Eclipses on Pandora

Started by Toliman, December 19, 2022, 03:59:12 AM

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Toliman

I am glad that we saw eclipse in TWoW because this question interested me already after first movie - I expected that eclipse should be visible on Pandorian sky.



Real Meaning Of Avatar: The Way Of Water's Eclipses Explained
https://screenrant.com/avatar-way-water-pandora-eclipses-sunsets-explained/

The third act of Avatar: The Way of Water featured a climactic battle set against an eclipse on Pandora - but what did the eclipses mean?

This article contains spoilers for Avatar: The Way of Water.


`Eylan Ayfalulukanä

As you are well aware, the day/night cycle on Pandora is a complex one because it is a moon. I'm glad the eclipse thing was shown at a couple points, it addresses a major shortccoming of the first movie.

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Toliman

Quote from: `Eylan Ayfalulukanä on December 19, 2022, 04:46:05 AMAs you are well aware, the day/night cycle on Pandora is a complex one because it is a moon. I'm glad the eclipse thing was shown at a couple points, it addresses a major shortccoming of the first movie.
Yeah, exactly. Therefore eclipse at first movie missed me a lot.

Blue Elf

Quote from: Toliman on December 19, 2022, 03:59:12 AMI am glad that we saw eclipse in TWoW because this question interested me already after first movie - I expected that eclipse should be visible on Pandorian sky.



Real Meaning Of Avatar: The Way Of Water's Eclipses Explained
https://screenrant.com/avatar-way-water-pandora-eclipses-sunsets-explained/

The third act of Avatar: The Way of Water featured a climactic battle set against an eclipse on Pandora - but what did the eclipses mean?

This article contains spoilers for Avatar: The Way of Water.


Oh, how I could leave this phenomena unnoticed? I took it just like sunset, but it is really eclipse, as sun doesn't hide itself under horizon, but is blocked by planet. It is reversed as here on Earth - eclipse is caused by Moon blocking light from sun, but Pandora is moon and light was blocked by planet. How simple, dear Watson  :)
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Toliman

Quote from: Blue Elf on December 19, 2022, 05:55:52 AM
Oh, how I could leave this phenomena unnoticed? I took it just like sunset, but it is really eclipse, as sun doesn't hide itself under horizon, but is blocked by planet. It is reversed as here on Earth - eclipse is caused by Moon blocking light from sun, but Pandora is moon and light was blocked by planet. How simple, dear Watson  :)
Yeah :) I was really surprised that some scenes with eclipse were not created already for first Avatar.

Eanikran

#5
I love this kind of stuff, I've always been a big space nerd.

If Polyphemus follows real orbital mechanics, most if not all its moons would have a tidal lock, meaning one side always faces Polyphemus while one side always faces away.

Pandora would definitely have a normal day/night cycle, but the days and nights would last much longer since they would be essentially half Pandora's orbital period (of Polyphemus).

Using Europa as an example: one Europa day is about 84 hours, since it is tidally locked to Jupiter. You'd get about 42 hours of daytime, a sunset, 42 hours of night time, then sunrise. Then because of the axial tilt (Europa's is only .1° while Pandora's is about 42°) you'd get the eclipses daily at certain times of year, but only on the side facing Jupiter.

The same applies to Pandora: sunrise, long day, sunset, long night. Then on the Polyphemus-facing side, you'd get a several hour eclipse once a day during certain times of year because of the axial tilt. On the non-Polyphemus facing side, you'd never see an eclipse, you'd only have the long day and long night, since that side never sees Polyphemus at all.

TL;DR, if you were going to live on Pandora, pick the Polyphemus side for all the cool sky vistas ;)


Toliman

Quote from: Eanikran on December 19, 2022, 12:47:42 PMI love this kind of stuff
Me too :)

Quote from: Eanikran on December 19, 2022, 12:47:42 PMIf Polyphemus follows real orbital mechanics, most if not all its moons would have a tidal lock, meaning one side always faces Polyphemus while one side always faces away.
Yeah, Pandora must have a tidal lock due to how close is to Polyphemus (we can see how huge Polyphemus is on the Pandorian sky).

Quote from: Eanikran on December 19, 2022, 12:47:42 PMThe same applies to Pandora: sunrise, long day, sunset, long night. Then on the Polyphemus -facing side, you'd get a several hour eclipse once a day during certain times of year because of the axial tilt. On the non-Polyphemus facing side, you'd never seen an eclipse, you'd only have the long day and long night.
True - therefore I expected that eclipse should be at movie, Polyphemus is in the movie visible on the Pandorian sky almost always.

Eanikran

Quote from: Toliman on December 19, 2022, 12:57:03 PM
Quote from: Eanikran on December 19, 2022, 12:47:42 PMI love this kind of stuff
Me too :)

Quote from: Eanikran on December 19, 2022, 12:47:42 PMIf Polyphemus follows real orbital mechanics, most if not all its moons would have a tidal lock, meaning one side always faces Polyphemus while one side always faces away.
Yeah, Pandora must have a tidal lock due to how close is to Polyphemus (we can see how huge Polyphemus is on the Pandorian sky).

Quote from: Eanikran on December 19, 2022, 12:47:42 PMThe same applies to Pandora: sunrise, long day, sunset, long night. Then on the Polyphemus -facing side, you'd get a several hour eclipse once a day during certain times of year because of the axial tilt. On the non-Polyphemus facing side, you'd never seen an eclipse, you'd only have the long day and long night.
True - therefore I expected that eclipse should be at movie, Polyphemus is in the movie visible on the Pandorian sky almost always.

Now that I think about it, that could explain why we didn't really see eclipses in A1 - given the 42° tilt, could have just been outside of eclipse season


Toliman

Yeah, that is good explanation :)

archaic

If we accept Pandora is tidally locked to Polyphemus, one side will always face towards Polyphemus, and will get all the eclipses, the other side always faces away from Polyphemus, and never gets an eclipse.
I'm not exactly sure how this gives rise to different seasons.
As I noted some time ago, in Avatar1, we see Jake in his Avatar getting into a cot in the Avatar house at Hell's Gate. The cot has mosquito nets (so there's something that flies and bites) but the nets are left open, so no biting flies, at least not at that moment. I interpret as a sign that there are different seasons. Having spent way way too much over thinking this (among other things), the only other alternative is that it might be weather related, but that still might well be season dependent.

Having spent the best part of 13 years considering it, I have to say that a tidaly locked Pandora doesn't fit with the first movie particularly well. It's not completely incompatible, but there needs to be a lot of explanation of things to make it fit.
I know the planetary mechanics strongly suggest that it should be, but the universe is a big place, billions of stars and many times as many planets let alone moons, just in our galaxy. Our understanding of planetary mechanics has been formed firstly from studying our own solar system, which as we discovered exoplanets, is not the only model. I feel there is ample scope for Pandora to be non tidally locked. At least in Avatar1, I've only seen it once, but I don't remember Avatar2 actually explicitly stating that Pandora is tidally locked (but I could be wrong) even if a lot on screen very very strongly implies that it is, and it is beyond me to explain (at least at this moment) how else we get what we see on screen.
Sorry, I don't mean for that to sound like a rant.Í
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Toliman

Good ideas... maybe we have intendaly such vague informations about Pandora and Polyphemus for answering of these questions.

I just recall that we already had similar discussion in one older thread, there are some ideas too:
https://forum.learnnavi.org/general-avatar-discussion/questions-about-pandora/

Tsu'roen

Quote from: archaic on December 20, 2022, 06:20:48 AMIf we accept Pandora is tidally locked to Polyphemus, one side will always face towards Polyphemus, and will get all the eclipses, the other side always faces away from Polyphemus, and never gets an eclipse.
I'm not exactly sure how this gives rise to different seasons.
As I noted some time ago, in Avatar1, we see Jake in his Avatar getting into a cot in the Avatar house at Hell's Gate. The cot has mosquito nets (so there's something that flies and bites) but the nets are left open, so no biting flies, at least not at that moment. I interpret as a sign that there are different seasons. Having spent way way too much over thinking this (among other things), the only other alternative is that it might be weather related, but that still might well be season dependent.

Having spent the best part of 13 years considering it, I have to say that a tidaly locked Pandora doesn't fit with the first movie particularly well. It's not completely incompatible, but there needs to be a lot of explanation of things to make it fit.
I know the planetary mechanics strongly suggest that it should be, but the universe is a big place, billions of stars and many times as many planets let alone moons, just in our galaxy. Our understanding of planetary mechanics has been formed firstly from studying our own solar system, which as we discovered exoplanets, is not the only model. I feel there is ample scope for Pandora to be non tidally locked. At least in Avatar1, I've only seen it once, but I don't remember Avatar2 actually explicitly stating that Pandora is tidally locked (but I could be wrong) even if a lot on screen very very strongly implies that it is, and it is beyond me to explain (at least at this moment) how else we get what we see on screen.
Sorry, I don't mean for that to sound like a rant.Í


There are at least 2 forms of tidal locking:
1. synchronously tidally locked, like our Moon -> one side of the planet/moon always faces the sun/planet it is in orbit of.
2. a spin–orbit resonance like the 3:2 spin–orbit resonance of Mercury. This means that the planet or moon does not have one fixed side always facing the sun or planet it orbits but rather rotates slowly. In the case of Mercury, it's 1.5 rotations per orbit, but other ratios are possible. This, however, requires a significantly eccentric orbit which is rather unlikely with moons.

Finally, there is also the possibility that Pandora is not yet tidally locked if the Polyphemus-Pandora system is sufficiently young (no more than about a billion years), Polyphemus relatively "light", and Pandora rather heavy and had an extremely high starting spin.
"There are many dangers on Pandora, and one of the subtlest is that you may come to love it too much" ~ Dr. Grace Augustine

"You have a strong heart. No fear. But stupid!  Ignorant like a child!" ~ Neytiri te Tskaha Mo'at'ite

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Toliman

#12
Quote from: Tsu'roen on December 25, 2022, 03:58:06 AMFinally, there is also the possibility that Pandora is not yet tidally locked if the Polyphemus-Pandora system is sufficiently young (no more than about a billion years), Polyphemus relatively "light", and Pandora rather heavy and had an extremely high starting spin.
Good idea, however there is a question whether less than billion years is sufficient time for development of highly inteligent forms of life (compare with history of our Earth).

Tìtstewan

Quote from: Tsu'roen on December 25, 2022, 03:58:06 AMFinally, there is also the possibility that Pandora is not yet tidally locked if the Polyphemus-Pandora system is sufficiently young (no more than about a billion years)
Which is very unlikely, because the Alpha Centauri star system's estimaited age is between 4.85(±0.5) and 6.52(±0.3) billion years. Pandora's rotation is pretty much locked or at least in an unknown spin–orbit resonance.

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Tsu'roen

Quote from: Tìtstewan on December 25, 2022, 08:18:52 AM
Quote from: Tsu'roen on December 25, 2022, 03:58:06 AMFinally, there is also the possibility that Pandora is not yet tidally locked if the Polyphemus-Pandora system is sufficiently young (no more than about a billion years)
Which is very unlikely, because the Alpha Centauri star system's estimaited age is between 4.85(±0.5) and 6.52(±0.3) billion years. Pandora's rotation is pretty much locked or at least in an unknown spin–orbit resonance.

Somewhere I read (can't find the source right now) that Pandora is supposedly not tidally locked.

I really hope Cameron invested some effort and hired an expert to work out the astrophysical and orbital details of the Polyphemus system and isn't just focussing on the visuals and otherwise winging it...
"There are many dangers on Pandora, and one of the subtlest is that you may come to love it too much" ~ Dr. Grace Augustine

"You have a strong heart. No fear. But stupid!  Ignorant like a child!" ~ Neytiri te Tskaha Mo'at'ite

10x (1x 2D, 3x Real 3D, 6x IMAX 3D)
1x Special Ed. (1x IMAX 3D)

Toliman

Quote from: Tsu'roen on December 28, 2022, 03:39:01 AMSomewhere I read (can't find the source right now) that Pandora is supposedly not tidally locked.
It would be surprising for me. If you find the source in future, let's share it :)

Quote from: Tsu'roen on December 28, 2022, 03:39:01 AMI really hope Cameron invested some effort and hired an expert to work out the astrophysical and orbital details of the Polyphemus system and isn't just focussing on the visuals and otherwise winging it...
Me too.

Tìtstewan

I don't have a source right at my hand, but I remember me reading that Cameron has hired or at least asked some astrophysicians.

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Flìfkxat

Quote from: Tìtstewan on December 28, 2022, 07:52:23 PMI don't have a source right at my hand, but I remember me reading that Cameron has hired or at least asked some astrophysicians.

Maybe this is what you're thinking of? It says he hired geologists and biologists as well as NASA scientists here. Not only that, but it also implies that he consulted these same scientists for TWoW as well.
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Toliman

Quote from: Tìtstewan on December 28, 2022, 07:52:23 PMI don't have a source right at my hand, but I remember me reading that Cameron has hired or at least asked some astrophysicians.
Great, it would be good :) I would expected that.

Eanikran

I'd be surprised if he didn't considering there's an entire detailed procedure for how the ISVs fly from earth to Pandora. The world building in this universe is how I got sucked in so easily back in 09