Why Is the Sky Blue?
Sunlight scatters in our atmosphere, painting the sky blue every day.
Deep Dive
Sunlight hitting Earth's atmosphere scatters in all directions. Blue light, with a wavelength closer to the resonant frequency of nitrogen and oxygen molecules, scatters more effectively than other colors. This widespread scattering makes blue photons reach our eyes from every part of the sky, causing the blue appearance. The phenomenon, called Rayleigh scattering, also explains red sunsets and the white color of clouds.
Why It Matters
This fundamental physics explains everyday natural phenomena and the colors of other worlds.