The sun appears reddish early in the morning due to a phenomenon called Rayleigh scattering. When the sun is at the horizon during sunrise, its light has to travel through a greater distance in the Earth’s atmosphere before reaching the observer. During this extended journey, the shorter wavelengths of light, such as blue and violet, are scattered out by the air molecules, while the longer wavelengths, particularly red, can reach the observer. As a result, the red color becomes more prominent, causing the sun to appear reddish early in the morning.
This phenomenon is not observed by an astronaut on the moon, as there is no atmosphere on the moon to disperse the light, and therefore, the sun would not appear reddish from the moon’s surface.
In summary, the sun appears reddish early in the morning due to Rayleigh scattering, which causes the shorter wavelengths of light to be scattered out as the sun’s light travels through a greater distance in the Earth’s atmosphere, allowing the longer wavelengths, particularly red, to become more prominent.