# What colour would the sky of a high-oxygen, high-argon, high-water vapour atmosphere be?

Although this is a hypothetical, I think it is nevertheless a legitimate physics problem. I would very much appreciate any answers you can give.

What colour would the sky be, both at daytime and at nighttime, on a small (little over mars-size) moon located 150.3 million km from its yellow dwarf binary star with an unusually high atmospheric temperature and an atmosphere with the following composition: Argon- 80% Oxygen- 12% Nitrogen- 5% Hydrogen- 0.73% Neon- 0.22% Carbon dioxide- 0.05%

There are also thin-spread particles of Zincite floating around in the outer atmosphere due to volcanic eruptions millions of years ago. The sky of this world is high in water-vapour, the average humidity being about 70%. The atmospheric density is 50x that of earth.

• There was a little discussion of this in chat. The calculations for this are horrendous and evil, but they can be done. That suggests that maybe this could be rephrased somewhat and posted to Physics SE, where there are bound to be lots of people who know how to answer accurately. This isn't off-topic, but I worry that you won't have a lot of luck getting a clean answer here.
– CAgrippa
Commented Mar 16, 2016 at 19:45
• Okay, thank you. Could you recommend how I reword it?
– IJoinedCozIcan
Commented Mar 16, 2016 at 20:10
• "Although this is a hypothetical, I think it is nevertheless a legitimate physics problem." {insert question text here} That'd probably do it.
– CAgrippa
Commented Mar 16, 2016 at 20:29
• I think you'll need to specify the atmosphere's density as well as its composition. At one extreme, if the density is 0.00001% of the Earth's atmosphere, the sky will be black. Commented Mar 16, 2016 at 20:45
• IS there a reason these numbers are specific, also, how far would you be willing to bend these numbers? The 2 main factors of the color of the sky is the color of the Star and how well the atmosphere scatters its light. Really, though, because the gases are probably colorless, the biggest difference is probably the yellow star itself, Rayleigh scattering of yellow light in argon gas is probably the color of your sky, if you can even see it in all that gas.
– Ryan
Commented Mar 16, 2016 at 20:58