Question: why is the sky blue?

Fiona Hatch answered on 21 Mar 2012:

Light is made up of different colours, or as scientist call them – wavelengths. You can see these wavelengths when you look at a rainbow.

Our atmosphere is made up of a dense amount of oxygen atoms and these trap the blue wavelengths from the Sun (due to the angle of the Sun as well) and so the blue wavelengths bounce around. This makes our sky/atmosphere look blue.

When the angle changes, like when the Sun sets, the atmosphere also absorbs some red wavelengths and yellow wavelengths, which is why the Sun set looks so red.