# Why is the sun yellow? **URL:** \ **Category:** Factual Questions\ **Created:** [October 13, 2010, 9:23am UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976 "2010-10-13T09:23:41Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [October 14, 2010, 9:30am UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/21 "2010-10-14T09:30:16Z")
When an astronomical image is taken in multiple wavelengths, the usual convention is that the shortest wavelength is rendered in blue, the next shortest in green and the longest in red. I’m not sure what they do for 4-wavelength images, but I expect the second longest would be in yellow. In practice, this may mean that an actual red or yellow is rendered blue and two IR wavelengths are in green and red. As for artificial light, the temperature of an incandescent light filament is somewhere around 3000 K (give or take a few hundred depending on wattage), so those are definitely yellower than the Sun. Fluorescent tubes are usually rated by their equivalent blackbody temp on the package. They range from about 3500 K to 5500 K or so. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 14, 2010, 11:53am UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/22 "2010-10-14T11:53:55Z")
We covered this earlier this year: [http://boards.straightdope.com/sdmb/showthread.php?t=550260&highlight=yellow+sunlight+scattering](http://boards.straightdope.com/sdmb/showthread.php?t=550260&highlight=yellow+sunlight+scattering) As I stated there, I strongly suspect the reason that we perceive the sun as yellow is that, as the sun descends and atmospheric scattering starts to shift its color towards the red you see when the sun is at the horizon, the sun begins to color yellow and stays that way for most of its descent. Sometimes it never does go to orange or red at the horizon, but stays at yellow all the way down, evidently depending on the amount of scattering material in the atmosphere (although the air molecules themselves will cause the 1/(wavelength) ^4 scattering). I’ve done an extensive search on this, and haven’t found any definitive studies on the topic. The closest I found is a brief treatment by Phil Plaitt, The Bad Astronomer, in his first book. In this, he frankly says that he doesn’t know. I seriously doubt that the sun is viewed as yellow “by contrast with” the blue sky. There is a connection, because the atmospheric scatter does extract blue from the white sunlight, leaving yellow, but it’s not the contrast with blue – if you allow sunlight directly into a room near sunset and let it fall on a white surface, the light appears yellow, even though there’s no blue sky around it. It’s not simply a “convention”, either, since “yellow sun” is a pretty universal given all over the world. I wrote an article about this, by the way, for _Optics and Photonics News_ last year. It’s online. I’d link to it, but you have to be an OSA member to open it. ---
**Author:** ![ramel](https://avatars.discourse-cdn.com/v4/letter/r/eb8c5e/32.png) [@ramel](https://boards.straightdope.com/u/ramel)\ **Post date:** [October 14, 2010, 12:16pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/23 "2010-10-14T12:16:41Z")
The sun is white. It appears yellow because some of the blue in the white light gets scattered out of it by the atmosphere. That makes the sky blue and the sun appear yellow. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 14, 2010, 12:32pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/24 "2010-10-14T12:32:51Z")
> [@](#): > > It appears yellow because some of the blue in the white light gets scattered out of it by the atmosphere. During most of the day the scattering is insufficient to change the color of the sun – you can’t explain the apparent yellowness of the sun by appealing directly to Rayleigh scatter. Besides, as Plaitt points out, if the sun really had so much light scattered out that it appeared yellow, then the clouds would be yellow, as well. The whiteness of clouds also argues against the idea that “the sun is yellow by contrast with the blue sky”. If contrast with the blue sky made white things appear yellow, then clouds would be yellow, too. They aren’t. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 14, 2010, 12:54pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/25 "2010-10-14T12:54:44Z")
Link [http://www.osa-opn.org/Content/ViewFile.aspx?id=11147](http://www.osa-opn.org/Content/ViewFile.aspx?id=11147) I’m not sure if you can open it without OSA ID, but this is as its cited in the Wikipedia article on the sun. > **[Sun](https://en.wikipedia.org/wiki/Sun)** > > The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radiation, and is the most important source of energy for life on Earth. > The Sun's radius is about 695,000 kilometers (432,000 miles), or 109 times that of Earth. Its mass is about 330,000 times that of Earth, comprising about 99.86% of the total mass of the S... ---
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [October 14, 2010, 1:28pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/26 "2010-10-14T13:28:39Z")
> [@falcotron](#): > > First, if it’s a convention, it seems to be universal. It’s not just modern American kids who draw the sun yellow. Professional artists in every culture throughout time have drawn it that way. Cultures ranging from the Mongols to the Babylonians to the Romans to the Aztecs used a yellow sun as a religious symbol. Sure, but some conventions are universal. What percentage of a head does the face cover? What color is fire? What color are tree trunks? Most of humanity gets these wrong, too. ---
**Author:** ![ethansiegel](https://avatars.discourse-cdn.com/v4/letter/e/2bfe46/32.png) [@ethansiegel](https://boards.straightdope.com/u/ethansiegel)\ **Post date:** [October 14, 2010, 2:56pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/27 "2010-10-14T14:56:04Z")
> [@falcotron](#): > > ethansiegel, thanks for replying to my second question–but I think you were actually answering the first one instead. > > You gave lots of good info on the first question (the point about the double-reflected sun is what suddenly made it click in my head), but nothing for the second one. > > This is probably my fault for asking two questions in the same thread, and being so long-winded about it. (Also, maybe I should have used nm instead of Å–if someone isn’t seeing Unicode properly they’d think I was giving temperatures instead of wavelengths.) > > And I’m guessing you actually know the answer to my second question, too. So, let me try again. > > The sun’s surface is somewhere around 5700K. It should peak at 508.9nm, which is yellowish. But it actually peaks at 480nm, which is bluish-green. Why? > > Every page I found that gives the sun’s peak says it’s 480nm, and every graph (e.g., [http://zebu.uoregon.edu/~imamura/122/images/solar\_spectrum.png](http://zebu.uoregon.edu/~imamura/122/images/solar_spectrum.png)) agrees. Every page that I found gives a different temperature for the surface of the sun, but none of them are nearly hot enough to give a 480nm peak. > > [Sunlight - Wikipedia](http://en.wikipedia.org/wiki/Sunlight) says “The spectrum of the Sun’s solar radiation is close to that of a black body with a temperature of about 5,800 K”–but it then gives a copy of that same image from above, which shows it peaking like a body well over 6000K. > > The closest thing I found to an explanation is at [Phil Plait's Bad Astronomy: Misconceptions](http://www.badastronomy.com/bad/misc/starcolors.html) says “The Sun, for example, should peak at about 5000 Angstroms or so, having a surface temperature of 5500 K. However, due to complicated processes, it actually peaks bluer than that, around 4800 Angstroms.” So, what are those “complicated processes”? > > I’m assuming that 480nm is measured from space (or compensates for scattering); otherwise, the problem is even worse. Falcotron, you’re actually looking at it from a more sophisticated point of view than I realized; sorry for that. There’s a big difference between an ideal blackbody and a real blackbody. (I mean where “big” is from the point of view of a quantitative scientist.) We can measure how the Sun deviates from Wein’s law, and we find out that it has more yellow-red and violet-blue light, and slightly less green light than an ideal blackbody would. (See the first graph here: [Black Body Radiation](http://cseligman.com/text/sun/blackbody.htm) ) If you’re asking what processes _cause_ the light to deviate from blackbody in the way that they do, I can easily explain the absorption lines, but, like all the other astronomers you cite, I can only give you my best guess as to why the spectrum looks like it does, not a definitive scientific conclusion. If you want my best guess, it’d have to do with the fact that the Sunlight we see comes from ultra-high energy photons created at the core of the Sun needing to reach the surface, and taking anywhere from about 10,000 to 170,000 years to do it, and the respective number of collisions with atoms that result from that. The ones that take less time, obviously, will have (on average) higher energies, and the ones that take longer will have lower energies, and my hunch is that produces the “real” blackbody we see (more blue, more red, less green) over the ideal blackbody that a uniform-temperature radiator will produce. (And if you think the Sun really is a uniform temperature, you should check out a sunspot.) And – although I hope this answers your question as best as I’m able – I’m surprised nobody linked to the image of the Planckian Locus in chromaticity space: [File:PlanckianLocus.png - Wikipedia](http://en.wikipedia.org/wiki/File:PlanckianLocus.png) Where is the Sun, a real blackbody, relative to the Planckian Locus (for ideal blackbodies)? I’d be curious to know, too! ---
**Author:** ![ethansiegel](https://avatars.discourse-cdn.com/v4/letter/e/2bfe46/32.png) [@ethansiegel](https://boards.straightdope.com/u/ethansiegel)\ **Post date:** [October 14, 2010, 2:58pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/28 "2010-10-14T14:58:49Z")
> [@Martian Bigfoot](#): > > What about astronomical images like [this](http://en.wikipedia.org/wiki/File:The_Sun_by_the_Atmospheric_Imaging_Assembly_of_NASA%27s_Solar_Dynamics_Observatory_-_20100801.jpg), where the sun photographed from space always looks yellow or orange? Actually, I think that image is actually ultraviolet or x-ray, so I suppose the colors aren’t real. Are they made to look like that just because of convention? I recognize that photo! That photo is from the Solar Dynamics Observatory! That one is, in fact, taken in the X-ray and false-colored. ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [October 14, 2010, 3:01pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/29 "2010-10-14T15:01:51Z")
> [@Chronos](#): > > **FluffyBob** has it: The Sun is white. I think the only reason we think of it as yellow is by contrast with the blue sky. Wrong. [The sun’s not yellow it’s chicken.](http://www.bobdylan.com/#/songs/tombstone-blues) ---
**Author:** ![falcotron](https://avatars.discourse-cdn.com/v4/letter/f/3ab097/32.png) [@falcotron](https://boards.straightdope.com/u/falcotron)\ **Post date:** [October 14, 2010, 4:26pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/30 "2010-10-14T16:26:20Z")
> [@ethansiegel](#): > > Falcotron, you’re actually looking at it from a more sophisticated point of view than I realized; sorry for that. Well, it’s not so much that, as that I asked two separate questions that didn’t really look like two separate questions, so it’s my fault. Once I realized that, I reposted the second question in a separate thread ([Why does the sun's spectrum peak at 480nm? - Factual Questions - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=581781)), which of course just makes things even more confusing, as there are now answers in two places. Anyway, I now understand that (a) it’s not just a shifted blackbody spectrum, it’s completely off, and (b) the reason sites like Phil Plaitt’s just say things like “complicated processes” has nothing to do with not wanting to bother explaining it to laymen, but rather nobody knowing the answer. But your hunch is interesting. I was thinking that it must have something to do with all that solar atmosphere above the surface of last scattering that defines the blackbody within the sun, but you’re saying it’s not even close to a blackbody at that layer, because of different travel times from the interior. That’s something we should be able to test just by watching the sun carefully for 170000 years as it starts to turn red in a few billion years, right? I was kind of hoping for an answer sooner than that, but I’m patient. ---
**Author:** ![falcotron](https://avatars.discourse-cdn.com/v4/letter/f/3ab097/32.png) [@falcotron](https://boards.straightdope.com/u/falcotron)\ **Post date:** [October 14, 2010, 4:55pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/31 "2010-10-14T16:55:13Z")
> [@CalMeacham](#): > > During most of the day the scattering is insufficient to change the color of the sun – you can’t explain the apparent yellowness of the sun by appealing directly to Rayleigh scatter. Besides, as Plaitt points out, if the sun really had so much light scattered out that it appeared yellow, then the clouds would be yellow, as well. > > The whiteness of clouds also argues against the idea that “the sun is yellow by contrast with the blue sky”. If contrast with the blue sky made white things appear yellow, then clouds would be yellow, too. They aren’t. Damn. Everyone had me so convinced that it was either scattering, or scattering plus a bit of contrast. The clouds definitely blow the contrast theory out of the water. But I’m not 100% convinced about scattering. Clouds don’t just reflect the yellow direct sunlight; they also reflect the blue scattered sunlight from the sky, right? Maybe there’s too little of this to make a difference (how much of the ambient light is direct, and how much scattered, anyway?), but I’d guess that (especially if you’re looking at clouds from underneath, as we usually are) there could be enough to have some contribution. Also, don’t clouds do some scattering themselves? I vaguely remember something about water droplets being so close to the wavelength of visible light that Rayleigh scattering doesn’t apply, but clouds are chock full of other molecules of the appropriate sizes in suspension, just like air. (In fact, IIRC, sulfates scatter so much better than most other particles in the air that skies are noticeably blur when sulfate levels are high, and sulfates can concentrate in clouds.) Anyway, I’m off to go read the other thread you linked to before I toss out even more ideas that have already been shot down. 🙂 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 14, 2010, 4:59pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/32 "2010-10-14T16:59:07Z")
> [@](#): > > The whiteness of clouds also argues against the idea that “the sun is yellow by contrast with the blue sky”. If contrast with the blue sky made white things appear yellow, then clouds would be yellow, too. They aren’t. Except that clouds are larger, in angular size, than the Sun. No point on the surface of the Sun is ever more than a quarter of a degree from sky, or maybe two or three degrees if you don’t count the glare surrounding the disk itself, so comparison with the surrounding blue is inevitable. A cloud can easily be ten or twenty, or 180, degrees across, though, so there’s much more cloud which isn’t directly adjacent to blue. ---
**Author:** ![falcotron](https://avatars.discourse-cdn.com/v4/letter/f/3ab097/32.png) [@falcotron](https://boards.straightdope.com/u/falcotron)\ **Post date:** [October 14, 2010, 5:53pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/33 "2010-10-14T17:53:00Z")
> [@CalMeacham](#): > > We covered this earlier this year: > > [http://boards.straightdope.com/sdmb/showthread.php?t=550260&highlight=yellow+sunlight+scattering](http://boards.straightdope.com/sdmb/showthread.php?t=550260&highlight=yellow+sunlight+scattering) OK, just read it. First, the discussion between you and billfish678 apparently got derailed once he got angry and a bit rude and you stopped answering him, which is a pity. I’ll try to avoid making the same mistake. 🙂 Second, your suggestion is that the sun and sunlight really are the same color all the time–but we only look at the sun when it’s more yellow, while we see ambient sunlight all day long, including when it’s white. But normally, our concepts aren’t based on averaging out perceptions like that. If we think the sun is yellower than the sunlit day, that’s most likely to be based on perceiving a contrast between the two of them at the same time. And, in fact, even in late afternoon, when we can look at the sun and see it looking yellow, the sunlit day still doesn’t look yellow to us. Finally, billfish brought up basically the same cloud explanation as me, and you replied: > [@](#): > > It you want to argue that the sun is yellow but clouds are white because Rayleigh scattering by the blue sky adds the blue back in, that woin’t wash., A white sheet of paper illuminated by sunlight let in through a window appears white, not yellow. I just tested this. Here’s the setting: My living room has 4 large windows, and it’s pretty bright. The sun is shining directly through 1 of those windows. I have no interior lights on except the MacBook I’m typing on. And I have two white bedsheets that just came out of the laundry. So, I hung one in front of the window with the sun shining in, and one in front of the window on the far end of the same wall. And I opened both windows. It’s too hard to tell whether one sheet is more yellowish than the other (although one is very clearly brighter). But what’s very easy to tell is that, in the window the sun is shining it, the brighter part near the center of the sheet is also yellower than the rest. This seems to show that: 1. My contrast idea is completely and utterly wrong, just as you argued. 2. Direct sunlight really is yellower than ambient sunlight. (Unless my sheets are fluorescing yellow or something, I can’t see what other explanation there could be.) 3. The “clouds are white because they reflect both yellow sunlight and blue sky” idea that both I and billfish suggested isn’t proven, but it’s still plausible. I think billfish’s digital camera experiment also sounds pretty interesting, but he left out something important: How did he take a picture of “direct sunlight reflected onto a white piece of paper (but not exposed to the blue of the sky)”? I can imagine ways to do it, but it would have been nice to know how he _actually_ did it. Anyway, I think the key question is, how much of the light that reaches us is scattered blue sky light? If it really is 10% or more (as billfish claims), that’s more than enough to explain why clouds are white. (The sky is a lot bluer than the sun is yellow, so it wouldn’t have to be anywhere near 50/50.) ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 14, 2010, 5:53pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/34 "2010-10-14T17:53:11Z")
> [@](#): > > Except that clouds are larger, in angular size, than the Sun. No point on the surface of the Sun is ever more than a quarter of a degree from sky, or maybe two or three degrees if you don’t count the glare surrounding the disk itself, so comparison with the surrounding blue is inevitable. A cloud can easily be ten or twenty, or 180, degrees across, though, so there’s much more cloud which isn’t directly adjacent to blue. 1.) I’ve seen plenty of small clouds 2.) The same argument works for the edges of white buildings. Or white street signs. 3.) take a mirror and reflect a portion of a white light or something toward your eye against the blue sky. It won’t look yellow. > [@](#): > > Clouds don’t just reflect the yellow direct sunlight; they also reflect the blue scattered sunlight from the sky, right? Much less than scattered out. You can’t claim that light gets scattered out, then perfectly scattered back in to perfectly correct the loss. In that case nothing would ever get colored by scattering. ---
**Author:** ![Enilno](https://avatars.discourse-cdn.com/v4/letter/e/58f4c7/32.png) [@Enilno](https://boards.straightdope.com/u/Enilno)\ **Post date:** [October 14, 2010, 5:55pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/35 "2010-10-14T17:55:59Z")
Part if it may be that most of the times when we can look at the Sun without it being too painful is during dusk and dawn, when the light has to pass through more of the atmosphere. So our mental imageof the sun is more red/yellow than it actually is. ---
**Author:** ![falcotron](https://avatars.discourse-cdn.com/v4/letter/f/3ab097/32.png) [@falcotron](https://boards.straightdope.com/u/falcotron)\ **Post date:** [October 14, 2010, 6:02pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/36 "2010-10-14T18:02:44Z")
> [@CalMeacham](#): > > > [@](#): > > > > Clouds don’t just reflect the yellow direct sunlight; they also reflect the blue scattered sunlight from the sky, right? > > Much less than scattered out. You can’t claim that light gets scattered out, then perfectly scattered back in to perfectly correct the loss. In that case nothing would ever get colored by scattering. Sure, but it doesn’t have to be anywhere near perfect. Since I don’t know the numbers, I’m going to pull some out of my ass. Let’s say that 33% of the blue light from the sun is lost to scattering. But 33% of that scattered light reaches us, and therefore becomes part of the ambient lighting. So, the direct image of the sun is missing 33% of its blue, but ambient sunlight is missing only 22% of its blue. Since ambient sunlight is what we define as white, and direct sunlight has less blue, the sun is yellow. And likewise, if 33% of that scattered light is reflected off clouds, they end up the exact same color as ambient sunlight, so they’re white. Now, if you tell me that the numbers are more like 33% and 0.001% instead of 33% and 33%, that might be a different story. But some decent amount of that scattered light must reach us, or wouldn’t the sky would look black, not blue? ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 14, 2010, 6:10pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/37 "2010-10-14T18:10:34Z")
It’s been a while since I’ve done it, but I’m pretty certain the loss is a _lot_ less than 33%, and the sun viewed directly has (for practical purposes) no blue scattered out. That’s why people like Phil Plaitt in his book say that sunlight isn’t yellow because of light scattered out of it. I’m not sure what you mean by “ambient sunlight” and “direct sunlight”, but the clouds scatter essentially direct sunlight. If there was enough scatter from the atmosphere to make direct sunlight appear yellow, then that’s the light that would hit the clouds and scatter. And, as I say, that would make the clouds appear yellow, not white. ---
**Author:** ![falcotron](https://avatars.discourse-cdn.com/v4/letter/f/3ab097/32.png) [@falcotron](https://boards.straightdope.com/u/falcotron)\ **Post date:** [October 14, 2010, 6:18pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/38 "2010-10-14T18:18:35Z")
> [@Contrapuntal](#): > > > [@Chronos](#): > > > > **FluffyBob** has it: The Sun is white. I think the only reason we think of it as yellow is by contrast with the blue sky. > > Wrong. [The sun’s not yellow it’s chicken.](http://www.bobdylan.com/#/songs/tombstone-blues) You know, my father gave the exact same answer. Since I’m as much a child of the 80s as he is a child of the 60s, I had no choice but to reply, “I learned it from you, dad! I learned it from watching you!” It took him a moment to get the sun/son reference, after which he said, “I see what you did. Bread and Circuses.” ---
**Author:** ![falcotron](https://avatars.discourse-cdn.com/v4/letter/f/3ab097/32.png) [@falcotron](https://boards.straightdope.com/u/falcotron)\ **Post date:** [October 14, 2010, 6:34pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/39 "2010-10-14T18:34:58Z")
> [@CalMeacham](#): > > I’m not sure what you mean by “ambient sunlight” and “direct sunlight” Sorry; I don’t know the right terms. By “ambient sunlight” I mean all of the light reaching our eyes on a sunny day (directly, scattered through the sky, reflected off surfaces, and anything else I’m forgetting). By “direct sunlight” I mean just the light that reaches our eyes more-or-less straight from the sun. > [@CalMeacham](#): > > but the clouds scatter essentially direct sunlight. If there was enough scatter from the atmosphere to make direct sunlight appear yellow, then that’s the light that would hit the clouds and scatter. And, as I say, that would make the clouds appear yellow, not white. So you’re saying the clouds neither reflect any significant amount of light from below, nor re-scatter any light that’s already been scattered by the air? And meanwhile, this is probably an irrelevant side question (but I’m not sure): Why doesn’t the clouds’ scattering change the color of the light that reaches us from them? Do they scatter all wavelengths equally, or happen to preferentially scatter exactly the right wavelengths? Is this related to that bit about water droplets being too close in size to visible wavelengths for Rayleigh scattering to work? ---
**Author:** ![Kinthalis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kinthalis/32/16084_2.png) [@Kinthalis](https://boards.straightdope.com/u/Kinthalis)\ **Post date:** [October 14, 2010, 7:20pm UTC](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976/40 "2010-10-14T19:20:27Z")
Ok, so does anyone actually have a regular old color photograph of the sun from space? Or are scientist always using xrays and radio waves to look at it? [Previous page](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976.md?page=1) [Next page](https://boards.straightdope.com/t/why-is-the-sun-yellow/556976.md?page=3)