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We now offer the Cool It! card game in our Science Store. Cool It! is the new card game from UCS that teaches kids about the choices we have when it comes to climate change.

Why is the sky blue?

Have you ever asked your parents why the sky is blue? This is probably one of the toughest questions parents are asked, though the answer is pretty simple. The light we have here on Earth comes from the Sun. Sunlight looks white, but is actually a mixt ure of all of the colors of the rainbow. When sunlight strikes air particles (which are very small), the light itself is scattered in all directions, forward, sideways, and backwards.

Air molecules scatter some colors of light better than others. Blue light is scattered the most and red light is scattered the least. In fact, blue light is scattered at least 10 times more than red light. Since the blue rays of lights are scattered th e most, they reach our eyes from all directions and we see more blue than any other color. This makes the sky look blue.

If you were living on Mars, and you asked your Martian parents about the sky there, you'd have to ask the question...why is the sky red? On Mars, dust in the air turns the sky red at midday and purple at sunset!

Submitted by Carlos (Texas, USA)
(July 28,1997)



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Learn about Earth and space science, and have fun while doing it! The games section of our online store includes a climate change card game and the Traveling Nitrogen game!

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF