Why is the sky blue but red during sunset?

High Noon
Why is the sky blue??may seem to be a simple question, but it actually touches some of the deepest aspects of astronomy and skygazing because it deals with light. eeing?something whether it is a table across the room or a galaxy millions of light years away consists of light entering our eyes and the brain taking the light and creating a picture within our brain. So before asking the question hy is the sky blue?? it necessary to know the answer to the question, hat is light??

Light must enter our eyes in order for us to see it
The Sun emits light with different colors
Different colored light has different wavelengths
Sunlight and the Atmosphere
The atmosphere around the Earth is largely made up of two colorless gases: oxygen and nitrogen. Red and blue light reacts very different from each other to oxygen. Because the wavelength of blue light is roughly the size of an atom of oxygen, blue light interacts with the oxygen and is scattered by it, while red light, with its longer wavelength, goes right pass the oxygen atoms. If the Earth had no atmosphere, the sun light would travel directly from the Sun in a straight line towards our eyes and we would see the Sun as a very bright star in sea of blackness. But because the Sun blue light is scattered by the oxygen in the atmosphere, blue light from the Sun enters our eyes from all sorts of different angles and we see the entire sky as blue. The atmosphere scatters violet light even more effectively, but our eyes are more sensitive to blue. Wherever we look towards the sky, some light is bouncing off an oxygen atom and entering our eyes, making the sky appear to be blue.

Sunrise, Sunset
Who hasn enjoyed watching a sunset as the Sun red disk sinks below the horizon. Why does the Sun now appear red? During sunrise and sunset, the Sun light must pass a greater distance through the atmosphere in order to reach our eyes because instead of dropping directly through the atmosphere, it reaches the Earth at an angle. The same scattering effect on the blue light, also takes place, but the blue light is unable to pass through the extra distance and reach our eyes. This leaves only the red light which passes, unhindered through the atmosphere and reaches our eyes in a direct line with little or no scattering. We see the Sun disk red because its blue light has been blocked by the atmosphere. We don see the entire sky red because there is no scattering and the red light reaches us in a direct line.