Why the Sky is Blue and the Sun is Yellow

It's the same reason! Our atmosphere - blue light is scattered most easily by our atmosphere, and thus it appears blue. The remaining light trends towards the red end of the spectrum, which translates to a yellowish color for the sun. If you were to look at the sun in space, it would appear much whiter.

Additionally, as you can see above, the sun is changing color based on its position in the sky during the day - and the reason sunrises and sunsets are redder than Noon is again, the atmosphere - when rising/setting, the light has to go through more atmosphere than at noon, thus increasing the scattering, making it appear redder.

The more you know....


l.e.s.ter said...

This is a question I've asked many times, especially in early childhood, and I'm still not satisfied with the answers. How does the atmosphere "scatter" light? Is there particulate that bounces the light? Why is blue the "easiest" to scatter? What does a trend toward red translate as yellow? Why does the light go through more atmosphere at low angles? Isn't atmosphere a constant?

Redshirt said...

Good questions! It's a specific function of the wavelengths of light acting with the gases in our atmosphere - 1st point: A different atmosphere would produced a different colored sky.

In our case, the longer the wavelength of light, the easier it passes through these gases without being interfered with. Shorter, higher frequency wavelengths cannot pass as easily - so it's really a physical interaction - photons hitting molecules of gas.

The redder the light, the longer the wavelength - the bluer, the shorter. Thus, the blue light gets stripped out as the photon wave comes into the atmosphere, and the redder light passes through.

Red plus other colors make the yellow of the sun - pure color mixing.

As for sunsets/sunrise, picture the earth and the sun - at noon, the sun is directly above, passing through the least possible amount of atmosphere. At sunrise/sunset, it's at a 90 degree angle, thus, the light has the pass through more atmosphere - physically. Given the extra atmosphere, more photon hit gas molecules, causing redder skies.

Does that answer your questions?

Redshirt said...

And also! The horizon effect (more atmosphere to pass through at sunrise/sunset) is also the reason the sun/moon look bigger when they rise and set as opposed to other times of the day.