What happens to the violet? Some of the violet light is absorbed by the upper atmosphere. Also, our eyes are not as sensitive to violet as they are to blue. Closer to the horizon, the sky fades to a lighter blue or white. The sunlight reaching us from the horizon has passed through even more air than the sunlight reaching us from overhead.
The molecules of gas have rescattered the blue light in so many directions so many times that less blue light reaches us. As the Sun gets lower in the sky, its light passes through more of the atmosphere to reach you. Even more of the blue and violet light is scattered, allowing the reds and yellows to pass straight through to your eyes without all that competition from the blues.
Also, larger particles of dust, pollution, and water vapor in the atmosphere reflect and scatter more of the reds and yellows, sometimes making the whole western sky glow red. The Short Answer:. Gases and particles in Earth's atmosphere scatter sunlight in all directions. Blue light is scattered more than other colors because it travels as shorter, smaller waves.
The type of scattering that occurs is known as Rayleigh scattering named after Lord Rayleigh John William Strutt who discovered it. This type of scattering increases as the wavelength of light decreases, so blue light is scattered more than red light by the tiny air molecules in our atmosphere.
At noon, when the Sun is overhead it appears white. Hence the Sun and skies look redder at dawn and dusk.
The low density of air molecules means that the Rayleigh scattering that causes our skies to be blue on Earth has a very small effect on Mars. We might expect it to have a very faint blue coloured sky, but due to the haze of dust that remains suspended in the air the daytime sky on Mars appears more yellow. This is because the larger dust particles absorb the short wavelength blue light, and scatter the remaining colours to give a butterscotch hue over the Martian sky.
When the air is too thin for gas molecules to collide with each other, we call it an 'exosphere' instead. But what makes the sea blue — is it reflecting the blue of the sky?
Water molecules are good at absorbing longer wavelengths of light, so when sunlight hits the water the reds and oranges get absorbed. The shorter wavelength blue light is absorbed very little and much of it is reflected back to our eyes. This article has been written by an astronomer at the Royal Observatory, Greenwich.
Written and illustrated by astronomical experts, Storm Dunlop and Wil Tirion, and approved by the astronomers of Royal Observatory Greenwich Essential cookies always enabled These need to be enabled to ensure the website works properly. Analytics cookies These are used to see how people use our website so we can make adjustments and improvements.
Advertising cookies These are used to make advertisements on our website more relevant to your interests. Skip to content Simple answers to common questions: why is the sky blue? So, why is the sky blue? First ask Baby what she thinks: One way to encourage critical thinking is to prompt Baby to form conclusions on her own, before you offer an explanation. Consider finding an age-appropriate book or online resources, like videos and pictures, about these topics, or similar ones. The KidsKnowIt Network,
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