Let’s look at the renderings first:
Create a layer and fill in the background color:
Use the brush to embellish the stars, and add dynamic colors to make the stars have different colors:
Start drawing the basic lines of the aurora. Outline path stroke 
The effect after stroke
Duplicate the previous layer, save one, and use radial blur on the other to get the following effect:
Because it’s not obvious, I copied a few more and merged them together:
Color with Hue Saturation:
This is what it looks like after coloring:
