Well it is a photograph of a hurricane from nasa but get familiar with painting in details, using different layer modes, and adjustment layers. its honestly tough to explain how i create works because most of the time my technique varies depending on what i want to achieve. I do have some techniques that i use fairly consistently though. My advice would be to find some tutorials here and follow them but continue to just work and experiment and you will get better and find things that work for you. You can see the progression of quality work in many artists gallery including mine. Just practice, its cliche but its the truth haha there is really no shortcut unless your really gifted
I know what you mean. I think I am a talented designer, but I mostly do layout, logos, websites and point-of-sale campaigns. I've needed to create my own backgrounds, but nothing so wonderful as planets and stars! I appreciate that you took some time to try to explain. I will practice!