Ah, the Great Green Globe is coming; better watch out!
Welcome to DPC. I see this is just your 2nd Challenge entry, and I suppose the good news is that you can only go "up" from here! I like your imagination and original thought; the technicals will improve with time and practice.
Yes, your green orb could be a bit more in focus. You might try bracketing your shots. You started with 2.8, if your camera supports it (and I think it does) try some of the other f numbers, 4, 4.5, 5.6...Also set your ISO number yourself. Try it at 100, 200, etc. See what the result looks like. You'll soon have some yardsticks to use for closeup settings.
Again, on long exposures, if you don't yet have a tripod, set your camera on something sturdy, like a book or stack of books, rather than hand-hold it.
You probably know all this. If so, this is just a handy review.
I'm pleased to note that you received a comment from one of our best photographers: e301. If you have the time, you might take the opportunity to study his portfolio and comments to other people as well. He's a great teacher.
I wish you well in your adventures at DPC. And will look forward to seeing more of your work.
You see, I can understand the direction, but I can't see this as high-contrast photography. Sure, there's a big black background, but the tonal range of your actual subject is very limited indeed, is it not? You've also gained white line in your editing (I presume), and only used 1/3 of the availble file size, and two-thirds of the available width. the images here are small enough already. there's a tutorial about re-sizing images for the challenges ... might I suggest that to you, with all respect?