Answer:
Scattering of light is responsible for the red appearance of the sun at sunset and sunshine. Sunlight have seven colors which is denoted by VIBGYOR in which violet is having the least wavelength and red is having the highest wavelength.
During sunshine and sunset, the sun is close to the horizon as a result sunlight has to travel more distance to the atmosphere so most of the colors are scattered in the atmosphere due to their shorter wavelength but red light due to the highest wavelength does not scatter much.
As a result, the only red light of the sun reaches our eyes which generates the red appearance of the sun at sunset and sunshine.
