MCQ Detailed View

The sun appears red at sunrise and sunset due to a phenomenon called scattering of light by molecules and dust particles in the Earth's atmosphere. Sunlight is composed of different colors, each with a different wavelength. Blue and violet light have shorter wavelengths and are scattered more strongly by air molecules, while red and orange light have longer wavelengths and are scattered less.

At sunrise and sunset, sunlight has to travel a longer path through the atmosphere to reach our eyes because the sun is near the horizon. During this longer journey, most of the shorter wavelengths (blue and violet) are scattered away from the line of sight. As a result, only the longer wavelengths (red, orange, yellow) survive and reach the observer, making the sun appear red.

At noon, the sun is almost overhead, and sunlight passes through a shorter layer of the atmosphere. Scattering is less intense, and most wavelengths reach our eyes, combining to give the sun its white appearance.

Option 1 (refraction) and option 3 (diffraction) do not primarily cause the color change. Option 2 is incorrect because the sun’s temperature does not change significantly during the day.

Thus, the correct answer is Option 4: Scattering of light due to dust particles and air molecules.