Blue Sky, Red Sunset: Light, Atmosphere & Scattering

This podcast explains why the sky is blue and the physics behind vibrant red and orange sunsets. It details how sunlight passing through Earth's atmosphere undergoes Rayleigh scattering by tiny air molecules (nitrogen, oxygen). Blue light, with its shorter wavelengths, is scattered most effectively, causing the sky to appear blue.

At sunrise and sunset, the Sun's light travels a longer distance through the atmosphere, scattering blue and green light away, which allows red and orange light (longer wavelengths) to reach our eyes, creating the characteristic colors. The overview also discusses the visible spectrum of light, how dust and other particles in the atmosphere can affect sky color, and contrasts Earth's sky with the black sky on the Moon (due to a lack of atmosphere) and the different sky colors observed on Mars.