The West Texas sky really looks black at night but it is a deep 3-D black. To reproduce 3-D on a flat surface is just a metaphor so I used the dark blue made from purple+green for the stars background. The middle value blue at the top of this detail is ultramarine+bit of white. The blue at the horizon is the Pthalo+Diox blue + white. A whole dialogue of blues with red & yellow bits in the stars to make an imitation twinkle. I know some is lost in photographic reproduction but this gives the idea.