Facts
Real facts about everything, written for your grade.
Sunlight is made of every colour. The air scatters blue light more than the others, so blue comes at you from all over the sky.
Sunlight looks white, but it is really every colour of the rainbow mixed together. You can see them come apart when light goes through a prism.
Light travels in waves, and the colours have different sizes of wave. Blue light has shorter, smaller waves than red light.
When sunlight comes into the air, it bumps into the tiny bits of gas that air is made of, and they bounce it off in every direction. That is called scattering. Blue light gets scattered much more than the other colours, because its waves are short. So blue light comes to your eyes from all over the sky, and the sky looks blue.
When the Sun is low, its light has to travel through much more air to reach you. Most of the blue gets scattered away on the way, and the reds and yellows are what is left to reach your eyes. Dust and smoke in the air can scatter the blue too, which makes some sunsets extra red.
Never look straight at the Sun, even at sunset.
This answer follows NASA Space Place's Why Is the Sky Blue?, read on 6 Nov 2026.
The page explains scattering by gases and particles in the air and why blue is scattered most, and the redder light at sunset, with the same pictures in words a child can follow.
For a hands-on look, the Moon and sky pages have things to watch for outside.
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