I've watched hundreds of sunsets in orbit. Like you can see in the picture in message 11, only the atmosphere closest to the planet appears red and when the sun is seen through that atmosphere it appears red.
And here's a picture I took myself
Thanks for posting your actual sunset picture from orbit, how cool is that? This is an interesting example to simulate and here is the result, also showing the red atmosphere only in the very lower layer.
Note the sun in the simulation is hiding somewhere in the atmosphere without camera flare being modeled.