First, what makes the sky blue?

The color spectrum is ROYGBIV, moving from Red (low frequency) to Violet (high frequency). In the earth's atmosphere, the most common gases are oxygen and nitrogen, and those gases scatter the higher frequency colors. "The amount of multidirectional scattering that occurs is dependent upon t
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he frequency of the light" ( The colors we see in the sky are the ones that are reflected back in the atmosphere, which means the Violet, Blue, and Green colors will be seen in the sky. Since our eyes are more sensitive to the frequency that the color Blue has, that's the way the sky appears to us.

The Red, Orange, and Yellow colors move through the atmosphere without much interference, and they "tend to reach our eyes as we sight directly at the sun during midday...sunlight tends to be most rich with yellow light frequencies" (, which is why the sun has a yellow-orange color to us.

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So then why does the sky change colors when the sun is rising and setting?

As the sun is rising and setting, the light rays have a farther distance to travel to get to us (see image to left), which means the light is running into more interference. The more interference, the more Yellow and Orange colors that will be reflected back in the atmosphere, which is why the sun looks more Red and Orange, becaue the lower frequencies are still passing through to our eyes.

Sunsets are definitely works of art, and we have them because of physics and the frequencies of different colors. Without physics, we wouldn't be able to enjoy beautiful sunrises and sunsets or blue skies or any of the songs that are about them. Without physics, we would be missing out on a lot of art.