What Causes the Sky to Turn Pink at Sunset?

The sky turns pink at sunset because the sunlight has to travel through more of the Earth's atmosphere. When the sun is low in the sky, its light travels a longer path through the air, and blue light gets scattered away, leaving behind reds and pinks. It’s like when you shine a flashlight through a cup of water, the colors change depending on how far the light goes.

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Examples

  1. When you shine a flashlight through a glass of water, it looks redder when the light has to travel farther through the water.
  2. On a clear day, the sky is blue because the blue light scatters more than other colors, but at sunset, that blue light gets scattered out of the way.
  3. Imagine a painter using only red and orange paint, that's what the sun looks like as it sets.

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Categories: Science · optics· light· atmosphere · Text is available under the Creative Commons Attribution-ShareAlike License.