<p>Every "normal" star, produces a more or less "<a href="https://en.wikipedia.org/wiki/Black-body_radiation" rel="noreferrer">black-body</a>" spectrum, at some temperature (more-or-less because there are brighter and darker lines caused by specific elements in the upper layers of the star), so there will always be a range of colours of light (or electromagnetic radiation at least) in its light, which can be spread to give a rainbow. </p>

<p>A white object (like ice crystals, or bleached cotton) reflects all colours of light more or less equally (over some range of wavelengths of interest, anyway). </p>

<p>So, if the Sun suddenly cooled, so that it was emitting a 5000K black body spectrum instead of its current 6000K, with more red light and less blue light, that change would be reflected in the light reflected from a white object, which would look more yellow or orange to our eyes. </p>

<p><a href="https://i.sstatic.net/07b4r.png" rel="noreferrer"><img src="https://i.sstatic.net/07b4r.png" alt="this chart attempts, within the limitations of the web to illustrate the colours"></a></p>

<p>There are a couple of caveats though:</p>

<ol>
<li>As @badjohn pointed out in a simultaneous answer, our brain processes visual information in odd ways. If the colour of sunlight changed, the brain might try and compensate for the overall shift and you might see everything more as you expect it, and less as it now is.</li>
<li>We evolved to perceive sunlight as white. If we had evolved around a cooler star, we would probably perceive a different colour as white.</li>
</ol>

CC BY-SA 4.0
2018-09-30T11:05:30.607Z
Walk indoors on a bright day to a room with no windows and a low power incandescent bulb.  Do you say: " Hey, my shirt looks orange, I was sure that it was white when I was outside"?  Your eyes (1) are clever enough to adjust and figure out that your shirt is still reflecting  all visible frequencies approximately equally.  (1) Well, brain actually.  Most digital cameras have automatic white balance which does something similar (optional on fancier ones).
badjohn
CC BY-SA 4.0
2018-09-30T14:23:17.907Z
Both answers were helpful :)
Antony Alexander
CC BY-SA 4.0
2018-09-30T10:47:27.530Z
2018-09-30T10:47:27.530Z
Steve Linton
<p>We see  white objects as white under a very wide range of lighting conditions.  Photography resources will be quite helpful.  Look at a white piece of paper at dawn, at noon, and under a variety of artificial light sources.  The spectrum of the light hitting your eye will vary a lot but, except in extreme cases, it will stil look white.  The answer is not in astronomy but the visual processing in our brains.</p>
<p>Some extra material.</p>
<p>As I just mentioned in a comment, digital cameras do something similar and call it automatic white balance.  Search for that and you will find loads of discussions in photography websites.</p>
<p>It fails in some extreme cases.  E.g. sodium street lamps which are close to monochromatic and a combination of UV lamps and fluorescent substances.</p>

CC BY-SA 4.0
2018-09-30T10:30:02.763Z
2024-01-25T08:03:02.503Z
2024-01-25T08:03:02.503Z
badjohn
<p>You have confused solar spectral output with our neurological processing of collected photons.  While it's true that a careful mix of red,blue, green photons may be perceived as "white" or "off-white,"  whiteness in general occurs when either (1) the cones, which discriminate on the basis of wavelength, saturate and all "output" signals are peak, or (2) the light levels are so low that only the rods, which do not discriminate by wavelength but have higher sensitivity than the cones, respond.  For example, in a dim night locale, everything is black, grey or white.  </p>

<p>It gets worse, as our brain reprocesses the incoming signals to make the colors we see "fit expectations."  That's why we tend to observe everything in our backyard garden as having the same coloration all day, but if we take a photo at sunset, the image will show a skew towards the red (due to extreme loss of blue, green thru the atmosphere).</p>

CC BY-SA 4.0
2018-10-01T18:13:55.870Z
2018-10-01T18:13:55.870Z
Carl Witthoft
<p>If the Sun was an early K or late G-type star for example, the white that we see in objects such as snow would still exist - just reflecting yellow light instead of what we are used to. If you look outside at snow in the evening, while the sun lower on the horizon and is yellowed due to Rayleigh scattering (or in other words, at about 4500K in color temperature, congruent with orange-yellow stars), the snow would still appear as white, just reflecting a bit of that color now. So no, an object's color is not directly influenced by the Sun's light. That would be like saying a piece of paper turns orange when it's under a warm lamp.</p>
<p>However, if the Sun was yellow, there would be more noticeable effects on our planet. For example, the sky might be a more pale color, as yellow stars do not contain as much blue light as white stars do, meaning the atmosphere has less of it to scatter. With that in mind, the Sun itself would also appear more orangey in our sky. Redder colors in rainbows would be more prominent, while blues would be faded. Then our planet will frost over because we're out of our habitable zone of our now cold star...</p>

CC BY-SA 4.0
2024-01-25T16:09:35.067Z
2024-01-25T16:09:35.067Z
4NT4R3S
<p>Hypothetically,if our sun was yellow would we still be able to see white colour on objects like snow,cotton etc.? Would we have the phenomenon of rainbow?</p>

CC BY-SA 4.0
2018-09-30T14:43:10.273Z
Our Sun *isn't yellow??* https://i.sstatic.net/bq60f.jpg Seriously though, I think the question is primarily opinion-based as different people in different fields will have a different working definition of what white or yellow illumination means, and what white or yellow appearance of objects means. It's a slippery-slope question unless you are in a room full of color experts with a copy of  [Billmeyer and Saltzman](https://onlinelibrary.wiley.com/doi/abs/10.1002/col.10083) handy. Color is totally subjective unless you really "go deep" collect a lot of data, and do a lot of analysis.
uhoh
CC BY-SA 4.0
2018-09-30T14:45:05.157Z
https://en.wikipedia.org/wiki/The_dress
uhoh
<star><the-sun><astrophysics>
Hypothetically, if our sun was yellow would we still see "white" colours?
Antony Alexander
# Hypothetically, if our sun was yellow would we still see "white" colours?

(Asked by: username_0 on 2018-09-30)

Hypothetically,if our sun was yellow would we still be able to see white colour on objects like snow,cotton etc.? Would we have the phenomenon of rainbow?

**Tags:** star, the-sun, astrophysics

> **Comments:**
> **username_1**: Our Sun *isn't yellow??* https://i.sstatic.net/bq60f.jpg Seriously though, I think the question is primarily opinion-based as different people in different fields will have a different working definition of what white or yellow illumination means, and what white or yellow appearance of objects means. It's a slippery-slope question unless you are in a room full of color experts with a copy of  [Billmeyer and Saltzman](https://onlinelibrary.wiley.com/doi/abs/10.1002/col.10083) handy. Color is totally subjective unless you really "go deep" collect a lot of data, and do a lot of analysis.  
> **username_1**: https://en.wikipedia.org/wiki/The_dress  

---

## 4 answers

### Answer by username_2 on 2018-09-30. Score: 5

Every "normal" star, produces a more or less "[black-body](https://en.wikipedia.org/wiki/Black-body_radiation)" spectrum, at some temperature (more-or-less because there are brighter and darker lines caused by specific elements in the upper layers of the star), so there will always be a range of colours of light (or electromagnetic radiation at least) in its light, which can be spread to give a rainbow.

A white object (like ice crystals, or bleached cotton) reflects all colours of light more or less equally (over some range of wavelengths of interest, anyway).

So, if the Sun suddenly cooled, so that it was emitting a 5000K black body spectrum instead of its current 6000K, with more red light and less blue light, that change would be reflected in the light reflected from a white object, which would look more yellow or orange to our eyes.

[![this chart attempts, within the limitations of the web to illustrate the colours](https://i.sstatic.net/07b4r.png)](https://i.sstatic.net/07b4r.png)

There are a couple of caveats though:

1. As @username_3 pointed out in a simultaneous answer, our brain processes visual information in odd ways. If the colour of sunlight changed, the brain might try and compensate for the overall shift and you might see everything more as you expect it, and less as it now is.
2. We evolved to perceive sunlight as white. If we had evolved around a cooler star, we would probably perceive a different colour as white.

> **Comments:**
> **username_3**: Walk indoors on a bright day to a room with no windows and a low power incandescent bulb.  Do you say: " Hey, my shirt looks orange, I was sure that it was white when I was outside"?  Your eyes (1) are clever enough to adjust and figure out that your shirt is still reflecting  all visible frequencies approximately equally.  (1) Well, brain actually.  Most digital cameras have automatic white balance which does something similar (optional on fancier ones).  
> **username_0**: Both answers were helpful :)  

---

### Answer by username_3 on 2018-09-30. Score: 3

We see white objects as white under a very wide range of lighting conditions. Photography resources will be quite helpful. Look at a white piece of paper at dawn, at noon, and under a variety of artificial light sources. The spectrum of the light hitting your eye will vary a lot but, except in extreme cases, it will stil look white. The answer is not in astronomy but the visual processing in our brains.

Some extra material.

As I just mentioned in a comment, digital cameras do something similar and call it automatic white balance. Search for that and you will find loads of discussions in photography websites.

It fails in some extreme cases. E.g. sodium street lamps which are close to monochromatic and a combination of UV lamps and fluorescent substances.


---

### Answer by username_4 on 2018-10-01. Score: 2

You have confused solar spectral output with our neurological processing of collected photons. While it's true that a careful mix of red,blue, green photons may be perceived as "white" or "off-white," whiteness in general occurs when either (1) the cones, which discriminate on the basis of wavelength, saturate and all "output" signals are peak, or (2) the light levels are so low that only the rods, which do not discriminate by wavelength but have higher sensitivity than the cones, respond. For example, in a dim night locale, everything is black, grey or white.

It gets worse, as our brain reprocesses the incoming signals to make the colors we see "fit expectations." That's why we tend to observe everything in our backyard garden as having the same coloration all day, but if we take a photo at sunset, the image will show a skew towards the red (due to extreme loss of blue, green thru the atmosphere).


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### Answer by username_5 on 2024-01-25. Score: 0

If the Sun was an early K or late G-type star for example, the white that we see in objects such as snow would still exist - just reflecting yellow light instead of what we are used to. If you look outside at snow in the evening, while the sun lower on the horizon and is yellowed due to Rayleigh scattering (or in other words, at about 4500K in color temperature, congruent with orange-yellow stars), the snow would still appear as white, just reflecting a bit of that color now. So no, an object's color is not directly influenced by the Sun's light. That would be like saying a piece of paper turns orange when it's under a warm lamp.

However, if the Sun was yellow, there would be more noticeable effects on our planet. For example, the sky might be a more pale color, as yellow stars do not contain as much blue light as white stars do, meaning the atmosphere has less of it to scatter. With that in mind, the Sun itself would also appear more orangey in our sky. Redder colors in rainbows would be more prominent, while blues would be faded. Then our planet will frost over because we're out of our habitable zone of our now cold star...


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