<p>Except for Rayleigh scattering (<a href="https://earthscience.stackexchange.com/questions/3063/is-the-color-of-the-sky-the-same-everywhere-on-earth">Is the color of the sky the same everywhere on earth?</a>) gases typically do not add <strong><em>any</em></strong> color to atmospheres, they are usually transparent in visible light. The Halogen gases (F<span class="math-container">$_2$</span>, Cl<span class="math-container">$_2$</span>,Br<span class="math-container">$_2$</span>, I<span class="math-container">$_2$</span>) have color though, and there are a few other colored molecular gases, but you would not expect them in planetary atmospheres.</p>

<p>The color in planetary atmospheres comes almost exclusively from particulates, such as hazes (smog basically), ice crystals (not just water), and mist with chemicals in solution. The <a href="http://en.wikipedia.org/wiki/Atmosphere_of_Titan" rel="nofollow noreferrer">atmosphere of Titan</a> is colored by tholins: organic molecules of H, N, C, O and possibly S. The <a href="http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group7rev1.shtml" rel="nofollow noreferrer">other planets' atmospheres are colored</a> by particulates such as ammonia ices (NH<sub>3</sub>), sulfuric acid droplets (H<sub>2</sub>SO<sub>4</sub>), tholins, and other exotic stuff.</p>

<p>It is important to note the color reflected or scattered by an atmosphere can be quite different than the color transmitted through an atmosphere, which is why our sky is blue in the daytime but reddish at dusk or dawn. So the color of exotic clouds or haze on other planets may look completely different seen from below rather than above.</p>

CC BY-SA 4.0
2015-10-10T17:45:47.760Z
2018-12-26T21:43:31.287Z
2018-12-26T21:43:31.287Z
Eubie Drew
<p>What are the processes, chemicals and particles involved in creating colour in a planet's sky? Could you give some examples of sky colour processes different from what happens on Earth?</p>

<atmosphere><planetary-science><clouds><atmospheric-radiation><atmospheric-chemistry>
What would a planet's sky look like with different chemical compositions, such as low nitrogen, high methane etc?
Alexninja1
# What would a planet's sky look like with different chemical compositions, such as low nitrogen, high methane etc?

(Asked by: username_0 on 2015-10-10)

What are the processes, chemicals and particles involved in creating colour in a planet's sky? Could you give some examples of sky colour processes different from what happens on Earth?

**Tags:** atmosphere, planetary-science, clouds, atmospheric-radiation, atmospheric-chemistry


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## 1 answers

### Answer by username_1 on 2015-10-10. Score: 7

Except for Rayleigh scattering ([Is the color of the sky the same everywhere on earth?](https://earthscience.stackexchange.com/questions/3063/is-the-color-of-the-sky-the-same-everywhere-on-earth)) gases typically do not add ***any*** color to atmospheres, they are usually transparent in visible light. The Halogen gases (F$\_2$, Cl$\_2$,Br$\_2$, I$\_2$) have color though, and there are a few other colored molecular gases, but you would not expect them in planetary atmospheres.

The color in planetary atmospheres comes almost exclusively from particulates, such as hazes (smog basically), ice crystals (not just water), and mist with chemicals in solution. The [atmosphere of Titan](http://en.wikipedia.org/wiki/Atmosphere_of_Titan) is colored by tholins: organic molecules of H, N, C, O and possibly S. The [other planets' atmospheres are colored](http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/periodic_table/group7rev1.shtml) by particulates such as ammonia ices (NH3), sulfuric acid droplets (H2SO4), tholins, and other exotic stuff.

It is important to note the color reflected or scattered by an atmosphere can be quite different than the color transmitted through an atmosphere, which is why our sky is blue in the daytime but reddish at dusk or dawn. So the color of exotic clouds or haze on other planets may look completely different seen from below rather than above.


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