Sunset's Red Carpet

At sunset, sunlight passes through a much thicker slice of atmosphere — far more air than at noon. The extra distance scatters away almost all blue light before it reaches your eyes.

This is why sunsets paint the sky in warm colors. The blue light has already scattered away, leaving reds and oranges to reach your eyes directly. Volcanic eruptions add extra particles that scatter even more blue, producing the most vivid sunsets for months afterward.