Creating a space skybox scene

I am curious on how to go about creating a skybox to look like a space scene. I wnat to recreate a scene similar to these:
Celestial clouds
Celestial cloud 2
Planet backdrop
Planet backdrop 2
Asteroid backdrop
Misty background

I wanted to create a space atmosphere scene to have my game take place in. How would i go about doing this? I know i can use particle emitters for the mist and such, but how would i create the illusion of a vast openness? Im assuming a skybox is needed here for that.

Skybox wraps your scene with a large globe that gives you a universal background. All of the examples you have shown are nice skyboxes. If you create the art to hide the fact that it’s a sphere, it will look like deep space.

Use a tool like this: http://www.diardsoftware.com/ to create your space art. Then get a Skybox template. There are several skybox textures included in Unity’s Standard Assetts: Assetts → Import Package → Skyboxes

Piece the Skyboxes together in Photoshop to create a Skybox Template. This is fairly easy to do as the individual Skybox images are labeled. ( For instance: DawnDusk_back, DawnDusk_down, etc.)

Once you have your uber skybox image, bring in your space art and superimpose it on new layers over the big skybox image. When you’re done, export them and assign them similar names. Now, in Unity, create a new Skybox material and assign the textures to the correct spot in the material.

For more advanced help, see this answer: http://answers.unity3d.com/questions/7881/How-does-one-Create-the-textures-for-a-skybox.html