should experience tidal forces the likes of which Io undergoes in its orbit around Jupiter. So even worse, instead of a lush verdant paradise, we should be seeing a torn and hellish volcanic landscape.

    As pretty it is having Polyphemus hover overhead so close by, there’s no escaping its certain very powerful gravity influence.

  5. ccp

    Yup. I kind of alluded to that in the posting — and now that I think about it, it’s a good question as to whether or not Pandora could even exist. However, to get Io-like conditions, you also have to have another gravitational influence tugging at the world. In Io’s case, it’s also being tugged on by the gravitational influence of Europa, Ganymede, and Callisto. I don’t recall seeing other worlds around Polyphemus. Even if there are none, you still have to contend with the pull of the larger planet on the smaller world. Perhaps it’s breaking up and that explains those floating mountains — although I seriously doubt that a world breaking up would have any such verdant landcape on both the world and the floating mountains. Another planetary mystery — but great fun to speculate about and even learn a little about planetary science, no?

  6. Matt

    the planet that your refer to, the one which Pandora (in Avatar) seems to revolve around, could be a dead planet. It may not have a molten core, therefore no magnetic field. Much like how Mars is today.

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