What concept explains why the sun appears red at sunset?

• A. Reflection of light
• B. Refraction of light
• C. Rayleigh scattering
• D. Absorption of light

Answer: (C)

The phenomenon that causes the sun to appear red at sunset is primarily due to Rayleigh scattering. As sunlight travels through the Earth's atmosphere, it encounters various particles and gases. During sunset, the sunlight must pass through a thicker layer of the atmosphere compared to when it is overhead during the day. This increased distance means that the shorter wavelengths of light, such as blue and violet, are scattered out more effectively and in most cases, dispersed before reaching the observer's eyes.

What remains predominant in the light spectrum are the longer wavelengths, specifically reds and oranges. This scattering effect allows us to perceive these colors more vividly during sunset, giving the sun its characteristic red appearance. This is a fundamental principle of how light interacts with the atmosphere, illustrating the differences in visibility of varied wavelengths depending on their interaction with particles in the air.