Why Is the Sky Blue?
Rayleigh Scattering
Let’s Talk Science!
Mark, what's your favorite color?
Hmm... blue.
Blue, like the sky?
Exactly. But do you know why the sky is blue?
Not really. It just seems normal that the sky is blue. But I bet you know the reason :)
Honestly, I don’t... but I’m really curious. Let’s ask the teacher to explain!
The Teacher Explains
To understand the color of anything in the world, we need to understand what light is. Without light, there would be no color at all!
What Is Light?
Light is made of electromagnetic waves with different wavelengths (and frequencies). To put it simply—light is made of all colors combined. From red, which has the longest wavelength, to violet, which has the shortest.
Think of a rainbow. It shows how white sunlight splits into all the different colors when it passes through water drops in the air. The rainbow goes from red to violet—long wavelengths to short ones.
Light Scattering – Rayleigh Scattering
During the day, sunlight enters Earth’s atmosphere and bumps into tiny air particles—mostly nitrogen and oxygen molecules. These particles scatter light, but they scatter short wavelengths (like blue) much more than long ones (like red). That’s why blue light spreads in all directions—and we see the sky as blue!
What Happens at Sunset?
When the Sun is setting, its light has to pass through more air. Most of the blue light gets scattered away before it reaches our eyes. What’s left are the longer wavelengths—red and orange—so the sky turns warm and colorful during sunset.