questions about pandora

Started by emanresu, October 18, 2019, 03:08:46 PM

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emanresu

Hello;

Don't know if this is the right forum for asking this but....

Does anyone know the specifics of the Pandora moon's orbit around Polyphemus? (distance from the primary, length of month/time of orbit, etc)

Can anyone tell me the length of the Pandoran day?

And most importantly since James Cameron never seems to cover this, is Pandora tidally locked to Polyphemus?
If not, how does Cameron justify this?

Thanks. Have looked online, but cannot find any information on this.

Toliman

Kaltxì ma emanresu :) Welcome here!

This are difficult but interesting questions.

Maybe you already found this picture too:
http://orig07.deviantart.net/a5e6/f/2013/088/8/c/avatar__the_alpha_centauri_system_by_okiir-d5zo7h9.png

Something little is here:
https://james-camerons-avatar.fandom.com/wiki/Pandora

Quote from: emanresu on October 18, 2019, 03:08:46 PM
And most importantly since James Cameron never seems to cover this, is Pandora tidally locked to Polyphemus?
If not, how does Cameron justify this?
I would expect that Pandora must be tidally locked to Polyphemus due to relative proximity of Pandora to Polyphemus, however I didn't found nothing about it. If not, I would be very interested too ;D


archaic

Welcome emanresu.


I would dearly like to know the answers to these questions as well.

I have seen a good bit of speculation about these, but nothing cannon.

If Pandora is not tidally locked, it may be due to the other moons in orbit around Polyphemus causing sufficient gravitational disturbance that a tidal lock hasn't formed, at least not yet.

If you do find the answers, please, please, please do come back and share them, I know a lot of us here would love to know!

:D  :D
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Toliman

Quote from: archaic on October 23, 2019, 01:29:15 PM
If Pandora is not tidally locked, it may be due to the other moons in orbit around Polyphemus causing sufficient gravitational disturbance that a tidal lock hasn't formed, at least not yet.
Hmm, maybe it's possible too however it would be really big gravitational disturbances, when we consider that all big (+ many smaller) moons at solar systems are tidal locked (for example, eight the closest moons of Jupiter or all five big moons of Uranus). Also, Pandora sure orbiting Polyphemus in small distance (when we consider how big is polyphemus on Pandorian sky) and I would say that gravity of Polyphemus must be dominant in this distance.

archaic

Agreed. Tidally locked is highly likely, which means that some parts of Pandora would never see Polyphemus.
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Toliman

#5
Hmm, still thinking about several things.

Here
http://orig07.deviantart.net/a5e6/f/2013/088/8/c/avatar__the_alpha_centauri_system_by_okiir-d5zo7h9.png
is writen that in adition, its (Pandorian) elliptical orbit produces seasonal temperarure variations and a range in daytime illumination of about ten percent.

If it's right, in this case (elliptical orbit with such significant eccentricity) Pandora would  be in same situation as Jupiter's moon Io where tidal heating (caused right by orbital eccentricity in conjunction with proximity of Io to Jupiter) causes extremelly strong volcanic activity.
https://en.wikipedia.org/wiki/Volcanology_of_Io
It must be really significant if we consider proximity of Pandora to Polyphemus (and strong impact of Polyphemus gravity on Pandora). Well, surely there are volcanoes on Pandora, however (if information from that link are right) I am afraid whether Pandora would not be rather "volcanic hell" than that nice and amazing world which we know...


archaic

Pandora can't be tidally locked, or a Pandoran day/night cycle would be one full orbit of Pandora around Polyphemus.

One Pandoran day would be the same as one Pandoran month, and I do not believe that matches up with the movie.

I think.
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Toliman

Sure, in case of pandora tidally locking Pandorian day/night cycle would be same as Pandorial orbital period. Buth due to proximity of Pandora to Polyphemus (consider how big Polyphemus is on the pandorian sky) is possible that Pandora orbital period could be very short (even is possible that it could be shorter than one Earth day).

Also I am not able imagine what would be able prevent to tidal locking of Pandora because impact of mother planet gravity is really important for such close moons.

But it's just my ideas, there is too many things which we don't know so I can be wrong.

archaic

Presumably Pandora would have started out with rotation, the effect of Polyphemus's gravity would gradually slow it dowb. Is it possible that Pandora started out with sufficient rotation speed to still be rotating?
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Toliman

It's interesting idea. But I am afraid that Pandora would have to be far more distant (from Polyphemus) in order this (or initial rotation of Pandora would be really insane). Impact of gravity is really important in area close to mother planet.

However, as I wrote, we would to have more information about Polyphemus and Pandora to answer of this question :-\

archaic

I strongly suspect the information we have is intentionally vague.
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Toliman

Yeah, I have exactly this idea too.

Toliman

And also I have one thing which I very like to know:

Paul Frommer recently gave us few new words:
http://naviteri.org/2019/06/50a-liu-amip-40-new-words%EF%BB%BF/

between which is also Na'vi name for star Proxima Centauri: Tawsnrrtsyìp
He wrote:
QuoteAs for C, litte Proxima Centauri, the Na'vi don't think of it as a sun at all but rather as the little lamp in the sky, Tawsnrrtsyìp, from taw 'sky' + sänrr 'lamp' + tsyìp 'diminutive.'

What is strange for me - why Na'vi named right this star as "the little lamp in the sky"? How they would recognize that this star is not only "common star"?

Proxima Centauri is star with very low luminosity and even from near Alpha Centauri her brightness would be only 4.5 mag which mean that this star could be visible by naked eye (on dark sky, but there is light of Polyphemus and Polyphemus's other moons on Pandorian sky) but it would be just "one common faint star", really too faint for thinking of this star as "the little lamp in the sky".
Theoretically they could record (across few generations, if Na'vi would record moving of celestial bodies) proper motion of Proxima Centauri on Pandorian sky (it could be sufficient reason why give any special name to this star) but orbital period of Proxima Centauri is extremelly long, arrox. 500000 years, which means that shifting obout 0.5 degree (=diameter of Moon on Earth sky) would take approx. 700 years - long time and also I am affraid that for Na'vi would be very difficult recognize al all that right this one faint star (one from several hundreds) change his position due extremely light pollution causes by Polyphemus and another moons.