the answer files
sky


Why is the sky blue?

What is lightning?

What are the states of matter?

Does hot water freeze faster than cold?

Why does a can of Coke sink while a can of Diet Coke floats?

Why do you close your eyes when you sneeze?

Why do mosquitoes bite me more than my friends?

Why do your feet stink?

How does gravity work?

How fast does the space shuttle move in orbit?

What is escape velocity?

What would happen if you turned on your headlights while moving at the speed of light?

Why is the sky blue?
POSTED 17 SEP 1998. Each "color" of light is a different wavelength of electromagnetic radiation, and sunlight contains every color of the rainbow. Wavelength doesn't just control color, but also other behavior of radiation. Thus short-wavelength X-rays can pass through our bodies much better than longer wavelength visible light.

Similarly, the various wavelengths of visible light interact differently with molecules in the air. When sunlight strikes these molecules, they scatter -- bounce -- blue rays more than red rays. Since the blue portion is scattered until it seems to come from all directions of the sky, the sky looks blue.

red sun Did you know?
When the sun is low on the horizon, its light must pass more air molecules to reach us than when it's higher in the sky. Because more blue light is scattered, the light coming directly from the sun has a higher proportion of red wavelengths. That's why the sun looks so red at dawn and dusk.

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