<p>The light of the Sun is white because our eyes are evolved to work with it as the primary light source. Other stars look white in the night sky because they are too faint to activate the color receptors in our eyes, but bright enough to activate the brightness receptors.</p>
<p>But how red or blue would other other stars actually be if we could look at them from a distance that results in the same brightness as the Sun on Earth?</p>
<p>I know that starlight is blackbody radiation, which is the same phenomenon as the glow from hot metal or carbon we see on Earth all the time. Small red dwarfs with temperatures of 2000K would be the temperature of molten iron, and as such glow orange-yellow. That's already quite close to white.</p>
<p>Do K-type orange dwarfs look any different to the Sun at an equivalent brightness? Would the dominant wavelength of blue stars be able to overcome the brightness of the red to yellow wavelengths and actually cause blue sunlight?</p>

CC BY-SA 4.0
2021-09-23T14:39:20.967Z
Do you mean absolute magnitude, the magnitude from 10 parsecs distance or apparent magnitude from 1 au?
WarpPrime
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2021-09-23T14:54:20.070Z
Also, stars mostly follow blackbody radiation, so a typical 2000 K red dwarf would have an orangish-red color. There isn't such thing as a yellow star as the orange phases toward whiteish-yellow. Molten iron does not follow the laws of blackbody radiation (in terms of color).
WarpPrime
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2021-09-23T23:52:56.443Z
Colour and magnitude are two independent variables.
AtmosphericPrisonEscape
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2021-09-24T01:12:01.737Z
@uhoh Read the question.
AtmosphericPrisonEscape
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2021-09-24T01:14:27.653Z
@AtmosphericPrisonEscape oh, my morning coffee has not kicked-in yet. Never mind :-)
uhoh
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2021-09-24T14:16:14.760Z
Absolute magnitude is absolute, regardless of distance. When you consider how the brightness goes down with distance, that's apparent magnitude. Which is the whole point of this question.
Yora
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2021-09-25T03:44:22.023Z
> I know that starlight is blackbody radiation Is that actually true? I thought starlight was generated via nuclear fusion, but could be wrong
Guest
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2021-09-25T11:51:54.707Z
@Yora but perception of colour is dependent on flux and therefore distance.
ProfRob
CC BY-SA 4.0
2021-09-26T09:08:24.160Z
Yeah, so what? I specified that the distance is whatever distance you need to be so that the apparent magnitude is about -30.
Yora
<star><light><spectral-type><visible-light>
What color would stars have with an apparent magnitude of ~-30?
Yora
# What color would stars have with an apparent magnitude of ~-30?

(Asked by: username_0 on 2021-09-23)

The light of the Sun is white because our eyes are evolved to work with it as the primary light source. Other stars look white in the night sky because they are too faint to activate the color receptors in our eyes, but bright enough to activate the brightness receptors.

But how red or blue would other other stars actually be if we could look at them from a distance that results in the same brightness as the Sun on Earth?

I know that starlight is blackbody radiation, which is the same phenomenon as the glow from hot metal or carbon we see on Earth all the time. Small red dwarfs with temperatures of 2000K would be the temperature of molten iron, and as such glow orange-yellow. That's already quite close to white.

Do K-type orange dwarfs look any different to the Sun at an equivalent brightness? Would the dominant wavelength of blue stars be able to overcome the brightness of the red to yellow wavelengths and actually cause blue sunlight?

**Tags:** star, light, spectral-type, visible-light
> **Comments:**
> **username_1**: Do you mean absolute magnitude, the magnitude from 10 parsecs distance or apparent magnitude from 1 au?  
> **username_1**: Also, stars mostly follow blackbody radiation, so a typical 2000 K red dwarf would have an orangish-red color. There isn't such thing as a yellow star as the orange phases toward whiteish-yellow. Molten iron does not follow the laws of blackbody radiation (in terms of color).  
> **username_2**: Colour and magnitude are two independent variables.  
> **username_2**: @uhoh Read the question.  
> **username_3**: @AtmosphericPrisonEscape oh, my morning coffee has not kicked-in yet. Never mind :-)  
> **username_0**: Absolute magnitude is absolute, regardless of distance. When you consider how the brightness goes down with distance, that's apparent magnitude. Which is the whole point of this question.  
> **username_4**: > I know that starlight is blackbody radiation Is that actually true? I thought starlight was generated via nuclear fusion, but could be wrong  
> **username_5**: @Yora but perception of colour is dependent on flux and therefore distance.  
> **username_0**: Yeah, so what? I specified that the distance is whatever distance you need to be so that the apparent magnitude is about -30.  

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