In the early morning the sun appears to be a red color.
The reason that the sun is more a red color in the early morning is because of light passing through the atmosphere.
When the light passes through the earths atmosphere the light with the smaller wavelength which is blue gets scattered from the dust particles that are in the atmosphere and only the red light reaches the human eye lens.
So the sun appears to be red in color in the early morning.
However the sun never actually changes colors but it only appears to be red or different colors during certain times of day when the light passes through.