It’s easier to remove power lines by creating a path (using the pen tool) and stroking the path with the healing brush tool than the old way I used to do it. Yay. (I think this technique was added in CS5 or so.)
You can, if you want, combine two different images. One technique I used was to use a darker image over a lighter one and then use the lighten mask. Or vice-versa.
Or, you know, you could pick a sunset one and a thin beam one from here and stack it several layers deep in photoshop (using the above techniques), fuss with it until it looks just so, edit out the stars (for sad and arcane reasons), and then you have this:
And the gradient (bumped up to 100%, but only used at 30%):
Here are two of the originals I used in creating the composited image: