But as the Sun sets, the sky around the Sun begins to take on a blue-gray tone. During the daytime, the Martian sky takes on an orange or reddish color. Photos from NASA’s rovers and landers on Mars have shown us that at sunset there is actually the opposite of what you’d experience on Earth. These fine particles scatter light differently than the gases and particles in Earth’s atmosphere. It all depends on what’s in the atmosphere! For example, Mars has a very thin atmosphere made mostly of carbon dioxide and filled with fine dust particles. The sky appears red because small particles of dust, pollution, or other aerosols also scatter blue light, leaving more purely red and yellow light to go through the atmosphere. Sometimes the whole western sky seems to glow. Even more of the blue light is scattered, allowing the reds and yellows to pass straight through to your eyes. All this scattering mixes the colors together again so we see more white and less blue.Īs the Sun gets lower in the sky, its light is passing through more of the atmosphere to reach you. As the sunlight has passed through all this air, the air molecules have scattered and rescattered the blue light many times in many directions.Īlso, the surface of Earth has reflected and scattered the light. The sunlight reaching us from low in the sky has passed through even more air than the sunlight reaching us from overhead. This is why we see a blue sky most of the time.Ĭloser to the horizon, the sky fades to a lighter blue or white. Blue is scattered more than other colors because it travels as shorter, smaller waves. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Or scatter it (like molecules of the gases in the atmosphere) Blue light waves are shorter than red light waves.Īll light travels in a straight line unless something gets in the way and does one of these things:. Some light travels in short, 'choppy' waves. Like energy passing through the ocean, light energy travels in waves, too. If you visited The Land of the Magic Windows, you learned that the light you see is just one tiny bit of all the kinds of light energy beaming around the universe-and around you! When white light shines through a prism, the light is separated into all its colors. But it is really made up of all the colors of the rainbow. And it took a long time to figure it out! Have you ever wondered why?Ī lot of other smart people have, too. Click here to download this video (1920x1080, 87 MB, video/mp4).

Click above to watch this video about why the sky is blue! Voiceover provided by NASA scientist Dr.

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