Why Does the Sun Look Red at Sunset?
Why Does the Sun Look Red at Sunset? Sunlight, before it reaches our eyes, must pass through the Earth’s atmosphere. The dust and water particles in the air scatter the sun’s blue and violet rays. When the sun is overhead, its light follows a relatively short path through the air.
Few blue and violet rays are scattered during this short trip, and the sun looks white. At sunset, however, when the sun is near the horizon, we see its rays through a much thicker band of the atmosphere. As a result, more blue and violet rays are filtered out. We see the red and orange rays of light, and the sun looks red to us.
According to Rayleigh’s law, the intensity of scattered light varies inversely as the fourth power of its wavelength. Sunlight consists of seven colors. Of these, red has the maximum wavelength. During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon.
Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red at sunset.