why is the sun yellow?

Answer 1

It's due to its composition and temperature. And its temperature is partly due to its mass.

Hotter stars are bluer, while cooler stars are redder. Our sun is right in the middle, a yellow "G" class star.

In 5 billion years, when it has nearly used up all its hydrogen and begun fusing helium, the sun will swell up and get redder. It will be a "red giant." Its surface will be cooler than it is currently. After this stage, it will shrink to be a much smaller star than it currently is, and will take on a white color. This "white dwarf" will be fusing heavier and heavier elements for energy until it reaches the point where it takes more energy to fuse them than is caused by the reaction. At that point, the sun will die, and become a burnt out, black hunk of metal in space, slowly cooling off.....

Answer 2

The sun a white color which, because of atmospheric scattering, appears yellow as seen from the surface of the Earth. This is a subtractive effect, as the preferential scattering of blue photons (causing the sky color) removes enough blue light to leave a residual reddishness that is perceived as yellow. (When low enough in the sky, the Sun appears orange or red, due to this scattering.)

By the way, to respond to a previous answerer: fire is yellow because that is the actual color of the flame produced by the particular chemicals that are burning. Pure flame is generally a bluish color; certain components in the fuel can color the flame different colors. Wood flames are generally yellow or orange, but some fuels burn green and bright blue. This is how fireworks achieve their colors.

Answer 3

Oh,man.You could have asked for a more harder question.



The sun a white color which, because of atmospheric scattering, appears yellow as seen from the surface of the Earth. This is a subtractive effect, as the preferential scattering of blue photons (causing the sky color) removes enough blue light to leave a residual reddishness that is perceived as yellow.

Answer 4

The sun is not yellow.

The peak in the sun's spectrum occurs at a wavelength that activates two different color receptors. Although your brain would interpret that simultaneous activation as 'yellow', the sun emits very nearly as strongly through all visible wavelenths...so it appears white if you view it under clear conditions.

It only appears yellow - or red...or orange - mainly due to selective absorbtion of the shorter wavelengths by particulates in the atmosphere. This is most easily seen as sunset approaches.

Answer 5

Color is just another word for wavelength; light behaves like a wave, and the color of the light depends on the wavelength. Planck worked out a mathematical relation of temperature, color and brightness of a freely glowing object. He found, as Wien did, that an object at a given temperature will emit most of its light at a certain wavelength, and less at all other wavelengths. When you plot up the brightness of an object versus the wavelength (or color), you get a curve now called a "Planck curve", or a "blackbody curve", because it represents a black object heated up.


This is why stars are different colors: they have different temperatures! Vega is a very hot star, and so it glows blue. Betelgeuse is much cooler, and so it looks red. I will point out here that stars are really not blackbodies, and some deviate substantially from being so. They absorb light, taking light from one part of the spectrum and re-radiate it at another. These curves are only approximations. The Sun, for example, should peak at about 5000 Angstroms or so, having a surface temperature of 5500 K. However, due to complicated processes, it actually peaks bluer than that, around 4800 Angstroms (a solar spectrum plot can be found here). Oddly, when you mix all the colors of sunlight, you get white. It may peak in the blue, but the combination of colors (and the way our eye interprets them) makes us perceive this light as white. Many people claim the Sun looks yellow to them. I am not sure why, and have never found an adequate explanation. Is it contrast with the blue sky? I don't know.

So, back to the original question: why do so many stars look white? Are most of them like the Sun?

Nope. Oddly, the vast majority of stars in the sky are cool, red stars, usually too dim to see. The reason most stars appear white to us is because we have two different kind of light sensors in our eyes. Sensors called "rods" detect brightness, while sensors called "cones" detect color. The cones are not very sensitive, so if a light is too dim they are not activated, and we perceive the color as white. So even a red star looks white if it is dim, and only brighter stars look like they have color to us!

Answer 6

Our sun is termed a yellow dwarf, and it has to do with the size. A photon is released during the hydrogen fusion process, and it takes between 100,000 and 500,000 *years* to reach the surface; during that time, the photon has had energy added to it and taken from it, but by the time it reaches the surface & escapes into space, the wavelength we mostly see is in the yellow range.

Answer 7

On a clear day, Rayleigh scattering makes the sky look blue due to scattering preferentially of blue light. Rayleigh scattering is proportional in intensity to the inverse fourth power of the wavelength, therefore shorter wavelengths (blue, violet) are scattered much more than longer ones (red, orange). Especially when the sun is getting close to the horizon, you're seeing its colour minus some of the blue/violet, so it appears red - a little higher orange - a little higher yellow.

Answer 8

Imagine refracting light through a prism onto a white wall. A type of rainbow appears with seven colors. In order from lowest to highest energy, they are: red, orange, yellow, green, white, blue and violet. Stars tend to shine predominantly in one of these color bands. We call this the star's spectral class.

The sun is actually a yellow dwarf, we give it the designation G2V. The "G2" refers to its position of the range of colors. Yellow stars emit more of their radiation in infrared than in ultraviolet, though they are fairly balanced in this regard. The Roman numeral "V" refers to the luminosity class of dwarf stars (except white and brown dwarfs, which is a different matter).

If you move down the spectrum toward red, you find dimmer stars which shine more in infrared and far less in ultraviolet. Move in the opposite direction, and you find stars that give off more light in the UV than IR frequencies.

Each color band is broken down into an index of 0 to 9. The sun is a yellow dwarf that is shifted more toward the green - yellow side of the index. A G8 would be a star shifted more toward yellow - orange. And so on.....

So that's why the sun gives off yellow visible light. Of course, like all stars, the sun gives off radiation across the spectrum from microwave at the red end to x-ray above the blue end.

.

Answer 9

From what I have learned it has to do with the wavelength of the energy given off by the amount of heat it generates. Like there are Red Giants and white dwarfs..and Blue Giants too!

Answer 10

It is not..it appears yellow due to teh heat...to answer ur question: Why is fire yellow??