Why Is the Sky Blue? The Surprising Science Explained Simply
Look up on a clear day and you’ll see it — that perfect, peaceful blue stretching across the sky. But why blue? Why not green, purple, or nothing at all?
The answer lies in the way sunlight interacts with our atmosphere.
Sunlight isn’t just yellow
Sunlight might look white or yellow, but it’s actually made of many colors — all the colors of the rainbow. Each color travels in waves, and blue light has shorter, smaller waves than other colors like red or orange.
The atmosphere scatters blue light more
As sunlight enters Earth’s atmosphere, it bumps into air molecules. Blue light, because of its short waves, is scattered in all directions much more than the other colors. This scattering is called Rayleigh scattering, and it’s why we see blue from every angle.
What about sunsets?
At sunset, the sun is lower in the sky, and the light has to travel through more atmosphere. Most of the blue light gets scattered away, leaving reds and oranges to dominate.
So, the sky is blue thanks to light physics, air molecules, and the way our eyes interpret all that scattering. Nature’s science show — and it’s free every day.