Sun on a skydome

Trying to create a skydome. Say, I have disabled the default skybox in Unity and want the sky to be represented by a skydome. Now, I want the sun, to have a position on the dome and I want it represented on the dome in a similar fashion that the sun is represented in Unity's skybox itself.

How would I go about doing that? Will I have to write a custom shader for my skydome? And say, if I had two domes, one for the atmospheric colors of the sky, and hiding the stars (blue during the day, orange in the evening, 'transparent' during the night), and another one, showing the 'space' or star dome, where say other planets and stars could be seen.