Make one sphere for your planet texture and make another sphere, slightly larger, with 95% transparency.
Set the Diffuse Render Shader for the transparent sphere to "Planet Glow"
In the Planet Glow options:
- Set "Halo Starts" to something high, like 95%.
- Set "Halo Glow" to something low, like 5%.
Plop the model in a Chor.
In the camera properties, set Render Options > Plugin Shaders to ON.