Explanation

• the sun appears red at sunrise and sunset while it appears white at noon because Of the Scattering of light due to dust particles and air molecules.
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concept:

• It is due to the scattering of light.
• At noon, the sun is at the nearest point to earth.
• Hence all the colors get scattered almost equally and this you see white light. 
• But during sunrise and sunset, the sun is at the longest position.
• Here blue light gets scattered off and due to the larger wavelength of red light, it can travel a longer distance and hence reach our eyes.
• This we see the sun's red