<p>On Mars, <a href="https://astronomy.stackexchange.com/a/10772/7982">it's pink because of the rust in the air</a>. But it's blue near the sunset, where light doesn't get to bounce off the iron and be reflected red.</p>
<p><a href="https://i.sstatic.net/9Q0ZWzJK.jpg" rel="noreferrer"><img src="https://i.sstatic.net/9Q0ZWzJK.jpg" alt="enter image description here" /></a></p>
<p>On Venus, it's yellow because of  sulfuric acid gas. Note the white object on the ground:</p>
<p><a href="https://i.sstatic.net/LhvVnUhd.jpg" rel="noreferrer"><img src="https://i.sstatic.net/LhvVnUhd.jpg" alt="" /></a></p>
<p>Titan sky is blue with yellow sunsets, according to <a href="https://free-astro.org/titan/" rel="noreferrer">this rigorous simulation</a>:</p>
<p><a href="https://i.sstatic.net/Z4gUIUWm.png" rel="noreferrer"><img src="https://i.sstatic.net/Z4gUIUWm.png" alt="enter image description here" /></a></p>
<p>All other planets either</p>
<ul>
<li><p>Only have a hard surface thousands of mles deep, or</p>
</li>
<li><p>Have no atmosphere, and a black sky.</p>
</li>
</ul>

CC BY-SA 4.0
2024-06-17T18:25:19.740Z
2024-06-17T22:34:52.403Z
2024-06-17T22:34:52.403Z
Miss Understands
<p>The color you can see in the sky depends on two things, first the color (if you want to be more specific, the emission spectra of the light of the star) of the light shining, this is the Sun in our case (but may be another star in order to answer your question about outside the solar system), and second depends on the chemical components of the atmosphere of the planet in question, because this atmosphere is the reason for what is called the absorption lines. </p>

<p>Absorption light is something like that, if you have white light and a gas with green absorption lines, then after crossing the gas the light will turn the opposite of green, I don't know what color that is. </p>

<p>In conclusion if our atmosphere changes (for some unknown reason) here on planet Earth, then the color of the sky is going to change. </p>

CC BY-SA 4.0
2019-01-21T11:07:06.030Z
Absorption plus scattering of different types plus refraction. Based on absorption only we would have a sun white sky dome here on earth. But correct is with a change in atmosphere we might see change in colours.
Alchimista
CC BY-SA 4.0
2019-02-12T03:09:11.573Z
I have to comment that the sky on Earth varies considerably in color. It can change with season, time of day, atmospheric contaminants, etc. However, I guess that most people would consider the sky to be blue.
Jack R. Woods
CC BY-SA 4.0
2019-01-21T03:29:18.610Z
2019-01-21T06:32:06.400Z
2019-01-21T06:32:06.400Z
Gabriel Palau
<p>Atmospheric color has to do mainly with how the elements that make up the atmosphere scatter light. On Earth, the atmosphere of around 20% <span class="math-container">$\require{mhchem}\ce{O2}$</span> scatters higher-frequency wavelengths such as the blues and ultraviolets, which gives it its blue hue. On Luna there is an extremely sparse exosphere which does not noticeably scatter light, which in turn causes the sky to be black even though it receives the exact same amount of solar radiation as the top of Earth's atmosphere.</p>
<p>Same story with Mercury as Luna: an extremely thin exosphere causes the sky to be black. Venus is cloaked in a thick atmosphere of carbon dioxide, both the thickness and composition of which is responsible for the orange atmosphere you would see on the surface (if you survived long enough to see the surface). Mars has a thin <span class="math-container">$\ce{CO2}$</span> atmosphere, which gives an orangish-brown sky.</p>
<p>As for the gas giants I don't know off the top of my head, though there is a NASA simulation that shows sunset colors on some of the gas/ice giants if you can find that.</p>

CC BY-SA 4.0
2024-06-18T03:30:33.737Z
I've edited your answer, but as a new contributor it might be worth reviewing the [help] topics and looking at how other answers are written so you get a better idea of our site's expectations. The [answer] page notes that "We don't expect every answer to be perfect, but answers with correct spelling, punctuation, and grammar are easier to read. They also tend to get upvoted more frequently."
Chappo Hasn't Forgotten
CC BY-SA 4.0
2024-06-18T04:41:13.040Z
@ChappoHasn'tForgotten you have put superscript instead of subscript for the chemical formulas :)
Nilay Ghosh
CC BY-SA 4.0
2024-06-19T00:33:46.690Z
@NilayGhosh Good point! Most people don't know, but we can also turn on the Chemistry package for Mathjax any time we want it (see edit).
uhoh
CC BY-SA 4.0
2024-06-19T09:25:07.533Z
Thanks @NilayGhosh – no wonder it didn't look right. Clearly I shouldn't do editing before I've had my morning coffee. Thanks also to @ uhoh for the repair work :-)
Chappo Hasn't Forgotten
CC BY-SA 4.0
2024-06-19T19:50:15.647Z
Thanks @ChappoHasn'tForgotten, ill remember that next time! Though it does look like you switched O2 to CO2 when describing Earth's atmosphere, I'll go fix that though.
ArchiveOfStars
CC BY-SA 4.0
2024-06-19T19:57:53.903Z
Never mind, looking at the edit log it looks like it was @uhoh who changed o2 to co2, no worries though
ArchiveOfStars
CC BY-SA 4.0
2024-06-21T02:09:28.527Z
Yeah, not me. 20% CO$_2$ on Earth would create a wonderful hothouse for tropical vegetation but would wipe out most animals & dissolve all coral reefs! NB: Raleigh scattering is also caused by atmospheric N$_2$. PS An interesting corollary: the blue sky on Earth scales to black as you gain altitude (less atmosphere for scattering). At 5,000m (e.g. the Bolivian altiplano & Atacama desert), the sky overhead is a startlingly vivid, deep blue – almost indigo. No doubt the extreme dryness there further reduces scattering too.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2024-06-21T04:25:26.807Z
@ChappoHasn'tForgotten you know, that leads me to wonder exactly how much oxygen contributes to atmospheric color, titan, with an atmosphere of mostly nitrogen, has a distinctly orange sky, is that why sunsets are orange? Blue light being absent and the nitrogen scattering the orange?
ArchiveOfStars
CC BY-SA 4.0
2024-06-21T05:01:24.127Z
The image in [this answer](https://astronomy.stackexchange.com/a/57924/14094) suggests Titan has a blue sky from Raleigh scattering (like Earth) but the Sun appears red/orange/yellow on the horizon because of absorption of shorter frequencies (like Earth). However, this might be the basis for a good question about the difference in Raleigh scattering in N$_2$-rich atmospheres when O$_2$ is present. And/or: when we analyse a star's light through the atmosphere of its exoplanet, is Raleigh scattering a factor or is that only observed from "beneath" the sky (i.e. on the planet's surface)?
Chappo Hasn't Forgotten
CC BY-SA 4.0
2024-06-16T15:41:32.293Z
2024-06-19T19:50:55.583Z
2024-06-19T19:50:55.583Z
ArchiveOfStars
<p>On Earth, the sky is blue.</p>

<p>What color would the sky be on other planets in our solar system? What about outside the solar system? Are there planets with purple skies, or green skies? Or are the all just blue?</p>

CC BY-SA 4.0
2019-01-19T21:32:12.067Z
We have seen pictures from Mars and Venus. They aren't blue:-)
Rory Alsop
CC BY-SA 4.0
2019-01-19T21:39:38.070Z
[On Mars, the sky is red and the sunset is blue](https://astronomy.stackexchange.com/q/10771/5264)
pela
CC BY-SA 4.0
2019-01-20T02:09:22.837Z
[Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?](https://astronomy.stackexchange.com/q/24048/7982)
uhoh
CC BY-SA 4.0
2019-01-21T11:00:20.150Z
Also https://astronomy.stackexchange.com/questions/24804/do-the-gases-in-the-earths-atmosphere-affect-the-color-of-a-lunar-eclipse
Alchimista
CC BY-SA 4.0
2019-01-21T11:02:20.857Z
https://space.stackexchange.com/questions/24108/why-would-mars-sky-appear-blue-at-dawn-and-dusk-but-red-during-the-middle-of-t
Alchimista
<planet><planetary-atmosphere><atmospheric-effects>
What color is the Sky on other Planets?
PotatoLatte
# What color is the Sky on other Planets?

(Asked by: username_0 on 2019-01-19)

On Earth, the sky is blue.

What color would the sky be on other planets in our solar system? What about outside the solar system? Are there planets with purple skies, or green skies? Or are the all just blue?

**Tags:** planet, planetary-atmosphere, atmospheric-effects

> **Comments:**
> **username_1**: We have seen pictures from Mars and Venus. They aren't blue:-)  
> **username_2**: [On Mars, the sky is red and the sunset is blue](https://astronomy.stackexchange.com/q/10771/5264)  
> **username_3**: [Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?](https://astronomy.stackexchange.com/q/24048/7982)  
> **username_4**: Also https://astronomy.stackexchange.com/questions/24804/do-the-gases-in-the-earths-atmosphere-affect-the-color-of-a-lunar-eclipse  
> **username_4**: https://space.stackexchange.com/questions/24108/why-would-mars-sky-appear-blue-at-dawn-and-dusk-but-red-during-the-middle-of-t  

---

## 3 answers

### Answer by username_5 on 2024-06-17. Score: 6

On Mars, [it's pink because of the rust in the air](https://astronomy.stackexchange.com/a/10772/7982). But it's blue near the sunset, where light doesn't get to bounce off the iron and be reflected red.

[![enter image description here](https://i.sstatic.net/9Q0ZWzJK.jpg)](https://i.sstatic.net/9Q0ZWzJK.jpg)

On Venus, it's yellow because of sulfuric acid gas. Note the white object on the ground:

[![](https://i.sstatic.net/LhvVnUhd.jpg)](https://i.sstatic.net/LhvVnUhd.jpg)

Titan sky is blue with yellow sunsets, according to [this rigorous simulation](https://free-astro.org/titan/):

[![enter image description here](https://i.sstatic.net/Z4gUIUWm.png)](https://i.sstatic.net/Z4gUIUWm.png)

All other planets either

* Only have a hard surface thousands of mles deep, or
* Have no atmosphere, and a black sky.


---

### Answer by username_6 on 2019-01-21. Score: 3

The color you can see in the sky depends on two things, first the color (if you want to be more specific, the emission spectra of the light of the star) of the light shining, this is the Sun in our case (but may be another star in order to answer your question about outside the solar system), and second depends on the chemical components of the atmosphere of the planet in question, because this atmosphere is the reason for what is called the absorption lines.

Absorption light is something like that, if you have white light and a gas with green absorption lines, then after crossing the gas the light will turn the opposite of green, I don't know what color that is.

In conclusion if our atmosphere changes (for some unknown reason) here on planet Earth, then the color of the sky is going to change.

> **Comments:**
> **username_4**: Absorption plus scattering of different types plus refraction. Based on absorption only we would have a sun white sky dome here on earth. But correct is with a change in atmosphere we might see change in colours.  
> **username_7**: I have to comment that the sky on Earth varies considerably in color. It can change with season, time of day, atmospheric contaminants, etc. However, I guess that most people would consider the sky to be blue.  

---

### Answer by username_8 on 2024-06-16. Score: 1

Atmospheric color has to do mainly with how the elements that make up the atmosphere scatter light. On Earth, the atmosphere of around 20% $\require{mhchem}\ce{O2}$ scatters higher-frequency wavelengths such as the blues and ultraviolets, which gives it its blue hue. On Luna there is an extremely sparse exosphere which does not noticeably scatter light, which in turn causes the sky to be black even though it receives the exact same amount of solar radiation as the top of Earth's atmosphere.

Same story with Mercury as Luna: an extremely thin exosphere causes the sky to be black. Venus is cloaked in a thick atmosphere of carbon dioxide, both the thickness and composition of which is responsible for the orange atmosphere you would see on the surface (if you survived long enough to see the surface). Mars has a thin $\ce{CO2}$ atmosphere, which gives an orangish-brown sky.

As for the gas giants I don't know off the top of my head, though there is a NASA simulation that shows sunset colors on some of the gas/ice giants if you can find that.

> **Comments:**
> **username_9**: I've edited your answer, but as a new contributor it might be worth reviewing the [help] topics and looking at how other answers are written so you get a better idea of our site's expectations. The [answer] page notes that "We don't expect every answer to be perfect, but answers with correct spelling, punctuation, and grammar are easier to read. They also tend to get upvoted more frequently."  
> **username_10**: @username_9 you have put superscript instead of subscript for the chemical formulas :)  
> **username_3**: @username_10 Good point! Most people don't know, but we can also turn on the Chemistry package for Mathjax any time we want it (see edit).  
> **username_9**: Thanks @username_10 – no wonder it didn't look right. Clearly I shouldn't do editing before I've had my morning coffee. Thanks also to @ username_3 for the repair work :-)  
> **username_8**: Thanks @username_9, ill remember that next time! Though it does look like you switched O2 to CO2 when describing Earth's atmosphere, I'll go fix that though.  
> **username_8**: Never mind, looking at the edit log it looks like it was @username_3 who changed o2 to co2, no worries though  
> **username_9**: Yeah, not me. 20% CO$_2$ on Earth would create a wonderful hothouse for tropical vegetation but would wipe out most animals & dissolve all coral reefs! NB: Raleigh scattering is also caused by atmospheric N$_2$. PS An interesting corollary: the blue sky on Earth scales to black as you gain altitude (less atmosphere for scattering). At 5,000m (e.g. the Bolivian altiplano & Atacama desert), the sky overhead is a startlingly vivid, deep blue – almost indigo. No doubt the extreme dryness there further reduces scattering too.  
> **username_8**: @username_9 you know, that leads me to wonder exactly how much oxygen contributes to atmospheric color, titan, with an atmosphere of mostly nitrogen, has a distinctly orange sky, is that why sunsets are orange? Blue light being absent and the nitrogen scattering the orange?  
> **username_9**: The image in [this answer](https://astronomy.stackexchange.com/a/57924/14094) suggests Titan has a blue sky from Raleigh scattering (like Earth) but the Sun appears red/orange/yellow on the horizon because of absorption of shorter frequencies (like Earth). However, this might be the basis for a good question about the difference in Raleigh scattering in N$_2$-rich atmospheres when O$_2$ is present. And/or: when we analyse a star's light through the atmosphere of its exoplanet, is Raleigh scattering a factor or is that only observed from "beneath" the sky (i.e. on the planet's surface)?  

---

