<p>I think your issue is linguistic not astronomical. The way a language cuts up the space of colours into discrete names is varies strongly from one language to another, and even from one dialect to another. Translating colour names is fraught with difficulty.</p>
<p>Uranus has a colour that is approximated by an RGB value with approximately equal amounts of green and blue (I've found the value #B2D6DB, but monitors vary, so this isn't absolute). You might describe this as &quot;light green-blue&quot; or &quot;light blue-green&quot; or &quot;pale teal&quot; or &quot;pale aqua&quot; or &quot;duck-egg&quot;, or some form of &quot;turquoise&quot;.</p>
<p>However, the usual contrast in terms of colour is with Neptune, which much closer to an azure or cerulean blue. Uranus may not be &quot;green&quot;, but it is &quot;greener than Neptune&quot;.</p>
<p>The images below show the RGB value and a <a href="https://www.planetary.org/space-images/uranus-on-september-20-2015" rel="noreferrer">colour photo of Uranus by an Earth based observer</a> which shows a turquoise colour</p>
<p><a href="https://i.sstatic.net/hGHLUm.png" rel="noreferrer"><img src="https://i.sstatic.net/hGHLUm.png" alt="enter image description here" /></a><a href="https://i.sstatic.net/dICV7.png" rel="noreferrer"><img src="https://i.sstatic.net/dICV7.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2023-09-17T06:50:58.970Z
(+1) Nice answer!, I also faced the same problem while comparing the wavelength to the color, I couldn't find a color for the peak wavelength
Arjun
CC BY-SA 4.0
2023-09-17T07:22:45.563Z
Thats nice. Got much clarity regarding this issue. Thank you :)
Dhruv Nayak
CC BY-SA 4.0
2023-09-17T07:25:16.347Z
Actually, I have to explain this to 6th graders and I wasn't exactly able to understand how to explain this to them, since, I myself was a bit perplexed by reading the info. available on the internet.
Dhruv Nayak
CC BY-SA 4.0
2023-09-17T09:31:54.987Z
Related article to differentiating between green/blue: https://www.nature.com/articles/s41599-019-0341-7 and https://onlinelibrary.wiley.com/doi/full/10.1111/ssqu.13074
samcarter_is_at_topanswers.xyz
CC BY-SA 4.0
2023-09-17T09:53:40.283Z
@samcarter your second link is irrelevant as it is about perceoptions of "Green spaces" ie opinions about parks and gardens; not about colour.
James K
CC BY-SA 4.0
2023-09-17T09:55:10.393Z
The image is cropped from four - each of them shows the same basic color, even the infrared ones. This one is called "straight RGB" but no information is given about color correction, white balance, etc. There's no reason to believe this one has any bearing on the "true color" of the light, which is a murky concept at best to begin with (cf. [Billmeyer and Saltzman's Principles of Color Technology](https://onlinelibrary.wiley.com/doi/book/10.1002/9781119367314) 3rd/4th edition) The image's color has been process SEVERAL times, for "internet color" possibly for your device's screen's pallet.
uhoh
CC BY-SA 4.0
2023-09-17T10:00:08.797Z
to even begin to get "the color of Neptune" it will take either a proper RGB recording through a good quality Bayer filter followed by fastidious color correction for the camera's own bias, or better yet, staring from a recorded, calibrated photometric spectrum, then apply the proper projection on to RGB space. *Good luck!*  See for example [this answer to *Need help simulating solar limb darkening*](https://space.stackexchange.com/a/16639/12102)
uhoh
CC BY-SA 4.0
2023-09-17T18:43:06.433Z
"Translating colour names is fraught with difficulty." - **So is specifying colours objectively**. Monitor RGB values simply won't do it, for a [large number of reasons](https://poynton.ca/ColorFAQ.html). Better to speak in terms of the spectrum that is actually reflected from the planet's surface (intensity at each wavelength), either with or without the filtering of Earth's atmosphere.
Karl Knechtel
CC BY-SA 4.0
2023-09-17T19:34:35.527Z
@KarlKnechtel I agree completely.  ..."colours are hard"... But working with spectra is well beyond what is needed to explain this to a bunch of sixth grade kids.  All you need is "It looks greeny-blue.  More green than Neptune (because of the methane)"  In this sense #B2D6DB is a "lie to children".
James K
CC BY-SA 4.0
2023-09-17T22:23:36.520Z
Specifying or reproducing colors is immensely complicated, but you don't really need an objective definition of what exact shades qualify as "green" here. If you show someone pictures of Neptune and Uranus taken with similar processing, as long as it's reasonably accurate, and say "the green one", it'll be immediately obvious which one is meant. It's not really an attempt to describe the precise color.
Christopher James Huff
CC BY-SA 4.0
2023-09-18T04:47:33.640Z
Color names being cultural is indeed an interesting problem (btw for me the included picture seems a lot closer to green than to blue). There is an interesting myth about people in ancient times not being able to perceive the color blue, because in the oldest ancient Greek texts don't mention the color blue, and many things we consider to be blue (the sky, or the ocean) are described by other means. However, it is most likely cultural, as for example what we call "white wine" does not look like milk, so why call it white? And the skin color of what we call white people is also not like milk.
vsz
CC BY-SA 4.0
2023-09-18T13:38:00.137Z
@JamesK Oh, sorry! I must have mixed up the links when copying them into the comments. Sorry for the confusion!
samcarter_is_at_topanswers.xyz
CC BY-SA 4.0
2023-09-18T21:19:49.263Z
@JamesK why are the other infrared images that you cropped away from this one also the same color? https://i.sstatic.net/Fon8j.jpg Don't you think it's much more likely that the author chose a color they liked and made all four the some color using artistic license? In which case isn't this answer of zero scientific value and quite misleading? Of course to some that doesn't matter as long as those reputation points keep rolling in but YOU SHOULD HAVE SHOWN THE OTHER THREE IMAGES rather than crop them out so folks have a better idea what this one is or isn't in terms of color representation
uhoh
CC BY-SA 4.0
2023-09-18T21:29:28.753Z
I don't know why you're getting angry.  Its an IR filter, to bring out clouds, and not a infrared image (in the way that JWST are infrared.  I cropped so it would fit on a screen better, the original is linked.  As of "of zero scientific value", you are just ranting at this point. and the shouting doesn't help.
James K
CC BY-SA 4.0
2023-09-19T06:19:15.367Z
Assuming the RGB given is the whole story (despite some comments to the contrary), it's also almost as red, so one could make a case for calling it _grey_.
J.G.
CC BY-SA 4.0
2023-09-19T08:06:33.557Z
the primary colors of paint (reflect light) are red yellow and blue; the primary colors of light (emitting) are red green and blue; the other colors are composed from these; so equal amounts of red and green, with less or zero blue, is yellow; equal amounts of green and blue, with less or zero red, is **cyan** or turquoise, the color of Uranus; equal amounts of red and blue, with less or zero green, is magenta (pink)
jmarina
CC BY-SA 4.0
2023-09-19T10:24:12.613Z
A point that might be relevant to the discussion: many cultures don't really have much of a clear separation between green and blue, which are often considered varying shades of some underlying unified color. Even in Japanese and Chinese, two quite significant cultures, has this been true historically (Japanese "ao"/"aoi" and Chinese "qīng", both meaning either "blue" or "green" depending on context).
Outis Nemo
CC BY-SA 4.0
2023-09-17T06:43:06.473Z
2023-09-17T06:43:06.473Z
James K
<p>This answer looks into why Uranus is &quot;green&quot; <em>or at least <strong>greener</strong></em> compared with Neptune's blue.</p>
<p>Both planets have similar atmospheric compositions and would ordinarily be expected to show similar colors. But according to a <a href="https://noirlab.edu/public/news/noirlab2211/" rel="noreferrer">study by the National Science Foundation's NOIRLab program</a>, the greater atmospheric activity of Neptune's atmosphere tends to break up the smog of more complex hydrocarbons which, on Uranus, tends to make the externally observed color of Uranus whiter and greener than the methane would otherwise be expected to give. The technical reference is from [Irwin et al.<a href="https://i.sstatic.net/TPjKx.png" rel="noreferrer">1</a>](<a href="https://doi.org/10.1029/2022JE007189" rel="noreferrer">https://doi.org/10.1029/2022JE007189</a>), and is open access. The figure below, taken from this reference, shows the brighter transmission in Neptune at blue and violet wavelengths compared with Uranus, whereas Uranus becomes slightly brighter at longer wavelengths and less blue/violet selective overall.</p>
<p><a href="https://i.sstatic.net/TPjKx.png" rel="noreferrer"><img src="https://i.sstatic.net/TPjKx.png" alt="enter image description here" /></a></p>
<p>We actually see a similar effect on Earth. In <a href="https://earthscience.stackexchange.com/questions/24623/why-does-earths-atmosphere-have-a-whiter-color-near-the-horizon">this question</a> the whitening of the sky near the horizon is discussed in terms of increased Rayleigh scattering, which would be caused by the smoggy conditions on Uranus too. One answer demonstrates through photography that the sky hue on Earth also tends to become greener as it becomes whiter, matching well with the difference between Uranus and Neptune.</p>
<p><strong>Reference</strong> (open access)</p>
<ol>
<li>Irwin, P. G. J., Teanby, N. A., Fletcher, L. N., Toledo, D., Orton, G. S., Wong, M. H., et al. (2022). &quot;Hazy blue worlds: A holistic aerosol model for Uranus and Neptune, including dark spots&quot;. <em>Journal of Geophysical Research: Planets</em>, <strong>127</strong>, e2022JE007189. <a href="https://doi.org/10.1029/2022JE007189" rel="noreferrer">https://doi.org/10.1029/2022JE007189</a></li>
</ol>

CC BY-SA 4.0
2023-09-25T07:09:34.107Z
It's amazing that the spectra of Neptune and Uranus are almost identical!
ayr
CC BY-SA 4.0
2023-09-17T21:00:58.537Z
2023-09-19T09:33:14.837Z
2023-09-19T09:33:14.837Z
Oscar Lanzi
<p>This is just a mere illusion. In reality, the peak wavelength is actually between green and blue, that is slightly cyanish/turquoise. The reason this happens is because the atmosphere of Uranus contains methane, which has an absorption wavelength between yellow to red leading to blue/green reflected wavelength. In the albedo of 30% of the sunlight reflected by Uranus, blue green light is absorbed the most.</p>
<p>This wavelength is however scattered in our atmosphere, via atmosphere refraction, specifically <a href="https://en.wikipedia.org/wiki/Rayleigh_scattering#From_molecules" rel="nofollow noreferrer">Rayleigh scattering</a> which leads to telluric absorption which leads to a few wavelengths being scattered more like blue wavelengths, which is precisely observed in the ground-based telescope images. In space-based telescopes where there is nill telluric scattering, the actual color is perceived.</p>
<p>Even though the green color is more sensitive to our light cones, green light is already absorbed by our atmosphere, before reaching our eye.</p>
<p>This is quite similar to how the Sun's peak wavelength is green, but we perceive it as yellow, except the atmospheric refraction is different in this case.</p>
<p>Space telescope:</p>
<p><a href="https://i.sstatic.net/Y52h6.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Y52h6.png" alt="Enter image description here" /></a></p>
<p>vs.</p>
<p>Ground-based telescope:</p>
<p><a href="https://i.sstatic.net/eTtUq.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/eTtUq.png" alt="Enter image description here" /></a></p>
<p>It's not leaned towards pure green or pure blue. The Rayleigh scattering absorbs only few nms, like around 30-40 nm.</p>
<p>In conclusion:</p>
<p>This is a mere mirage by the atmospheric scattering of the Earth, aerosols like to absorb more green than blue due to their electrons and quantum mechanics even though Uranus is lying between <em>green</em> and <em>blue</em>.</p>

CC BY-SA 4.0
2023-09-17T07:25:26.540Z
Actually, I have to explain this to 6th graders and I wasn't exactly able to understand how to explain this to them, since, I myself was a bit perplexed by reading the info. available on the internet.
Dhruv Nayak
CC BY-SA 4.0
2023-09-17T07:49:24.060Z
Hope it helped you
Arjun
CC BY-SA 4.0
2023-09-17T13:38:16.867Z
*"Rayleigh scattering absorbs only few nms, like around 30-40 nm"* What does that mean?
PM 2Ring
CC BY-SA 4.0
2023-09-17T16:18:54.840Z
It is [a continuous "stretched out" function](https://en.wikipedia.org/wiki/File:Rayleigh_sunlight_scattering.svg), not narrow. Related to the slope of it?
Peter Mortensen
CC BY-SA 4.0
2023-09-18T10:59:25.853Z
Atmosphere does not have anything to do with sun looking yellow and not green. Objects of the same temperature viewed up close will also look white and not green. Even if the spectrum peaks at that wavelength, that is just a small fraction of the spectrum so all together it adds up to white.
Tomáš Zato
CC BY-SA 4.0
2023-09-17T06:43:21.547Z
2023-09-19T10:19:34.187Z
2023-09-19T10:19:34.187Z
Arjun
<h2>A convenient pattern</h2>
<p>Uranus’ color is somewhere between green and blue. Since a lot of space trivia is in the purview of elementary education, and since patterns are useful for memorizing, it’s convenient to fudge color names to fit the pattern:</p>
<ul>
<li>Mars is <strong>red</strong>.</li>
<li>Jupiter is <strong>orange</strong>*.</li>
<li>Saturn is <strong>yellow</strong>.</li>
<li>Uranus is <strong>green</strong>.</li>
<li>Neptune is <strong>blue</strong>.</li>
</ul>
<p>*If you squint, red + yellow = orange, and brown is a dark shade of orange. Again, fudging. <a href="https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-jupiter-58.html" rel="noreferrer">“thick red, brown, yellow and white clouds“</a>. <a href="https://coolcosmos.ipac.caltech.edu/ask/104-What-color-is-Jupiter-" rel="noreferrer">“shades of white, orange, brown and red”</a>. <a href="https://howthingsfly.si.edu/ask-an-explainer/what-gives-jupiter-its-color" rel="noreferrer">“shades of white, orange, brown, and red”</a>.</p>

CC BY-SA 4.0
2023-09-18T04:49:22.637Z
Jupiter is not orange!
Mike G
CC BY-SA 4.0
2023-09-18T05:41:08.340Z
Added footnote for orange Jupiter.
Spencer Joplin
CC BY-SA 4.0
2023-09-18T10:58:40.007Z
@MikeG how can you say that! I ate Jupiter only yesterday, and the citrussey zest I experienced could not possibly have arisen if it were anything else but orange.
leftaroundabout
CC BY-SA 4.0
2023-09-18T17:40:52.137Z
@leftaroundabout So that's why I couldn't see it this morning. Before that, it was white with brown stripes.
Mike G
CC BY-SA 4.0
2023-09-18T17:44:22.050Z
@MikeG yeah, about time somebody ate it lest it rot down completely.
leftaroundabout
CC BY-SA 4.0
2023-09-18T18:48:30.507Z
Venus is white, and Mercury is black  (or at least very dark grey)
James K
CC BY-SA 4.0
2023-09-18T23:57:49.737Z
Ah, so *that's* why Pluto was delisted as a planet: [It breaks the pattern](https://solarsystem.nasa.gov/resources/933/true-colors-of-pluto/) by not being indigo or purple.
dan04
CC BY-SA 4.0
2023-09-25T12:55:20.900Z
Then Earth is not a planet either. Should have been lavender/magenta.
Oscar Lanzi
CC BY-SA 4.0
2023-09-17T23:10:51.177Z
2023-09-18T05:39:26.013Z
2023-09-18T05:39:26.013Z
Spencer Joplin
<p>Although both Uranus and Neptune exhibit a color palette ranging from deep blue to pale green, there is a prime difference in the atmospheric composition which determines the color difference.</p>
<p>In the outer layers of the atmosphere, Uranus has other hydrocarbons which are heavier than methane, mainly ethane and acetylene. These substances form tiny crystals that hang in the atmosphere which causes formation of fog and it lets through waves of different wavelengths with different efficiency and it is the deep blue color that is absorbed more efficiently and leaving behind a pale-green color which we perceive. Moreover, the atmosphere of Uranus is calmer than Neptune. So, this fog is not being torn into separate bands of clouds and hence it covers the entire planet more or less evenly.</p>
<p>On the other hand, Neptune also has such a layer of fog but it is much thinner and cannot obscure the blue color properly as there is not enough fog to absorb it.</p>
<p><a href="https://i.sstatic.net/BjQzX.jpg" rel="noreferrer"><img src="https://i.sstatic.net/BjQzX.jpg" alt="enter image description here" /></a></p>
<p><strong>Source</strong>: <a href="https://universemagazine.com/en/green-planet-for-the-green-holiday/" rel="noreferrer">https://universemagazine.com/en/green-planet-for-the-green-holiday/</a></p>

CC BY-SA 4.0
2023-09-24T07:32:51.507Z
Follow up question: https://astronomy.stackexchange.com/questions/54821/why-are-heavier-hydrocarbons-not-present-in-lower-part-of-uranian-atmosphere
Nilay Ghosh
CC BY-SA 4.0
2023-09-19T10:18:39.800Z
2023-09-19T10:18:39.800Z
Nilay Ghosh
<p>Uranus is called a <strong>green planet</strong>, although it appears blue in many of the photographs including those taken by spacecraft, like <em><a href="https://en.wikipedia.org/wiki/Voyager_2" rel="noreferrer">Voyager 2</a></em>, <em><a href="https://en.wikipedia.org/wiki/Hubble_Space_Telescope" rel="noreferrer">Hubble</a></em>, and <em><a href="https://en.wikipedia.org/wiki/James_Webb_Space_Telescope" rel="noreferrer">JWST</a></em>. NASA's <em><a href="https://solarsystem.nasa.gov/planets/uranus/in-depth/#:%7E:text=Uranus%20gets%20its%20blue%2Dgreen,in%20a%20blue%2Dgreen%20color." rel="noreferrer">Uranus</a></em> page mentions it to be <strong>bluish-green.</strong></p>
<p>One of the reasons mentioned is <strong>due to the presence of <a href="https://en.wikipedia.org/wiki/Methane" rel="noreferrer">methane</a> in the atmosphere of Uranus</strong>. But if that's the case, why can't we see this green color in the photos? I am unable to exactly grasp the mechanism behind the green color.</p>

CC BY-SA 4.0
2023-09-17T20:35:27.057Z
Those photos you linked look green to me. I imagine you are like other people I have met who label all of the in-betweeny colours beweteen blue and green as blue. If you want to explain this to your 6th graders get a high quality gradient print out between 500nm and 450nm so the range is greatly expanded and ask the different students to point to where they think blue stops and green begins.
DKNguyen
CC BY-SA 4.0
2023-09-18T02:42:44.483Z
Who calls Uranus a Green Planet?
Nacht
CC BY-SA 4.0
2023-09-18T11:15:24.140Z
Related: ["Why does moonlight have a lower color temperature?" on Physics.SE](https://physics.stackexchange.com/questions/244922/why-does-moonlight-have-a-lower-color-temperature/244984#244984)
leftaroundabout
CC BY-SA 4.0
2023-09-18T11:48:36.213Z
blue and green are not very distinctive due to the closeness of the wavelengths, so the definition varies and [many languages don't even differentiate them](https://en.wikipedia.org/wiki/Blue%E2%80%93green_distinction_in_language)
phuclv
CC BY-SA 4.0
2023-09-18T12:17:15.943Z
Some photos like [this one from Voyager 2](https://commons.wikimedia.org/wiki/File:Uranus%27_Satellite_1986_U10_Discovery_Image.jpg) are definitely green. But I don't know if it is meant to be a true colour representation or not.
curiousdannii
CC BY-SA 4.0
2023-09-18T14:46:49.933Z
There are pics from Voyager 2 showing that its blue in color. Basically that kinda created a ruckus at my end 
Dhruv Nayak
CC BY-SA 4.0
2023-09-18T15:26:52.287Z
Paging Ludwig Wittgenstein, paging Ludwig Wittgenstein...
Jon Custer
CC BY-SA 4.0
2023-09-18T23:04:28.120Z
Of the 3 first links I could  only find a picture of Uranus in the first link: https://en.m.wikipedia.org/wiki/Voyager_2#/media/File%3AUranus_as_seen_by_NASA's_Voyager_2_(remastered).png
Constantthin
CC BY-SA 4.0
2023-09-19T06:33:47.080Z
There is a also the possibility that you have some form of color vision deficiency, I'm saying that as a person with mild red-green deficiency and I perceive it as blue in many pictures, or at least turquoise.
Viktor Mellgren
CC BY-SA 4.0
2024-01-03T05:08:01.423Z
Related: https://astronomy.stackexchange.com/questions/48384/why-is-neptune-a-darker-blue-than-uranus?rq=1
Nilay Ghosh
<planetary-atmosphere><planetary-science><uranus>
Why is Uranus called a "green planet"?
Dhruv Nayak
# Why is Uranus called a "green planet"?

(Asked by: username_0 on 2023-09-17)

Uranus is called a **green planet**, although it appears blue in many of the photographs including those taken by spacecraft, like *[Voyager 2](https://en.wikipedia.org/wiki/Voyager_2)*, *[Hubble](https://en.wikipedia.org/wiki/Hubble_Space_Telescope)*, and *[JWST](https://en.wikipedia.org/wiki/James_Webb_Space_Telescope)*. NASA's *[Uranus](https://solarsystem.nasa.gov/planets/uranus/in-depth/#:%7E:text=Uranus%20gets%20its%20blue%2Dgreen,in%20a%20blue%2Dgreen%20color.)* page mentions it to be **bluish-green.**

One of the reasons mentioned is **due to the presence of [methane](https://en.wikipedia.org/wiki/Methane) in the atmosphere of Uranus**. But if that's the case, why can't we see this green color in the photos? I am unable to exactly grasp the mechanism behind the green color.

**Tags:** planetary-atmosphere, planetary-science, uranus
> **Comments:**
> **username_1**: Those photos you linked look green to me. I imagine you are like other people I have met who label all of the in-betweeny colours beweteen blue and green as blue. If you want to explain this to your 6th graders get a high quality gradient print out between 500nm and 450nm so the range is greatly expanded and ask the different students to point to where they think blue stops and green begins.  
> **username_2**: Who calls Uranus a Green Planet?  
> **username_3**: Related: ["Why does moonlight have a lower color temperature?" on Physics.SE](https://physics.stackexchange.com/questions/244922/why-does-moonlight-have-a-lower-color-temperature/244984#244984)  
> **username_4**: blue and green are not very distinctive due to the closeness of the wavelengths, so the definition varies and [many languages don't even differentiate them](https://en.wikipedia.org/wiki/Blue%E2%80%93green_distinction_in_language)  
> **username_5**: Some photos like [this one from Voyager 2](https://commons.wikimedia.org/wiki/File:Uranus%27_Satellite_1986_U10_Discovery_Image.jpg) are definitely green. But I don't know if it is meant to be a true colour representation or not.  
> **username_0**: There are pics from Voyager 2 showing that its blue in color. Basically that kinda created a ruckus at my end   
> **username_6**: Paging Ludwig Wittgenstein, paging Ludwig Wittgenstein...  
> **username_7**: Of the 3 first links I could  only find a picture of Uranus in the first link: https://en.m.wikipedia.org/wiki/Voyager_2#/media/File%3AUranus_as_seen_by_NASA's_Voyager_2_(remastered).png  
> **username_8**: There is a also the possibility that you have some form of color vision deficiency, I'm saying that as a person with mild red-green deficiency and I perceive it as blue in many pictures, or at least turquoise.  
> **username_9**: Related: https://astronomy.stackexchange.com/questions/48384/why-is-neptune-a-darker-blue-than-uranus?rq=1  

---

## 5 answers

### Answer by username_10 on 2023-09-17. Score: 44

I think your issue is linguistic not astronomical. The way a language cuts up the space of colours into discrete names is varies strongly from one language to another, and even from one dialect to another. Translating colour names is fraught with difficulty.

Uranus has a colour that is approximated by an RGB value with approximately equal amounts of green and blue (I've found the value #B2D6DB, but monitors vary, so this isn't absolute). You might describe this as "light green-blue" or "light blue-green" or "pale teal" or "pale aqua" or "duck-egg", or some form of "turquoise".

However, the usual contrast in terms of colour is with Neptune, which much closer to an azure or cerulean blue. Uranus may not be "green", but it is "greener than Neptune".

The images below show the RGB value and a [colour photo of Uranus by an Earth based observer](https://www.planetary.org/space-images/uranus-on-september-20-2015) which shows a turquoise colour

[![enter image description here](https://i.sstatic.net/hGHLUm.png)](https://i.sstatic.net/hGHLUm.png)[![enter image description here](https://i.sstatic.net/dICV7.png)](https://i.sstatic.net/dICV7.png)

> **Comments:**
> **username_11**: (+1) Nice answer!, I also faced the same problem while comparing the wavelength to the color, I couldn't find a color for the peak wavelength  
> **username_0**: Thats nice. Got much clarity regarding this issue. Thank you :)  
> **username_0**: Actually, I have to explain this to 6th graders and I wasn't exactly able to understand how to explain this to them, since, I myself was a bit perplexed by reading the info. available on the internet.  
> **username_12**: Related article to differentiating between green/blue: https://www.nature.com/articles/s41599-019-0341-7 and https://onlinelibrary.wiley.com/doi/full/10.1111/ssqu.13074  
> **username_10**: @samcarter your second link is irrelevant as it is about perceoptions of "Green spaces" ie opinions about parks and gardens; not about colour.  
> **username_13**: The image is cropped from four - each of them shows the same basic color, even the infrared ones. This one is called "straight RGB" but no information is given about color correction, white balance, etc. There's no reason to believe this one has any bearing on the "true color" of the light, which is a murky concept at best to begin with (cf. [Billmeyer and Saltzman's Principles of Color Technology](https://onlinelibrary.wiley.com/doi/book/10.1002/9781119367314) 3rd/4th edition) The image's color has been process SEVERAL times, for "internet color" possibly for your device's screen's pallet.  
> **username_13**: to even begin to get "the color of Neptune" it will take either a proper RGB recording through a good quality Bayer filter followed by fastidious color correction for the camera's own bias, or better yet, staring from a recorded, calibrated photometric spectrum, then apply the proper projection on to RGB space. *Good luck!*  See for example [this answer to *Need help simulating solar limb darkening*](https://space.stackexchange.com/a/16639/12102)  
> **username_14**: "Translating colour names is fraught with difficulty." - **So is specifying colours objectively**. Monitor RGB values simply won't do it, for a [large number of reasons](https://poynton.ca/ColorFAQ.html). Better to speak in terms of the spectrum that is actually reflected from the planet's surface (intensity at each wavelength), either with or without the filtering of Earth's atmosphere.  
> **username_10**: @KarlKnechtel I agree completely.  ..."colours are hard"... But working with spectra is well beyond what is needed to explain this to a bunch of sixth grade kids.  All you need is "It looks greeny-blue.  More green than Neptune (because of the methane)"  In this sense #B2D6DB is a "lie to children".  
> **username_15**: Specifying or reproducing colors is immensely complicated, but you don't really need an objective definition of what exact shades qualify as "green" here. If you show someone pictures of Neptune and Uranus taken with similar processing, as long as it's reasonably accurate, and say "the green one", it'll be immediately obvious which one is meant. It's not really an attempt to describe the precise color.  
> **username_16**: Color names being cultural is indeed an interesting problem (btw for me the included picture seems a lot closer to green than to blue). There is an interesting myth about people in ancient times not being able to perceive the color blue, because in the oldest ancient Greek texts don't mention the color blue, and many things we consider to be blue (the sky, or the ocean) are described by other means. However, it is most likely cultural, as for example what we call "white wine" does not look like milk, so why call it white? And the skin color of what we call white people is also not like milk.  
> **username_12**: @JamesK Oh, sorry! I must have mixed up the links when copying them into the comments. Sorry for the confusion!  
> **username_13**: @JamesK why are the other infrared images that you cropped away from this one also the same color? https://i.sstatic.net/Fon8j.jpg Don't you think it's much more likely that the author chose a color they liked and made all four the some color using artistic license? In which case isn't this answer of zero scientific value and quite misleading? Of course to some that doesn't matter as long as those reputation points keep rolling in but YOU SHOULD HAVE SHOWN THE OTHER THREE IMAGES rather than crop them out so folks have a better idea what this one is or isn't in terms of color representation  
> **username_10**: I don't know why you're getting angry.  Its an IR filter, to bring out clouds, and not a infrared image (in the way that JWST are infrared.  I cropped so it would fit on a screen better, the original is linked.  As of "of zero scientific value", you are just ranting at this point. and the shouting doesn't help.  
> **username_17**: Assuming the RGB given is the whole story (despite some comments to the contrary), it's also almost as red, so one could make a case for calling it _grey_.  
> **username_18**: the primary colors of paint (reflect light) are red yellow and blue; the primary colors of light (emitting) are red green and blue; the other colors are composed from these; so equal amounts of red and green, with less or zero blue, is yellow; equal amounts of green and blue, with less or zero red, is **cyan** or turquoise, the color of Uranus; equal amounts of red and blue, with less or zero green, is magenta (pink)  
> **username_19**: A point that might be relevant to the discussion: many cultures don't really have much of a clear separation between green and blue, which are often considered varying shades of some underlying unified color. Even in Japanese and Chinese, two quite significant cultures, has this been true historically (Japanese "ao"/"aoi" and Chinese "qīng", both meaning either "blue" or "green" depending on context).  

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### Answer by username_20 on 2023-09-17. Score: 18

This answer looks into why Uranus is "green" *or at least **greener*** compared with Neptune's blue.

Both planets have similar atmospheric compositions and would ordinarily be expected to show similar colors. But according to a [study by the National Science Foundation's NOIRLab program](https://noirlab.edu/public/news/noirlab2211/), the greater atmospheric activity of Neptune's atmosphere tends to break up the smog of more complex hydrocarbons which, on Uranus, tends to make the externally observed color of Uranus whiter and greener than the methane would otherwise be expected to give. The technical reference is from [Irwin et al.[1](https://i.sstatic.net/TPjKx.png)](<https://doi.org/10.1029/2022JE007189>), and is open access. The figure below, taken from this reference, shows the brighter transmission in Neptune at blue and violet wavelengths compared with Uranus, whereas Uranus becomes slightly brighter at longer wavelengths and less blue/violet selective overall.

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

We actually see a similar effect on Earth. In [this question](https://earthscience.stackexchange.com/questions/24623/why-does-earths-atmosphere-have-a-whiter-color-near-the-horizon) the whitening of the sky near the horizon is discussed in terms of increased Rayleigh scattering, which would be caused by the smoggy conditions on Uranus too. One answer demonstrates through photography that the sky hue on Earth also tends to become greener as it becomes whiter, matching well with the difference between Uranus and Neptune.

**Reference** (open access)

1. Irwin, P. G. J., Teanby, N. A., Fletcher, L. N., Toledo, D., Orton, G. S., Wong, M. H., et al. (2022). "Hazy blue worlds: A holistic aerosol model for Uranus and Neptune, including dark spots". *Journal of Geophysical Research: Planets*, **127**, e2022JE007189. <https://doi.org/10.1029/2022JE007189>

> **Comments:**
> **username_21**: It's amazing that the spectra of Neptune and Uranus are almost identical!  

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### Answer by username_11 on 2023-09-17. Score: 9

This is just a mere illusion. In reality, the peak wavelength is actually between green and blue, that is slightly cyanish/turquoise. The reason this happens is because the atmosphere of Uranus contains methane, which has an absorption wavelength between yellow to red leading to blue/green reflected wavelength. In the albedo of 30% of the sunlight reflected by Uranus, blue green light is absorbed the most.

This wavelength is however scattered in our atmosphere, via atmosphere refraction, specifically [Rayleigh scattering](https://en.wikipedia.org/wiki/Rayleigh_scattering#From_molecules) which leads to telluric absorption which leads to a few wavelengths being scattered more like blue wavelengths, which is precisely observed in the ground-based telescope images. In space-based telescopes where there is nill telluric scattering, the actual color is perceived.

Even though the green color is more sensitive to our light cones, green light is already absorbed by our atmosphere, before reaching our eye.

This is quite similar to how the Sun's peak wavelength is green, but we perceive it as yellow, except the atmospheric refraction is different in this case.

Space telescope:

[![Enter image description here](https://i.sstatic.net/Y52h6.png)](https://i.sstatic.net/Y52h6.png)

vs.

Ground-based telescope:

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

It's not leaned towards pure green or pure blue. The Rayleigh scattering absorbs only few nms, like around 30-40 nm.

In conclusion:

This is a mere mirage by the atmospheric scattering of the Earth, aerosols like to absorb more green than blue due to their electrons and quantum mechanics even though Uranus is lying between *green* and *blue*.

> **Comments:**
> **username_0**: Actually, I have to explain this to 6th graders and I wasn't exactly able to understand how to explain this to them, since, I myself was a bit perplexed by reading the info. available on the internet.  
> **username_11**: Hope it helped you  
> **username_22**: *"Rayleigh scattering absorbs only few nms, like around 30-40 nm"* What does that mean?  
> **username_23**: It is [a continuous "stretched out" function](https://en.wikipedia.org/wiki/File:Rayleigh_sunlight_scattering.svg), not narrow. Related to the slope of it?  
> **username_24**: Atmosphere does not have anything to do with sun looking yellow and not green. Objects of the same temperature viewed up close will also look white and not green. Even if the spectrum peaks at that wavelength, that is just a small fraction of the spectrum so all together it adds up to white.  

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### Answer by username_25 on 2023-09-17. Score: 7

## A convenient pattern

Uranus’ color is somewhere between green and blue. Since a lot of space trivia is in the purview of elementary education, and since patterns are useful for memorizing, it’s convenient to fudge color names to fit the pattern:

* Mars is **red**.
* Jupiter is **orange**\*.
* Saturn is **yellow**.
* Uranus is **green**.
* Neptune is **blue**.

\*If you squint, red + yellow = orange, and brown is a dark shade of orange. Again, fudging. [“thick red, brown, yellow and white clouds“](https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-jupiter-58.html). [“shades of white, orange, brown and red”](https://coolcosmos.ipac.caltech.edu/ask/104-What-color-is-Jupiter-). [“shades of white, orange, brown, and red”](https://howthingsfly.si.edu/ask-an-explainer/what-gives-jupiter-its-color).

> **Comments:**
> **username_26**: Jupiter is not orange!  
> **username_25**: Added footnote for orange Jupiter.  
> **username_3**: @MikeG how can you say that! I ate Jupiter only yesterday, and the citrussey zest I experienced could not possibly have arisen if it were anything else but orange.  
> **username_26**: @leftaroundabout So that's why I couldn't see it this morning. Before that, it was white with brown stripes.  
> **username_3**: @MikeG yeah, about time somebody ate it lest it rot down completely.  
> **username_10**: Venus is white, and Mercury is black  (or at least very dark grey)  
> **username_27**: Ah, so *that's* why Pluto was delisted as a planet: [It breaks the pattern](https://solarsystem.nasa.gov/resources/933/true-colors-of-pluto/) by not being indigo or purple.  
> **username_20**: Then Earth is not a planet either. Should have been lavender/magenta.  

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### Answer by username_9 on 2023-09-19. Score: 6

Although both Uranus and Neptune exhibit a color palette ranging from deep blue to pale green, there is a prime difference in the atmospheric composition which determines the color difference.

In the outer layers of the atmosphere, Uranus has other hydrocarbons which are heavier than methane, mainly ethane and acetylene. These substances form tiny crystals that hang in the atmosphere which causes formation of fog and it lets through waves of different wavelengths with different efficiency and it is the deep blue color that is absorbed more efficiently and leaving behind a pale-green color which we perceive. Moreover, the atmosphere of Uranus is calmer than Neptune. So, this fog is not being torn into separate bands of clouds and hence it covers the entire planet more or less evenly.

On the other hand, Neptune also has such a layer of fog but it is much thinner and cannot obscure the blue color properly as there is not enough fog to absorb it.

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

**Source**: <https://universemagazine.com/en/green-planet-for-the-green-holiday/>

> **Comments:**
> **username_9**: Follow up question: https://astronomy.stackexchange.com/questions/54821/why-are-heavier-hydrocarbons-not-present-in-lower-part-of-uranian-atmosphere  

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