Why does the Sun look red when it is setting?
A) Red is the Sun's natural color as determined by Wien's law, but it is only when the Sun is close to the horizon that sunlight can pass through the atmosphere unfiltered.
B) When the Sun is close to the horizon, it is traveling away from the observer at great speed, and the Doppler shift makes it look red.
C) Earth's atmosphere scatters longer wavelength light more easily than shorter, so more red light is scattered out of the sunlight and into observers' eyes.
D) Earth's atmosphere scatters shorter wavelength light more easily than longer, so more red light is left to reach observers' eyes.

Question

Quizplus · Accepted Answer

Earth's atmosphere scatters shorter wavelength light (such as blue and violet) more easily than longer wavelengths (such as red). When the Sun is low on the horizon, its light passes through more of the Earth's atmosphere, which scatters away the shorter wavelengths and leaves more of the longer, red wavelengths to reach the observer's eyes, making the Sun appear red.

Why Does the Sun Look Red When It Is Setting