Why Is the Sky Blue? Why Are Sunsets Colorful?—Answers Here

September 9, 2013 Updated: June 24, 2015

The color of the sky has a lot to do with how thick the atmosphere is between the sun and a given vantage point.

Google+ hosted an online conference Monday with meteorologists to discuss age-old questions like “Why is the sky blue?” 

Why is the Sky Blue?

Epoch Times Photo

Image of sky via Shutterstock

The color we perceive in the sky has to do with how far the light must travel to reach our eyes, and which colors in the white light get filtered out along the way.

Brad Panovich, Chief Meteorologist at NBC Charlotte, explained that when the distance between the sun and our eyes is the shortest, violet is the color that makes it through the atmosphere best without being scattered.

Technically, the sky is violet, not blue—our eyes compensate and we see it as blue.

Thus, midday, the sky is blue because the sun is overhead and the light has a shorter distance to travel through the atmosphere.

This diagram, shared by Tim Brice of the National Weather Service El Paso, shows what happens when the sun sets. The light coming in from an angle in the evening must travel through more atmosphere to reach our eyes. When this happens, blue and violet are scattered, leaving more red and orange light.

Epoch Times Photo


Why are Sunsets Colorful?

Some factors in the atmosphere can also affect the color of light reaching our eyes. Smoke particles, for example, filter out yellow light, leaving more vibrant red.


Why is a sunset by a lake or another body of water especially beautiful?

Panovich said it isn’t necessarily that the light is affected; it could simply be that a large body of water often means better visibility of the horizon without trees and other obstacles.


Why is the Sky on Mars Red?

Meteorologist Morgan Palmer said people have asked him “Why is the sky on Mars red?”

The answer is that the wind and red soil combined creates a red dust in the atmosphere. He thinks without the dust, the sky would be a deep blue.