What makes the sky blue?

Stellarium Mobile has a feature that lets you enable or disable the atmosphere. When it is enabled during daytime, we can see that the atmosphere is blue and the sun is shining bright.

But have you ever wondered, why is the sky blue? The answer might be a lot simpler than you thought!

When light coming from the Sun reaches our planet’s atmosphere, it creates an effect called Rayleigh scattering.

You see, sunlight is considered a white light, which is a combination of all colors. A great analogy would be lighting a white flashlight into a prism. As the light passes through the prism, it gets separated into different colors, creating somewhat a rainbow appearance.

The same thing happens with sunlight. Our atmosphere acts like a prism that separates the colors. The bluer spectrum of colors then scatter throughout our atmosphere which makes the sky blue during the day which turns to a little bit reddish during sunrise or sunset.


When you disable the atmosphere in the app, you can observe that the sky turns dark even in the daytime when the Sun is above the horizon. This is because there is no atmosphere that will scatter the sunlight.

Light Pollution

                             Stellarium Mobile Plus in Apple Store Stellarium Mobile Plus in Google Play Store

                    Available on Google Play and the iOS App Store

Did you know you can also adjust light pollution settings on Stellarium Mobile?

Read more: Light Pollution on Stellarium Mobile

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