Gas giant upper atmosphere

[Stellatus]

What would the upper atmosphere of a gas giant like Jupiter, or Neptune, look like from within the upper layers of its atmosphere?

Would it be opaque, like a gaseous soup, or would it be something like Bespin from Star Wars?

I'm asking out of personal curiosity.

This is how Bespin's "life zone" in the upper atmosphere is usually depicted:

[Don. Edwards]

It would depend on the planet. Uranus and Saturn both have a fairly hazy upper atmospheres. But Jupiter and Neptune's are fairly clear. So I don't think the depiction seen of Bespin is all that inprobable.

In any case its a decent question, but I suspect this will get moved to Purgatory. Some will not consider it hard science enough.

Don. Edwards

[Spaceman Spiff]

Actually, I think it is a good 'physics and astronomy' question, part of the "what would it look like if we were standing on...?" series .

The appearance of Bespin is, I'm sure, very typical. So long as the atmosphere is clear of coloured hazes, the physics comes down to the same scattering of sunlight by atoms and molecules of gas.

This applies to the elements hydrogen, helium, oxygen, nitrogen, and all the noble gases. The halogens are coloured: chlorine would have a pale greenish colour, bromine a brownish colour, iodine (at higher temperatures than Earth, so that it sublimates) is purple, but free halogen gases tend to be rare: nowhere in the solar system has these.

For compounds, common ones like water vapour, carbon dioxide, methane and ammonia are again colourless.

Most hazes would be white, though nitrogen dioxide would form a brown haze. Gas giants do have coloured cloud bands, caused by what I don't know, but that's the clouds not the sky.

I've seen many astronomically aware space artists paint gas giant skies like Earth's. I was hoping to point to the scientifically considered space art of William K. Hartmann in which he invariably paints gas giant skies as blue, just like Earth, but there's nothing on the internet. After much searching, I did find a small version of Adolf Schaller's stunning "Hunters, Sinkers and Floaters" showing hypothetical life on Jupiter: http://worldsofpossibility.blogspot.com/2007/07/lifes-gas-for-floater.html (third painting down). Some may recognise it from Carl Sagan's book "Cosmos".

Spiff.

[ajtribick]

Regarding sky colours, I did a rendering of what the Rayleigh scattering colours would be like on deviantART. Of course, once you get too far down in an atmosphere you start getting other effects becoming significant: multiple scattering for one. Plus the issues of clouds, coloured compounds, haze, etc.

[LordFerret]

...

I've seen many astronomically aware space artists paint gas giant skies like Earth's. I was hoping to point to the scientifically considered space art of William K. Hartmann in which he invariably paints gas giant skies as blue, just like Earth, but there's nothing on the internet. After much searching, I did find a small version of Adolf Schaller's stunning "Hunters, Sinkers and Floaters" showing hypothetical life on Jupiter: http://worldsofpossibility.blogspot.com/2007/07/lifes-gas-for-floater.html (third painting down). Some may recognise it from Carl Sagan's book "Cosmos".

Spiff.

Interesting artwork. I wish I could recall the author, Arthur C. Clarke comes to mind, a sci-fi book I'd read a long time ago inwhich airborne alien life was depicted as manta-ray looking creatures which swam in the ocean of air sucking up nutrients... grazing (if you will) on chemical clouds much like cattle on grasses. Does that ring a bell for anyone?

[The Singing Badger]

"A Meeting with Medusa" (1972). Great stuff.

[LordFerret]

That be the one!

His detailed description of such an environment and of the lifeform(s) is what struck me - and I remember more it than the actual story itself.

[The Singing Badger]

Actually, the story has no real plot, as I recall: the hero goes to Jupiter, sees some cool stuff, and goes home. The end.

By the way, there's a similar descriptive passage in 2010, where Dave Bowman flies through Jupiter's atmosphere.

[ajtribick]

I guess this is the point to ask whether anyone's read Wheelers by Ian Stewart and Jack Cohen... has some rather odd aliens in the atmosphere of Jupiter, but you'd expect that from the authors of Evolving the Alien.

[LordFerret]

No, I've not read that. I pretty much stopped reading sci-fi in the 1980's... too busy with work. I did read 2010 however, and I do remember the passage, but it didn't stick out in my mind nearly as much as the first reference.

[bdm]

The sky colour would depend to some extent on the spectral class of the local sun. A red dwarf star wouldn't create the same vivid blue skies that a sunlike star would.

[The Singing Badger]

I guess this is the point to ask whether anyone's read Wheelers by Ian Stewart and Jack Cohen... has some rather odd aliens in the atmosphere of Jupiter, but you'd expect that from the authors of Evolving the Alien.

That reminds me of Iain Banks's The Algebraist, which also has wheel-shaped aliens living in the depths of gas giants. (But like all Iain Banks 'aliens', they still behave like semi-inebriated Scotsmen...)

[Stellatus]

The sky colour would depend to some extent on the spectral class of the local sun. A red dwarf star wouldn't create the same vivid blue skies that a sunlike star would.

The world in question, my fictional planet Heracles, does in fact orbit a sunlike star. So, everything is good and done here! Thanks for the help, fellers!

[eburacum45]

Here's an image of air-borne plant-life mat-islands which I've made for Orion's Arm;
http://www.orionsarm.com/worlds/sky%5B2%5D.jpg

on a Jupiter like world the lower clouds could be stained with brownish compounds, the exact nature of which I don't know exactly. But the sky would probably be blue.

[rthorvald]

After much searching, I did find a small version of Adolf Schaller's stunning "Hunters, Sinkers and Floaters" showing hypothetical life on Jupiter.

Wubs...

(Click for full-size)

- rthorvald

[Fenerit]

Great! What version of Celestia get it?

[rthorvald]

Great! What version of Celestia get it?

That??s from my Ran III project, which will be released when 1.5 final is out.

- rthorvald

[eburacum45]

Spaceman Spiff pointed out some really good references on sky colour and pressure; two pdfs by Bohren and Fraser on atmopsheric optics. I've used them to update the Orion's Arm page on sky colour
here
http://www.orionsarm.com/whitepapers/sk ... orlds.html
the references at the bottom of the page take you to Bohren and Fraser's work (note: pdf files.)

I've also put a link to Chaos Syndrome's page about star colour and skycolour, which is very interesting and colourful.

[m1omg]

John Whatmough did a good job in depicting exoplanets;

http://www.extrasolar.net/planettour.as ... anetId=158

Gas giants in the habitable zone will probably have skies similar to Earth's (so the Bespin's sky is depicted correctly).