Leonardo Da Vinci was the first to explain why the sky is blue.
Italian artist and inventor Leonardo da Vinci is known to be the first person to explain “why the sky is blue”, in his writings compiled around the early 1500s. To explain the phenomenon, he monitored sunlight passing through wood smoke, suggesting how light is scattered.
While he was on the right track, Leonardo wasn’t equipped to understand the essential ingredient, which is a subtle optical phenomenon called scattering. Indeed, it was not until 1871 that the noble English scientist, Lord Rayleigh, got to the bottom of it all. Scattering is something that happens whenever light rays strike microscopic particles – including molecules of air. Thus, the flood of sunlight hitting the atmosphere is simply scattered in all directions, which is why the sky is luminous in daytime.
The reason it is blue, though, is that Rayleigh’s theory predicts that blue light is about 3.2 times more likely to be scattered than red light in any interaction with a particle. And that is exactly what we see. While the light of the sky still contains red light, it is overwhelmed by the blue.