The Sun appears as a yellowish-white color to the naked eye when viewed from Earth. However, during sunrise or sunset, the Sun often appears to be orange or even red. This change in color is primarily due to the scattering of light by the Earth's atmosphere.
When the Sun is higher in the sky, its light has a shorter path to travel through the atmosphere before reaching our eyes. At this point, the atmosphere scatters shorter-wavelength blue and violet light more strongly, which gives the sky its blue color. The remaining light, which is mostly longer-wavelength yellow and red light, continues on a more direct path to reach us, resulting in the Sun appearing yellow or white.
During sunrise or sunset, the Sun is lower on the horizon, and its light has to pass through a larger portion of the Earth's atmosphere. The atmosphere scatters even more of the shorter-wavelength blue and violet light, which results in a greater proportion of longer-wavelength colors, such as orange and red, reaching our eyes. This scattering phenomenon, known as Rayleigh scattering, causes the Sun to appear more orange or red during these times.
Moreover, particles and pollutants in the atmosphere, such as dust, smoke, or pollution, can further scatter and absorb shorter-wavelength light, enhancing the orange or red appearance of the Sun during sunrise or sunset. These particles can also scatter light in a phenomenon called Mie scattering, which can produce vibrant orange and red hues in the sky.
It's important to note that the actual color of the Sun is white, but atmospheric scattering and other factors can make it appear differently when observed from Earth.