Discrepancy between Sun's radiated max wavelength and it's apparent color

In summary, Wien's law states that the maximum wavelength radiated by the sun is around 500 nm. However, the sun appears yellow to us, which has a wavelength range of 600-630 nm. This discrepancy can be explained by the fact that we see the sun as white, meaning we observe all the wavelengths of visible light together. This is different from a red-hot poker, where we only observe the lambda max, which is mainly red. This is because the sun's radiation is much stronger than the poker's.
  • #1
ramuramu
5
0

Homework Statement



By Wien's we can determine that the max wavelength radiated by the sun is around 500 nm.
How does this compare to the apparent color of the sun? Attempt to explain this discrepancy.

Homework Equations



lambda_max*T=2.9x10^-3

The Attempt at a Solution



I said that the sun appears yellow to us (600-630nm) even though lambda max is around
500nm (blue-green). This is using 5.79x10^3 K as a surface temp. At first I thought the discrepancy was due to scattering of photons off molecules/electrons but that would yield a higher apparent frequency, not a lower one. Then, I thought it was simply that the sun appears white, we observe all wavelengths together, not just the max one.

Does this make sense?

Although, if you had a red-hot poker you only observe the lamdba max mainly->red. This makes me think there is something more to the answer. We have been studying blackbody radiation in a sophomore modern physics class.

THANK YOU!
 
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  • #2
Your second thought is correct. If you see the sun as yellow at any time when the sun is high overhead, get your eyes checked. We see the sun as white almost all day, so go off of that assumption. The only time the sun appears yellow is when it is close to the horizon.
 
  • #3
Thank you very much. I see. So the simple explanation is that we just observe all the wavelengths of visible light->white. What do you think about the red-hot poker example?
Do you think that the sun's radiation is just so much stronger than the poker's, so that's why with the poker we only really observe the lambda max->red?

THANK YOU, again!
 

What is the discrepancy between the Sun's radiated maximum wavelength and its apparent color?

The Sun's radiated maximum wavelength is in the green portion of the spectrum, while its apparent color is yellow. This means that the Sun appears yellow to our eyes, even though it emits most of its energy in the green portion of the spectrum.

Why is there a difference between the Sun's radiated maximum wavelength and its apparent color?

This is due to a phenomenon called the "atmospheric window." Our atmosphere is transparent to green light, allowing it to reach our eyes and make the Sun appear yellow. However, our atmosphere absorbs most of the green light emitted by the Sun, which is why its radiated maximum wavelength is in the green portion of the spectrum.

How does the Sun's radiated maximum wavelength affect life on Earth?

The Sun's radiated maximum wavelength plays a crucial role in the photosynthesis process for plants. Plants use the Sun's energy to produce food, and green light is the most efficient for this process. Therefore, the Sun's green wavelength is essential for sustaining life on Earth.

Does the discrepancy between the Sun's radiated maximum wavelength and its apparent color have any significance in other areas of science?

Yes, the discrepancy is also relevant in astronomy. By analyzing the light spectrum of stars, scientists can determine their surface temperature. The Sun's discrepancy between its radiated maximum wavelength and its apparent color is an essential factor in determining its surface temperature.

Is there any way to observe the Sun's true color and radiated maximum wavelength?

Yes, specialized instruments such as spectrometers can measure the Sun's radiated maximum wavelength and the overall composition of its light. This allows scientists to observe the Sun's true color, which is a pale white, rather than the yellow we see from Earth.

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