The common perception of the Sun as being yellow, orange, or red can be misleading. In fact, the Sun is essentially an amalgam of colors that, when combined, appear white to the human eye. This white look of the Sun is easier to observe when viewed from above the Earth's atmosphere. Astronauts and high-altitude pilots often witness this phenomenon, noting that the Sun does not possess the yellow or golden hue usually visible at ground level.
This misunderstanding originates from the Earth's atmosphere, which acts as a filter altering the way light is perceived. When sunlight passes through the Earth's atmosphere, molecules and small particles in the air scatter the blue light in different directions. This scattering, known as Rayleigh scattering, is more effective at short wavelength light (blue) than at longer wavelength light (red). Thus, when the Sun is high in the sky, direct sunlight appears less blue and more red and yellow. However, during sunrise and sunset, the Sun's rays pass through a greater thickness of Earth's atmosphere, which scatters blue light so much that the remaining light seen from the surface takes on a reddish hue.
It’s also important to note that the Sun emits radiation across most of the electromagnetic spectrum, although not equally across all wavelengths. The peak of the sun’s spectrum is actually in the visible range, and more towards the green part of the spectrum. However, because our atmosphere scatters green light much less than blue, and because our eyes are more sensitive to certain colors, the Sun’s light is perceived as more of a pale yellow when it reaches the surface of the Earth.
Understanding this concept helps in comprehending more about other astronomical phenomena as well, such as why other stars may appear differently colored due to their temperatures, sizes, and the compositions of their atmospheres. Essentially, the color of a star, including our Sun, can tell scientists a lot about its physical properties and the nature of the light it emits. Thus, while the Sun might sometimes appear yellowish from our viewpoint on Earth, in the vacuum of space, it is indeed a bright white star.
