The combination of a blue sky, dark overhead, lighter near the horizon, along with a reddened Sun at either sunrise or sunset, can all be explained scientifically. Here’s how. Image credit: Robert Villalta / Pexels.

Why the sky is blue, according to science

If you’ve ever wondered where it gets its blue color from, physics has you covered.

“That’s a misconception, Lennie. The sky is everywhere, it begins at your feet.” -Jandy Nelson

One of the first questions a curious child often asks about the natural world is “why is the sky blue?” Yet despite how widespread this question is, there are many misconceptions and incorrect answers bandied about — because it reflects the ocean; because oxygen is a blue-colored gas; because sunlight has a blue tint — while the right answer is often thoroughly overlooked. In truth, the reason the sky is blue is because of three simple factors put together: that sunlight is made out of light of many different wavelengths, that Earth’s atmosphere is made out of molecules that scatter different-wavelength light by different amounts, and the sensitivity of our eyes. Put these three things together, and a blue sky is inevitable. Here’s how it all comes together.

Light of many different wavelengths, not all of which are visible, are emitted by the Sun. The atmosphere affects every unique wavelength differently, resulting in the full suite of optical phenomena we can observe. Image credit: Negative Space / Pexels.

Sunlight is made up of all the different colors of light… and then some! The photosphere of our Sun is so hot, at nearly 6,000 K, that it emits a wide spectrum of light…