Download the shader on Gumroad for free: https://gumroad.com/l/MwdT
I spent my last 3 days developing a relatively accurate and good looking atmospheric volume based cycles shader. It is universally adaptable to every combination of planet and atmosphere size and i tried to get it as close to reality as possible while still keeping an artistic value to it.
Here is a link to my YouTube Video about it, with download link to the Blendfile: https://www.youtube.com/watch?v=K5GtffIIJR8
As you can see from the photos it is pretty accurate and has a natural coloration in the sunlight with sunsets and everything!
Shader V1 : https://mega.nz/#!6pghCSJT!DQ3nhpc-IT6qceqsSeTvTSVnbIDESM96mVng7O43wY0
Shader V2 : https://mega.nz/#!S9ZHQIxY!O2ckAKYdTwGXz_mVO9ovsiDikkT0_ge7KkFid67HsO0
Shader V3 : https://mega.nz/#!3ogVVaZS!_30RSiVuhE0B1t5Brr4RZzfK-oT9S9I8zDBMKBDZqow