Why does the sun shine red?

The sun itself remains at a constant color (in the short-term, anyway - it will change color slowly over billions of years) - what you're seeing is how the sunlight is being distorted by Earth's atmosphere, including pollution, dust, clouds, etc. The reason it looks redder near the horizon is that when the sun is near the horizon, it's light is passing through more clouds, dust and pollution before it reaches your eye than when the sun is directly overhead.

Sometimes the sun gets tired. When it is tired, like at night, or when it is first waking up in the morning, the light rays travel more slowly, and as we know, slow light is red. Red is the slowest visible light.

That is why traffic lights have the colors they have. Red is the slowest light and means stop. Yellow is slow, but not as slow, so it means slow down. Green is faster light than the rest, so means go.

Orur sun is just a slow sun.

So if traffic lights had a blue or purple light that means drive way over the speed limit.. since those are faster then green. Interesting, previous poster!

by the way, light color isn't determined by the speed of the light. All light travels the speed of light. What matters is the length of the wave of the electromagnetic radiation.

The sun is always shining the same color (like a yellowish orange), but when the sun's light hits our atmosphere, different elements change what the color of the light looks like to us.