Question: Why is the Sun yellow?

James Pope answered on 29 Jun 2012:

Hi abichohan,

The sun emits all forms of electomagnetic radiation, of which visible light is the one we can see and is included. The sun also emits infra-red radiation which warms our planet and ultra-violet radiation which causes sunburn and can be quite bad for you if you get to much exposure to it (causing skin cancer) but the ozone layer protects us from it as well as visible light, which is the radiaition we can see.

As for the sun being seen as yellow, it is also seen as being red and orange depending on the time of day and where it is in the sky. The colour changes as the visible light from the sun hits the atmosphere at different angles compared to our position and this determines what colour of light we see, as light from the sun hitting the atmosphere is refracted (bends) and splits from white into the range of colours we see as the different colours bend at different speeds, which when light passes through a raindrop to form a rainbow or through a prism for the same effect.

When the sun is high in the sky, the light is white as there is no bending of the light, so we see it as a white light. The sun as it moves from mid-day towards sunset, changes it’s angle relative to us (gets lower in the sky) and so the light is bent more and more so we move from white to yellow to orange to red coloured suns, red coming right as it sets. A reverse process (from red and oranges to yellows and whites) happens from sunrise towards mid-day!

An interesting fact about this, is that when you see the sun right on the horizon just about to set, but infact the sun has already set, and it’s this bending of the light that causes it to look like it hasn’t!