The Sun isn't yellow?

Question

I read on an astronomy site that our sun's rays are blue-green (peak wavelength of 500 nm), but we see it as yellow due to Earth's atmosphere. I guess that is like looking though the blue part of 3-D googles. Has anyone heard of this before? Why did I just hear of this? source - http://www.mira.org/fts0/stars/114/txt001w.htm

Answer 1

Earlier, I wrote "your source is incorrect." But I just watched an astronomer make a presentation about this same thing and he agreed that we do see the sun as yellow rather than green in some part due to atmospheric scattering. However, the following explanation, the one I gave before, may also play a part:

The sun's emission peaks in the blue-green area, but it is a yellow-green star because not all of the light it emits is at it's maximum emission wavelength and it's light emission is skewed to higher wavelengths.

The sun is a G2V spectral class star (that means yellow) with surface temperatures around 5780 K.

You can find the wavelength of maximum emission using Wien's Law:

wavelength of maximum emission = 0.0029/T

where T is temperature in Kelvins. I just worked it out on my calculator and got ~501 nanometers, just like your source. This does correspond to a blue green color.

However, this is just the wavelength of maximum emission. In a blackbody curve (see the first source below for a picture) you can see that this curve is skewed to the right meaning that more light is emitted on the right side of the wavelength of maximum emission than on the left side. So the sun is actually yellow green because when you look at all of the light it emits weighted by the black body curve, that's how it comes out. Your source was wrong because it assumed that only the wavelength of maximum emission mattered.

Answer 2

Most of the blues and greens of raw sunlight are scattered by the atmosphere and fade away. The longer wavelengths from the orange on downward towards the reds are less effected. As a result, we see the remaining yellowish and orange hues of the sun more than the other colours.

The blues and greens are scattered approximately 10 times more than the longer wavelengths.

The scattering of the bluish light in all directions is what causes the bluish colour of the sky and the sun colour to appear more yellowish or orange to the eye, depending on local atmospheric conditions.

Also, the peak wavelength does not automatically mean that the light source must appear that particular colour to the eye. It can be overcome by a combination of other colours mixing together and also depends on the biochemistry of the observing eye.

Different creatures may also see the sun as being a very different colour than humans may perceive.


Perhaps this article will help explain it better.

http://en.wikipedia.org/wiki/Stellar_classification

Answer 3

Um all video I have seen of the sun taken from outside our atmosphere it clearly appears yellow so I'm calling your info bogus

Answer 4

what are you talking about? what is your question? when you look at the sun you see its bright yellow, yes, but are you talking about the electromagnetic spectrum? whatever, but from the last part of your question, the light is usually bent like a prism and that color is seperated, hence, the sky is blue.

Answer 5

Hi,

All I know is there is burning fire, huge explosions on the Sun. That makes me think it is more red than yellow.

Karl
http://www.bestlaserhairremoval.info/

Answer 6

sun is not yellow. Of course nobody knows clearly

today it is yellow
tomorrow it may be green

who knows - what our science is going to say

Answer 7

Yep.
The light of moon is yellow.
But we see it white daytime.