color of a flame

[laral5]

What causes the different colors of flames at different temperatures? If blue/violet is the hottest flame, why is the sun look yellow?

[fantastical]

Because our sun is one of the smallest and least warm stars out there. It being yellow shows us that visually, exactly what you say about the color of flames.

What causes the different colors in flames, dependent on temperature? Well, the temperature is what causes the color to be different.

[mibn2cweus]

The sun radiates a broad spectrum of visible light.  This spectrum actually peaks in the green range.  The sun is bluer than it appears through the earth�s atmosphere because it scatters the blue light, thus the blue sky.  This scattering causes the sun to appear red when it is closer to the horizon.

[steveb]

mibn u have too much time on your hands, lol

[tony1941]

Have a look here: http://en.wikipedia.org/wiki/Color_temperature

This covers, I think, your question as it relates to "black body" radiation.  If you are thinking of, for example, the colour of a gas flame when salt is sprinkled into it (yellow) or copper held in it ( blue/green) then the mechanism is different and is discussed here: http://en.wikipedia.org/wiki/Spectral_lines