Hey Sonny! Thanks so much!Just a stellar image Jim, I've never blended two images before. But this gives me motivation to try it.
You really should do it. I would say the majority of us here do that so we can process the ground layer separate from the sky. Well, let me restate that, most of us take a single image, then process the ground separate from the sky and then blend those two back into 1 original shot. Especially at night, the ground layer and sky layer require 2 different white balances to look right. A lot of times the ground layer will need to be lit up more then the sky would be.
We have some blending tutorials in our Article section. If you have questions, please be sure to ask, any of us would be glad to help.