The reddish appearance of the sun during sun rise and sunset is due to

The correct answer is Option (3) → Due to its. longer wavelength, its scattering is least hence travels longer and reach our eyes

Sunlight is scattered by the air molecules, which are much smaller than the wavelength of light. This Rayleigh scattering varies as

    \( \displaystyle I_{\mathrm{scattered}} \propto \frac{1}{\lambda^{4}} \)

so blue light is scattered much more than red. At sunrise and sunset the sunlight travels a much longer path through the atmosphere; most of the blue and other short wavelengths are scattered out of the beam, and the least scattered red light reaches our eyes.

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Scattering of Light – “… At sunset or sunrise, the sun’s rays have to pass through a larger distance in the atmosphere (Fig. 9.28). Most of the blue and other shorter wavelengths are removed by scattering. The least scattered light reaching our eyes, therefore, the sun looks reddish. This explains the reddish appearance of the sun and full moon near the horizon.”